Science

Through Glowing Eyes: What Do Cats See?

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Meredith Hemphill

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Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

Joon has a strange habit. Well, a lot of strange habits, actually, but I’m thinking of one in particular. She will stare up at the ceiling at night and yowl. At first, I thought she was hearing our upstairs neighbors. Then I remembered that we lived on the top floor. Is my cat insane, or are there demons in the walls? There’s no way to know. I now live in a detached, single-family home, and she still does the same thing. I’ve never known any other cat to do that, but cats are infamous for looking off into space intently and kind of spookily. Obviously, cats and humans see the world very differently. If you have ever wondered what on Earth your cat is looking at, or just how the world appears to them, then you have come to the right place.

Eyeball diagram
Image from Cat-World.com

Let’s start with the basics: eyeballs. The fundamental structure of the cat eye is pretty similar to that of a human, but there are some important differences that affect how they perceive what’s in front of them. If you haven’t taken an anatomy class since high school and need a refresher on what the parts of the eye in the diagram at left do, the National Eye Institute has a short video that goes over the highlights.

Although it doesn’t so much affect the way they see, while we’re on the subject of eyes it bears mentioning that cats, like many other mammals, have a nictitating membrane inside of their eyelids. This membrane, often called the “third eyelid,” is a semi-transparent, whitish color, and cats close it when they need to protect their eyes from scratches, like if they’re squeezing through a bush [1]. The nictitating membrane should not be visible normally; this could be a sign of inflammation or disease and is a reason to visit the vet [1, 2].

As with most things about the cat body, their eyes are exquisitely adapted to the life of a crepuscular hunter. “Crepuscular” means most active at dawn and dusk, when they are able to maximize the proportion of prey animals they have access to. Both cats and humans have forward-facing eyes, but the position of cat eyes gives them a somewhat wider field of view, about 200 degrees to our 180 degrees [3-5]. Cats also have much larger eyes than humans relative to the size of their heads, allowing them to take in more light in the dimmer hours of the early morning and late evening [2].

Another feature that helps cats see in dim light is a layer of reflective cells behind their retinas called the tapetum lucidum, which is Latin for bright/shining carpet. The tapetum lucidum is common in nocturnal and crepuscular mammals. The mirror-like cells reflect light that has gone through the retina back for a second pass. When you take a picture of your cat with the flash or open the door to find them in a dark room and see their eyes seeming to glow like some kind of hellspawn, that’s just their tapetum lucidum reflecting light at you.

Green cat eyes
Elliptical pupils mean more control over light – Image by Christel SAGNIEZ from Pixabay

There is research to suggest that the slit, vertical pupils of cats are also an adaptation to a crepuscular habit. It allows their pupils to change in size drastically for greater control over the amount of light that reaches their retinas [6]. The change in pupil area between the constricted and dilated states is estimated to be 135- to 300-fold, while human pupils can only change in size about 15-fold [6]. Think about how much the amount of sunlight can change around dawn and dusk, versus during the daylight hours when humans are meant to be most active. The ability to significantly adjust the amount of light let into the eye has likely served cats well.

All this means that cats can see much, much better than we can in low light. However, everything in biology involves trade-offs. For one, cats are rather near-sighted. They can only see clearly up to about 20 ft (6 m) away, while humans can resolve details at 100-200 ft (30-60 m) [3-5]. Cats have also prioritized one type of retinal cell, or photoreceptor, over another.

Cone cells help see details and colors. Rod cells are excellent at absorbing dim light and catching quick movements. Humans have lots of cones, including three types that specialize in picking up the colors red, green, and blue. Cats have lots of rods instead, six to eight times as many as humans [1, 4]. This assists in seeing in low light and in picking up the small, rapid movements of prey [3].

This heightened awareness of tiny movements may also explain the way cats seem to look at nothing. They may just have noticed something too small to register with you. Or your house is haunted. Who knows? Although the abundance of rod cells has great advantages for cats, it causes them to have less visual acuity and poorer color vision than humans. Obviously, they have done quite well for themselves even so. After all, did you see that ghost zip through your kitchen? I don’t think so.

There remains some debate as to the color vision of cats. They definitely see some color. According to some scientists, they may see the world in shades of blue, gray, and yellow [4]. A 2014 study found that cats may actually be able to see some colors in the ultraviolet spectrum, so while they can’t see all the colors we can, it’s possible that they can see colors we can’t [7]. This is because the lenses of their eyes don’t remove all the ultraviolet rays before light reaches their retina, unlike ours, which absorb UV [7]. The study found that the lenses of cats allowed 58.9% of UVA radiation through [7]. Whether there is an evolutionary advantage to this remains unknown.

Brown tabby cat face
The feline cornea allows UVA rays through – Photo from Pixabay at Pexels

Perhaps the greatest question of all is, how do our cats see us? A lot of research has been conducted to assess whether animals recognize faces, and a wide variety of species, including wasps and fish, have been demonstrated to recognize the faces of their own species. Recognizing the faces of other species is a much more difficult task, however. I personally couldn’t recognize the face of a wasp, in all fairness, although I do know just about every stripe and speck on my Joon-bug. Then again, it helps that she’s got so many of those. Well, it turns out that to cats, all human people look alike. Fair enough, honestly.

Lomber and Cornwell trained dogs and cats to choose one of two images presented for a treat, regardless of which image they chose [8]. The image pairs were 1) their handler and an unfamiliar human face, 2) an animal they lived with and an unfamiliar animal’s face, 3) a natural scene they’d learned before and a new one, or 4) two unfamiliar natural scenes [8]. Dogs and cats both showed a strong preference for the face of a familiar animal and a familiar natural scene, choosing that which they knew at least 85% of the time [8]. Dogs kept up the preference for the face of their handler, but cats only chose the familiar human face 54.5% of the time, equivalent to a coin flip [8].

Cats are certainly capable of recognizing their people, but they evidently do not recognize our faces, although they can recognize each other’s faces. As animals that are just barely domesticated, and only because they chose to be, perhaps this should be no surprise. What need would a cat have to recognize human faces in its wild state? Cats have met us a lot farther over than the middle. It’s the least we can do to try and see things their way.

If you want to actually see what the world would look like through a cat’s eyes, artist Nickolay Lamm took simple photographs and then manipulated them to appear as they would to a cat, then juxtaposed the two images [3]. You can see the results of the project in the Wired article linked below.

Works Cited

  1. Gelatt, K.N. (2018, August). Eye structure and function in cats. Merck Vet Manual. https://www.merckvetmanual.com/cat-owners/eye-disorders-of-cats/eye-structure-and-function-in-cats
  2. Farricelli, A. (2019, August 12). The anatomy of a cat’s eye. PetHelpful. https://pethelpful.com/cats/The-Anatomy-of-a-Cats-Eye
  3. Drake, N. (2013, October 16). This is how cats see the world. Wired. https://www.wired.com/2013/10/cats-eye-view/
  4. Thrive. (2019, April 12). Can cat’s see color? https://resources.thrivevet.com/can-cats-see-color/
  5. Ghose, T. (2013, October 16). Feline vision: How cats see the world. Live Science. https://www.livescience.com/40459-what-do-cats-see.html
  6. Calderone, J. (2018, June 30). Here’s why cats have such strange, haunting eyes, explained by science. Science Alert. https://www.sciencealert.com/here-s-why-cats-have-such-weird-eyes
  7. Douglas, R.H. and Jeffery, G. (2014). The spectral transmission of ocular media suggests ultraviolet sensitivity is widespread among mammals. Proceedings of the Royal Society B, 281(1780). https://doi.org/10.1098/rspb.2013.2995
  8. Lomber, S.G. and Cornwell P. (2005). Dogs, but not cats, can readily recognize the face of their handler. Journal of Vision, 5(8), 49, 49a. https://doi.org/10.1167/5.8.49

Published September 6th, 2020

Updated September 30th, 2023

Breed Profiles

Cornish Rex: Curly Cats Fit for a King

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Meredith Hemphill

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Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

White and gray cat on blanket
Image by duodenum82 from Pixabay

Cornwall, England is said to be the birthplace of King Arthur, but it was also the birthplace of a truly unique breed of cat. The Cornish Rex was the first of the rexes, a group of cat breeds with an unusual curly or wavy coat. This foundational breed was named for its place of origin and its resemblance to Astrex or Rex rabbits, which have a similar coat. “Rex” is Latin for king. Fitting, then, that a legendary king and a kingly cat call the same place home.

History

On July 21st, 1950, a calico barn cat named Selena gave birth to a litter of five kittens. Selena’s owner, Nina Ennismore, noticed something unusual about one of the kittens. The bat-eared, cream tom had a soft, curly coat unlike anything Ennismore had ever seen before in a cat, but as a former rabbit fancier, she had seen something similar and recognized the potential. She named the unusual kitten Kallibunker and got in touch with British geneticist A. C. Jude to ask for advice. Jude suggested mating Kallibunker to Selena (known as a backcross in genetic parlance). The first litter produced one kitten with a normal coat and two with curly coats like Kallibunker.

Breeding the newly-minted Cornish Rexes with Siamese, Burmese, and British Shorthairs to widen the gene pool always resulted in cats with normal coats. It was realized that the curly-coat trait is recessive. Kittens must inherit it from both parents. A 2013 study determined that the Cornish Rex mutation is a small deletion in the lysophosphatidic acid receptor 6 (LPAR6) gene, which is important for normal hair shaft development in mammals, including humans (1). Mutations in this gene in humans cause woolly hair syndromes or hypotrichosis (short or sparse hair) (1).

Brown rabbit sitting
Rex rabbit – Image by Vicky Prince from Pixabay

A pair of Cornish Rexes from Kallibunker’s family line were exported to the United States in 1957, where Russian Blues, Havana Browns, and American Shorthairs contributed to the breed as well. The journey to the States was fortunate for the breed’s longevity, as it nearly went extinct in the United Kingdom around the same time (2, 3). The Cornish Rex has made a comeback, however, and was the sixth most popular breed in the Cat Fanciers’ Association in 2019.

Breed Characteristics

Of course, the hallmark of the Cornish Rex is that unique coat. Most cats have three types/layers of hair. On the outside are tough, protective “guard hairs,” about 2 inches or 5 centimetres long on shorthairs and 4+ inches or 10+ centimetres on longhairs (4). In the middle is the “awn hair,” and then the “down hair” or undercoat made of very fine, soft hairs about 0.4 inches or 1 centimetre long (4). Cornish Rexes only have an undercoat, and what fur they do have is wavy or curly. Even their whiskers are curly! The texture of a their coat is sometimes compared to crushed velvet, silk, or, ironically, rabbit fur. Because of the diverse background of the breed, the coat can come in any color or pattern.

The shape of a Cornish Rex is an unique as their coat. They have a slender, arched body with long, delicate legs and small paws. Their waists are small but their thighs are muscular. In fact, despite their dainty appearance, they are generally quite muscular, athletic cats. They only look fragile. They are actually a medium-sized cat, weighing about eight pounds. The tail is long, thin, and tapering. The head is perhaps the most outstanding feature. It is egg-shaped with large, oval eyes, high cheekbones, and a Roman nose. The ears are gigantic and high on the head.

If you find those over-sized ears a little comical, it’s okay to laugh, because Cornish Rexes are known for their sense of humor and love of attention. They are very active, playful, and social cats who always want to be involved in what their people are doing. Cornish Rexes like to snuggle, but not for too long, as these cats are energetic and not usually interested in spending a lot of time laying in your lap. They typically get along with children and other pets. In fact, due to their friendliness and willingness to be handled, Cornish Rexes make good therapy cats (5, 6, 7). They do not do well being left alone for long periods of time, however. They are highly social. Since most of us aren’t home all day, it’s a good idea to have an animal friend if you want a Cornish Rex.

As with any breed, a Cornish Rex is not for everyone. Some people may find their desire to be up close and personal all the time irritating rather than charming. They might be too high-energy for some households. Cornish Rexes can be talkers, probably due to their Siamese ancestry. They are not as loud or as chatty as a Siamese, but they are known to like to hold a conversation once in a while, so if a quiet cat is your preference, then a Cornish Rex might not be a good choice. However, they are great cats for chaotic households (lots of kids, other animals, clients in and out, etc.). They also travel well, so if you want a cat that can go with you on your globetrotting lifestyle, this breed can be a great option.

Health and Care

Despite the early inbreeding, the Cornish Rex has benefited from outcrosses with many breeds. They are a fairly healthy breed with few genetic health risks. There is a somewhat elevated risk in their gene pool of hypertrophic cardiomyopathy, a common form of heart disease in cats. They are sometimes prone to patellar luxation, a condition where the kneecap moves out of place. This may be reparable. Cornish Rex sometimes have hypotrichosis, possibly resulting in bald spots. Bald spots may also be the result of over-grooming because of stress or anxiety, so check with a veterinarian.

Sometimes Cornish Rexes develop skin problems since they lack most of their protective fur. They are particularly prone to sunburn, especially if they have light or white fur. But they are also more likely to feel cold, so if you choose a Cornish Rex, be careful not to let it spend too much time basking in the sun. It may be necessary to apply cat-safe sunscreen, especially if you want to walk your cat or let them into your yard or onto a catio.

Cornish Rex can be sensitive to certain anesthetics and may experiences dangerous side effects (4). If you have one that needs a procedure, be sure to discuss this with your veterinarian.

When it comes to grooming, less may be more. Brushing a Cornish Rex may damage their delicate fur. However, they may have a buildup of oils because they have less fur to absorb them. Depending upon the cat, they may only need a little cleaning around the face and paws, or they may need regular baths. Watch inside the ears and on the claws for oily buildup as well.

Calico cat with curly fur
Photo by Nickolas Titkov from Wikimedia Commons

There is a myth that Cornish Rex are hypoallergenic because they have less hair than most cats. This is not true. Cat allergies are caused by proteins in cat danger and saliva, not by the hair itself. The hair can cause the offending dander to travel farther, and Cornish Rex do shed less, so some people with cat allergies might have less of a reaction to Cornish Rexes than other cats, but there is no guarantee. Rather than get a cat and find out it doesn’t help the allergies, and now you need to re-home it, it is best for someone with cat allergies to hand a cat of a breed they think might be less allergenic first and test their hypothesis.

If you think a Cornish Rex is the cat for you, adopt, don’t shop. Even purebred cats are surrendered every day. Check with your local shelter or see if there is a breed-specific rescue group in your area.

Fun Facts

  • The term “Rex” was first applied to curly fur at a rabbit show where King Albert I of Belgium (1875-1934) entered his curly-haired rabbits. The officials knew they didn’t meet the standards, but they dared not reject the king’s rabbits, so they accepted them but wrote “Rex” for “King” on the score sheets (4, 8).
  • Life magazine ran an article about Kallibunker in 1956. Quite the step up for a son-of-a-barn cat (3).
  • The same mutation that causes the Cornish Rex’s special coat is also found in the rare, lesser-known German Rex, but not in other Rex cat breeds (1).
  • Cornish Rexes have very dexterous paws. They pick up toys and throw them up in the air for their own entertainment. They’re happy to play catch with others, too.

Works Cited

  1. Gandolfi, B., et al. (2013). To the root of the curl: A signature of a recent selective sweep identifies a mutation that defines the Cornish Rex cat breed. PLoS One 8(6), e67105. https://doi.org/10.1371/journal.pone.0067105
  2. Puisis, E. (2019, July 25). Cornish Rex: Cat breed profile. The Spruce Pets. https://www.thesprucepets.com/learn-all-about-the-cornish-rex-cat-4694497
  3. Cat Fanciers’ Association. (n.d.). The Cornish Rex. https://cfa.org/cornish-rex/cornish-rex-article/
  4. Europetnet. (n.d.). Cornish Rex. https://www.europetnet.com/pet-resources/cat-breeds/item/1920-cornish-rex.html
  5. VetStreet. (n.d.). Cornish Rex. http://www.vetstreet.com/cats/cornish-rex#overview
  6. CatTime. (n.d.). Cornish Rex. https://cattime.com/cat-breeds/cornish-rex-cats#/slide/1
  7. Kelley, J. A. (2015, February 3). Get to know the Cornish Rex: A pack of personality in a ballet dancer’s body. Catster. https://www.catster.com/lifestyle/cat-breeds-cornish-rex-personality-ballet-dancer-body-pictures-photos
  8. Houle, T. (2014, December 16). The Cornish Rex. Pet Health Network. http://www.pethealthnetwork.com/cat-health/cat-breeds/cornish-rex
  9. Petfinder. (n.d.). Cornish Rex. https://www.petfinder.com/cat-breeds/cornish-rex/
  10. Cat Fanciers’ Association. (n.d.). About the Cornish Rex. https://cfa.org/cornish-rex/

Published August 30th, 2020

Updated October 15th, 2020

Cat Care

In Search of the Best Cat Food, Part V: Do Indoor Cats Need Indoor Food?

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Meredith Hemphill

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Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

At last, we have come to the final installment of our series on cat food. There remain many questions, I admit, but I am only one person, and there are so, so many kinds of cat food. So I have tried to cover the basics to the best of my ability, and I hope you have learned as much as I have. Today we bring this journey to a close with a question that has haunted me for a long time. Is indoor cat food better for indoor cats?

Image by Crepessuzette from Pixabay

I had always assumed it must be. Why would they make food just for indoor cats (and dogs) if they’re nutritional needs weren’t somehow different? When I became a proper adult and had to buy food for my own kitten, I realized it was actually kind of difficult to find indoor kitten food, and I started to wonder if it might just be a marketing gimmick. But a couple years prior, when I’d bought my hedgehog, I was told I should feed her either hedgehog food or indoor cat food, and indoor cat food only. I was receiving conflicting signals, and I never really got a clear answer. Now the confusion shall end.

The simple answer to the question of whether indoor cats need indoor food is: it depends on the cat. Isn’t that so often the case? The lives of indoor and outdoor cats differ in many ways, but individual cats can be at least as different from each other in either environment, so you have to get to know your cat and possibly ask your veterinarian whether an indoor diet is appropriate, and I’ll explain why momentarily. First, let’s look at what exactly an indoor cat food is.

The formulations vary by company, as is to be expected, but the one thing all indoor diets have in common is a lower calorie content than other cat food. Indoor cats simply do not have the space to roam that outdoor or semi-outdoor cats do, so indoor cats are generally less active and may become overweight. Most indoor diets are also high in fiber. This contributes to the lower calorie count and helps prevent hairballs (1). Indoor cats spend more time grooming than outdoor cats. They may also shed more, being in an environment of consistent light and temperature that confuses their normal shedding cycles (1). Therefore, more hairballs.

Cats tend to be a lot more acrobatic outdoors – Image by rihaij from Pixabay

Some indoor diets may also claim to improve stool quality and/or smell (1, 2). Hill’s Science Diet lists immune-supporting antioxidants and high levels of the fat-burning amino acid carnitine as features of their indoor diet, in addition to low calories and high fiber (3). It is generally agreed that the basic nutritional requirements of indoor and outdoor cats are no different (1, 4). That being said, some indoor cats certainly do have problems with gaining too much weight or coughing up too many hairballs. These cats may benefit from an indoor diet. Changes in weight and lots of hairballs can both be indicative of medical problems, so be sure to check with your veterinarian that there isn’t something more serious going on.

There are some drawbacks to an indoor diet, of course. In in order to decrease calories and increase fiber, the protein content may have to be sacrificed (4). Make sure to carefully examine the protein content so that you know if your cat will be getting enough. Because of the way pet food labels are written, you may have to do some math. See part one of this series for a cat’s protein requirements. Some cats may also benefit more from a diet that is low calorie only or hairball-preventative only. As in, why restrict calories any more than you have to if your cat just needs help with their hairballs? Moreover, many “light” or “low-calorie” cat foods are essentially the same as an indoor diet (1), so keep that in mind when trying to decide what the best option for an overweight kitty is.

To bring things full circle, some indoor cats are likely to benefit from an indoor diet. My first cats, Milo and Cara, absolutely did. Both were very lazy kitties, and it was a struggle to keep their weight under control for much of their lives. Milo was a shorthair, but he shed like crazy, and Cara had long, luscious hair. Both had hairballs, especially Cara. They were fed indoor food most of their lives to help those problems. While Milo was still a pretty fat cat, it did seem to make a difference. I fed Joon an indoor diet for a while because I thought I had to, but I have since stopped. There is nothing inactive about that cat, and her short, fine hair has never given her a hairball in her life. Each cat is different.

Indoor cats can be couch potatoes – Image by photosforyou from Pixabay

I suppose that’s really what this series comes down to. Each cat is different, and each owner has to make the best decisions they can for their cat or cats. There are some things that are true for all cats. They are obligate carnivores. There are certain key nutrients that have to be included in their diets which omnivorous animals like us don’t need. They need to get enough water from their food to be sufficiently hydrated. But every kitty is an individual, and their needs change throughout their life, too. Just like us. The approach to pet food has been pretty one-size-fits-all for a long time. The baffling variety of options today hopefully reflects a shift toward a more flexible, individual approach. It’s our responsibility as pet parents to make sure we look past the marketing to find the best cat food we can for our furry friends.

Post Script: In case anyone was wondering, I still don’t know why hedgehogs must have indoor cat food. If you would like to enlighten me, I am all ears.

Works Cited

  1. Loria, K. (2018, January 22). What’s the difference between indoor cat food and regular cat food? Pet Central, Chewy. https://petcentral.chewy.com/whats-the-difference-between-indoor-cat-food-and-regular-cat-food/
  2. Purina. (n.d.). Feeding your indoor cat. https://www.purina.co.uk/cats/health-and-nutrition/daily-feeding-guide/feeding-your-indoor-cat
  3. Hill’s Pet. (2019, October 30). Nutritional needs of an indoor cat. https://www.hillspet.com/cat-care/nutrition-feeding/best-cat-food-for-indoor-cats-nutritional-needs
  4. Nielsen, M. (2020, May 15). Indoor cat food vs regular food: Why and what to choose. Feline Living. https://www.felineliving.net/indoor-cat-food-vs-regular/#
  5. Country Veterinary Clinic. (n.d.). Best food for indoor cats. Country Veterinary Clinic Blog. https://www.countryvet.net/post/best-food-for-indoor-cats.html

Published August 23rd, 2020

Updated October 15th, 2020

Culture

Why do we say “It’s raining cats and dogs”?

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Meredith Hemphill

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Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

Rain of fish
Pluie de poissons (Rain of Fish) by Olaus Magnus, 1555 – Public Domain from Wikipedia

It’s a dark and stormy weekend, so I felt inspired to investigate the origins of a strange English-language idiom: It’s raining cats and dogs. Cats feature in quite a few English idioms, and all of the ones that spring to mind are really rather strange. This is probably a topic I’ll come back to because I find it fascinating. For anyone who isn’t familiar with the phrase, to say it’s raining cats and dogs means it is absolutely pouring down rain.

But what does this have to do with our pets? Certainly nothing obvious. There have been real life reports of fish, frogs, and other small animals falling from the sky during storms. Seriously, Google it. It’s fascinating. But as far as I know, no one has ever seen cats and/or dogs raining from the heavens. So why would we say it’s raining cats and dogs instead of fish and frogs?

The first known instance of “raining cats and dogs” was in 1738 in Jonathan Swift’s A Complete Collection of Polite and Ingenious Conversation, where he wrote “I know Sir John will go, though he was sure it would rain cats and dogs” (1, 2, 3). However, it may have been in common use before that, and there are literary instances of the phrase in other forms at least as early as the 17th century (1, 2, 3).

As is often the case with language, trying to track down the origin of this phrase has proved tricky. The older and more widely-disseminated an idiom becomes, the murkier its background tends to get. Language naturally changes over time, and the original turn of phrase is often lost. There are several theories that “raining cats and dogs” is what’s known as a corruption of a foreign phrase. That is to say, a phrase in one language is repeated verbatim by native speakers of another, and it evolves into something else.

Waterfall
Image by Sven Lachmann from Pixabay

One of these theories claims that our modern idiom began with the Greek phrase kata doksa, which means “contrary to expectation” (1). It is sometimes used to describe heavy rain, along with other unexpected things (1). This phrase does bear an audiological resemblance to “cats and dogs,” and the use to describe rain in its native language is promising. However, this requires kata doksa to have made its way into English usage. If this happened, no one has been able to track that journey (1).

The Greek word for the thunderous cataracts of the Nile river, Katadoupoi, has also been suggested as a possible source (1). In this case, an obscure French word for waterfall, catadoupe, is said to be the link between the Greek and the English (2, 3, 4). English speakers are thought to have turned the French word into “cats and dogs” over time (4), although some think it rather a stretch to find dogs anywhere in catadoupe (1, 3).

With some reverse-engineering, Italian and Dutch phrases have also been put forth as possible origins, but without solid evidence (1). Another popular theory discards linguistic evolution in favor of Nordic mythology. This school of thought posits that dogs/wolves were associated with Odin, god of storms, thus the canines were themselves associated with stormy winds (1, 2, 3, 4). Cats, then were said to symbolize rain or be thought to bring rain (1, 2, 3, 4). This was either the superstition of sailors (4) or because cats were associated with witches, who rode the storms in the form of their feline familiars (1, 3).

As interesting as that is, the mythology doesn’t support it. Odin is not a storm god (1). Perhaps someone was thinking of Thor? Moreover, the animals associated with Odin are a horse and two ravens, not dogs and wolves (1). While cats and witchcraft became strongly linked in European folklore, they aren’t a part of Nordic myth like this popular theory would have us believe (1).

Maybe the origins of this bizarre idiom aren’t to be found abroad, but rather in England, its native soil. A rather practical but very depressing theory is based on the poor urban infrastructure of 17th century England. The rivers and even the streets were essentially both open sewers and landfills. When animals died, people threw them in the waterways or left them out on the street. Stray and feral cats and dogs were everywhere, too. They were left where they died. Without storm drains, it’s possible that some animals drowned during heavy downpours, contributing to the number of dead cats and dogs that would be seen floating in the streets and rivers during or after a heavy rain (1, 3, 4).

This sad scene may have prompted some people to think that the animals had actually fallen with the rain or at least to make an association between the two phenomena (1, 4). However, people would be used to seeing dead animals on the streets and in their waterways during dry weather as well, so this idea is a bit of a stretch (3). Still, the 1600s were a strange time, and people came up with a lot of strange ideas.

Wet white and black cat on street
Image by Dimitris Vetsikas from Pixabay

Another suggestion, which I remember hearing somewhere, refers to conditions in even earlier times. It starts with thatched roofs. A thatched roof is made of layers of dried vegetation, forming an insulating and waterproof covering. This was the traditional form of roofing in many parts of the world, including England in centuries past.

The story goes that small animals and even family pets or stray cats and dogs would take shelter from inclement weather in the thatching of English homes (5). If the rain came down hard enough they would slip and fall out, thus making it seem to rain cats and dogs (3). This hypothesis seems to have primarily circulated in one of those fun fact emails that used to be so popular (3). It probably has no basis in reality. That small animals like bugs and mice lived in thatched roofs is likely, but to suppose anything as large as cats and dogs did is pretty ridiculous (3). I am embarrassed to admit that I believed this rumor for years nonetheless.

Perhaps trying to find an explanation for this phrase is besides the point, though. One of the more common theories is that the idiom has no complicated origin, but is simply a silly and imaginative phrase that someone came up with to describe heavy rain (2, 3, 4). If we consider some of the idioms in other languages used to refer to such deluges, this starts to make sense. Some, such as “it’s raining buckets” or “jugs” are pretty straightforward, as they suggest water pouring out of a vessel (5). Others are much more creative. Below are some of my favorites (5, 6):

  • Welsh: It’s raining old women and sticks
  • Slovak: Tractors are falling
  • Greek: It’s raining chair legs
  • Spanish: It’s raining toads and snakes
  • Aussie English: It’s a frog strangler

And many, many more of varying degrees of weirdness. Maybe there is a reasonable explanation for why we say it’s raining cats and dogs, as it is outside my window right now. Maybe there’s an explanation for all the strange things people say about the weather. Or maybe there’s no really reason for any of it besides human creativity. Probably no one will ever know for sure. Personally, I’m glad there aren’t any tractors falling.

Works Cited

  1. Liberman, A. (2007, March 21). Raining cats and dogs. Oxford University Press Blog. https://blog.oup.com/2007/03/raining_cats_an/
  2. Quinion, M. (2007, December 29). Raining cats and dogs. World Wide Words. http://www.worldwidewords.org/qa/qa-rai1.htm/
  3. Martin, G. (n.d.). Raining cats and dogs. The Phrase Finder. https://www.phrases.org.uk/meanings/raining-cats-and-dogs.html
  4. Brasch, R. and Brasch, L. (2006). How did it begin: The origins of our curious customs and superstitions. HarperCollins Australia.
  5. Ager, S. (n.d.). It’s raining cats and dogs. Omniglot. https://www.omniglot.com/language/idioms/rain.php
  6. Raining cats and dogs. (2020, August 15). In Wikipedia. https://en.wikipedia.org/wiki/Raining_cats_and_dogs

Published August 16th, 2020

Updated December 7th, 2020

Cat Care

In Search of the Best Cat Food, Part IV: Grain-Free, L.I.D., & Raw Diets

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Meredith Hemphill

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Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

There are trends in pet food just like there are among humans. Increasingly, there has been a movement toward more “natural” pet foods. The idea is to feed pets a diet in line with what they would eat in the wild or what their ancestors ate. However, as my mother is fond of saying, arsenic is natural, too. We need to look past the marketing and make sure that these diets are really all they’re cracked up to be.

Grain-Free Diets

Photo by Nick Fewings on Unsplash

Grain-free diets are fairly self-explanatory. They contain no grains, i.e. wheat, corn, oats, rice, or any other crop in the group. These foods are also gluten-free, but not all gluten-free cat foods are grain-free, as gluten is a protein found in wheat, so other grains may still be included in some gluten-free diets. The concept behind grain-free cat food is that cats, as obligate carnivores, would not include grains in their native diet, which is mostly true. Cats would not chow down on grains in the wild, but they do eat their prey in its entirety, including the stomach contents, which can certainly include grains or other vegetation. The argument that a high-carbohydrate diet is unhealthy for cats still stands nonetheless, and this has largely been the appeal of grain-free cat food.

A Tufts University Study compared 35 grain-free dry cat diets to 42 regular dry cat diets and found that the average carbohydrate content of the grain-free diets was 12 g/1000 kcal lower (1). The individual carbohydrate contents varied widely, however, so it depends a lot upon the food in question (5). The carbohydrate levels are not all that matters, however. Cats are known to be able to digest grains and obtain nutrition from them (2, 3). Considering that cats evolved eating lots of rodents and rodents eat lots of grains, this makes sense.

Grain-free foods don’t simply ditch the carbohydrates–they replace the grains with starchy vegetables like potatoes, lentils, cassava, or peas. There isn’t much research on how digestible these plants are or how bioavailable their nutrients (3). At least some cats get gastrointestinal symptoms from consuming them (4, 5).

Some owners may choose grain-free diets over concerns about food allergies. But food allergies are uncommon in cats. A 2018 study found that only 0.1% of cats had them (10). When food allergies do develop, it is usually to animal products like beef or dairy, not plants (2, 3, 4). Gluten intolerance has not been documented in cats, so that’s no reason to avoid grains (3). Obviously, if your cat really does have a documented allergy to a grain, then you want to make sure their diet is at least free of that grain. If you suspect an allergy, talk to your veterinarian before you do anything else.

I would be remiss if I didn’t mention the concerns about grain-free diets and heart problems that have been brought up in the last several years. Although the connections are primarily being investigated in dogs, it has been impossible not to wonder if there is reason to be worried about cats. Around 2017-18, veterinarians began to raise concerns over cases they saw of dogs fed grain-free diets developing dilated cardiomyopathy, a form of heart disease causing an enlarged heart (6).

The US Food and Drug Administration (FDA) decided to investigate, and they still are. It’s thought that taurine deficiency might play a part, and diets containing legumes or potatoes as the primary carbohydrate might be the culprits, but it remains unclear (7). There were only a handful of reports on cats, so the FDA chose to focus on dogs, and there has been no further word on whether there may be a link between a grain-free diet and heart problems in cats (6).

Grain-free diets, at least the way they are manufactured today, are probably not as beneficial as we may have been led to believe. They may even be harmful, although more research will have to be done for us to know for sure. I’ll admit, I used to be one of those people who thought I had to feed my cats grain-free food. It sounds so much healthier for them! But that’s what marketing is for, isn’t it?

Limited Ingredient Diets

Limited ingredient diets, or L.I.D., are not just one thing. L.I.D. is a bit of an umbrella term, encompassing a group of diets that have a narrower range of ingredients than usual. They are generally meant for cats with known or suspected food allergies, and in fact they can be helpful for such cats. L.I.D. often contain only single protein and carbohydrate sources, i.e. lamb and rice or salmon and potato (8, 9). This makes is easy to be sure that a cat with food allergies or sensitivities is not eating an ingredient they are allergic to.

Novel source of protein? – Image by sven kopping from Pixabay

Many L.I.D. are made with “novel” sources of protein and/or carbohydrates that pets are unlikely to have encountered before, and therefore probably won’t have developed an allergy to (8, 9). These range from the rather mundane–duck, rabbit, sweet potato–to the very out in left field–alligator, kangaroo (8, 9). L.I.D. may also be used as part of a series of elimination diets to figure out what a cat with suspected food allergies is allergic to, under veterinary supervision (9).

Aside from cats with food allergies, some L.I.D.s may be helpful for cats with sensitive digestion as well (8). Otherwise, there is really no particular need for a healthy cat to be on a L.I.D. If you think your cat might benefit from one, especially if you suspect your cat may be suffering from allergies, talk to your veterinarian about it. Most cats with allergies are allergic to fleas or something else in their environment, not their food (10). If food allergies are suspected, there is a long process of testing via elimination diets to determine what, if anything, in the diet your cat is allergic to (9).

Raw Diets

This is a tough nut to crack. While I was doing my research, I read a particular article which was harshly critical of raw diets for cats. One of the drawbacks they listed was that there has been very little research done on these diets. As someone who was lately a research scientist, I kind of want to bash my head against a wall. The solution to a lack of research is to do the research, not to declare that the under-researched thing is bad.

But the fact that there is currently a lot of anecdotal information and not much in the way of scientific studies is a lot of the problem with raw diets, I think. It’s difficult to decide whether the proponents or the detractors have the firmer position because both have only a handful of studies to back them up. The rest is a matter of logic, tangential information, and beliefs.

Before we go any further down this rabbit hole, let’s talk about what a raw diet is. The definition can be a bit variable, but the basic principle is that the food is made of uncooked ingredients. A raw pet diet is mostly muscle meat, organs, ground bone, eggs, and sometimes vegetables, fruits, and dairy (11). Some people make homemade raw diets, but they can be purchased in a variety of forms as well. The goal is to simulate the natural diet of the pet, or its ancestors in the case of dogs, which are highly domesticated animals and don’t really have a natural diet. For cats, their diet in the wild, ideally, is whole prey animals like mice, birds, fish, and small reptiles.

Image by A_Different_Perspective from Pixabay

Proponents of raw diets for cats say that raw meat is more nutritionally sound, having not been exposed to heat that might break down or alter nutrients, and it’s more biologically appropriate for cats anyway (12, 13). They claim that the diet can prevent or alleviate many feline ailments (13, 14). The evidence for this remains anecdotal, but this will necessarily be the case until rigorous research is done to investigate. Nonetheless, some veterinarians have begun to recommend raw diets based on their experience with them, but most fall into the other camp.

The detractors of raw diets, and there are many, say that raw diets are dangerous and have no major benefits. The American Veterinary Medical Association, American Animal Hospital Association, Companion Animal Parasite Council, and Centers for Disease Control have all taken a position against feeding pets raw diets (15). The primary concern is food-borne infections. This is the reason public health authorities tell us humans not to eat undercooked meat and to carefully avoid cross-contamination. Raw food, especially raw animal products, can carry bacteria and parasites. And studies have shown that raw pet foods do (12, 15), which is to be expected, really. The professionals who decry raw pet foods take the position that the risk of disease to both pets and humans outweighs what little benefit, if any, they see in these diets.

Even here there are two sides: those in favor point out that cats, being carnivores, have short, acidic digestive tracts designed for digesting meaty meals without allowing pathogens to proliferate in their guts (13, 14). Not to mention that cooked pet foods have been found to be contaminated with pathogens or toxins before, so perhaps to say raw foods are unsafe draws a false comparison (13)? That’s another case where I doubt anyone has crunched enough data to be sure. Even raw diet cheerleaders readily say that owners need to be careful not to give themselves food poisoning if they feed their cats a raw diet. Using proper food-handling technique should prevent any problems. It’s also important to dispose of uneaten food promptly and cleaning and sanitizing the food dish, as well as the area around it if any food gets on the floor.

Is raw food a good idea for your cat? In general, there’s so little concrete information that it’s hard to say. My instinct is that cats are carnivores, so it should be fine, as long as the diet is well-balanced. It needs to be either an approved commercial diet (AAFCO-approved in the United States) or a homemade diet using a recipe designed by a veterinarian or veterinary nutritionist. If you are thinking about going the homemade route, be very careful about looking for recipes on the internet, because there are lots of them, and many are just made up by people with cats, not experts in cat nutrition.

Also, some cats and some households should not use raw diets. Cats on immunosuppressants (like chemotherapy drugs) or high doses of steroids should not be feed raw food diets, as their immune systems may be more vulnerable to the pathogens in raw animal products (13). Households with very young children or elderly people, or anyone with a compromised immune system, probably shouldn’t use a raw cat food, either (11, 12, 13). Pathogens from their food can pass into a cat’s stool and even remain on the cat, especially on their face, in addition to the aforementioned concerns of pathogens being on food prep and feeding surfaces (12). In a home where there are people–or pets–with weak immune systems, this could be very dangerous. The jury may be out on raw diets in general, but there is definitely a subset of households where they will never be appropriate.

Works Cited

  1. Prantil, L.R., Heinze, C.R., and Freeman, L.M. (2017). Comparison of carbohydrate content between grain-containing and grain-free dry cat diets and between reported and calculated carbohydrate values. Journal of Feline Medicine and Surgery, 20(4), 349-355. https://journals.sagepub.com/doi/full/10.1177/1098612X17710842
  2. Freeman, L.M., Linder, D.E., and Heinze, C.R. (2016, June 14). Grain-free diets: Big on marketing, small on truth. Petfoodology. https://vetnutrition.tufts.edu/2016/06/grain-free-diets-big-on-marketing-small-on-truth/
  3. Cats Only Vet Hospital. (2019, June 3). Grain free and other marketing trends. https://catsonlyvethosp.com/grain-free-other-marketing-trends/
  4. Buzhardt, L. (n.d.) What’s in my cat’s food?: Designer diets, grain free diets. VCA Hospitals. https://vcahospitals.com/know-your-pet/whats-in-my-cats-food-designer-diets-grain-free-diets
  5. Heinze, C.R. (2017, July 3). Research update: New insight into grain-free cat diets. Petfoodology. https://vetnutrition.tufts.edu/2017/07/research-update-new-insight-into-grain-free-cat-diets/
  6. Cats Herd You. (2018, August 22). What do grain-free pet food warnings mean for cats? https://catsherdyou.com/what-do-grain-free-pet-food-warnings-mean-for-cats/
  7. US Food and Drug Administration. (2018, July 12). FDA investigating potential connection between diet and cases of canine heart disease. https://www.fda.gov/animal-veterinary/cvm-updates/fda-investigating-potential-connection-between-diet-and-cases-canine-heart-disease
  8. LID diets for dogs and cats. (2017, June 26). Pet Central, Chewy. https://petcentral.chewy.com/lid-diets-dogs-cats/
  9. Anderson, K. (2020, July 2). Meals that heal: The best food for cats with allergies. The Dog People, Rover. https://www.rover.com/blog/best-food-cats-with-allergies/
  10. Burns, K. (2018, June 27). Banfield: Few pets allergic to food; flea, environmental allergies rise. American Veterinary Medical Association. https://www.avma.org/javma-news/2018-07-15/banfield-few-pets-allergic-food-flea-environmental-allergies-rise
  11. Association of American Feed Council Officials. (2012). Raw foods. https://talkspetfood.aafco.org/rawfoods
  12. Stregowski, J. (2020, April 30). Should you feed your cat a raw diet? The Spruce Pets. https://www.thesprucepets.com/raw-food-diet-for-cats-552329
  13. Tasi, A. (2020, January 6). Feeding raw: A veterinarian’s view. The Conscious Cat with Ingrid King. https://consciouscat.net/2020/01/06/feeding-raw-a-veterinarians-view/
  14. Pierson, L.A. (2016, November). Feeding your cat: Knowing the basics of feline nutrition. Cat Info. https://catinfo.org/#Home-Prepared_Diets
  15. Paul, M. (2014, September 24). The dangers of a raw diet for your cat. Pet Health Network. http://www.pethealthnetwork.com/cat-health/cat-diet-nutrition/dangers-a-raw-diet-your-cat

Published August 9th, 2020

Updated October 29th, 2020

Breed Profiles

Scottish Fold: Charming but Controversial

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Meredith Hemphill

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Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

Brown tabby cat with folded ears
Image by Elena Borisova from Pixabay

If you ask someone to draw a cat, they would probably give it a head with two triangular ears on top. If they draw as well as I do, a circle and two triangles might be all you get. But not all cats have perky ears. The Scottish Fold breed only exists because one barn cat’s flattened ears made her stand out.

William Ross was a shepherd, but he was also a cat fancier. He and his wife bred British Shorthairs. In 1961, he was visiting the McRae farm in the Tayside region of Scotland when he noticed something peculiar about one of the barn cats. Her name was Susie, and she was a white she-cat with strange ears that folded forward and down on her head. Ross thought this unusual trait might be the makings of a new breed, so he asked the McRae’s if he could buy Susie. They reached a compromise: instead, he could have the pick of Susie’s first litter. When the time came, Ross took home a white female kitten he named Snooks and subsequently used his own British Shorthairs to found a new breed.

The Rosses originally called the breed lop-ears, thinking of lop-eared rabbits, but they later decided on the current name in honor of the cats’ country of origin. The breed reached the United States in the early 1970s, and by now it is popular around the world. It remains a rare breed. All true Scottish Folds are still descended from Susie via Snooks, so there hasn’t been long to build up a large population from that single breeding line, and they can be difficult to breed for genetic reasons.

Breed Characteristics

Of course, the thing that Scottish Folds are known for is their folded ears, but actually not all of them have this trait. The ear folding is caused by a spontaneous mutation affecting the development of cartilage (1). The mutation is incompletely dominant, so kittens only need one copy of the mutation to have folded ears, but the presentation of the trait may be intermediate. As such, there are three degrees of ear folding: single, double, and triple. The single fold bends forward about halfway up the ear and doesn’t hug the head, while the double and triple folds are progressively tighter (2). The triple fold is most desirable for show cats (2).

Gray cat with vase of roses
Scottish Folds have a habit of lounging in unusual positions – Image by Paul Faerstein from Pixabay

When a Scottish Fold doesn’t inherit the ear folding mutation, they will have straight ears. Sometimes straight-eared Scottish Folds are acceptable for showing under a different name, but many organizations don’t accept them (2). They are an important part of breeding programs (3), however, and are often sold as pets for a cheaper price than their folded-ear compatriots (2). Breeders won’t know which kittens have which ears until about three to four weeks of age, though, because all Scottish Folds are born with straight ears that later droop down–or not.

Regardless of ear type, all Scottish Folds are medium-sized cats with a stocky body and round head. They have large, wide eyes which probably contribute to the notion that the folded-ear cats look like owls. Scottish Folds have somewhat short muzzles and legs. They may have short or long fur and be any color or pattern except point.

Scottish Folds are playful, moderately active cats that are known for being quiet and sweet. They are people-oriented but typically get along well with other pets, too, as well as children. Although they like attention, they aren’t so much a clingy breed. They are laidback and adaptable, the kind of cat that can roll with the changes.

Scottish Folds Acting Silly

Health Concerns

Scottish Folds were first recognized as a breed by the Governing Council of the Cat Fancy (GCCF) in the United Kingdom in 1966, but only five years later the GCCF banned further registry of the breed (2). They still don’t recognize the breed (4). In 2017, the British Veterinary Association called for the breed to be banned outright (4). The cause of all this is concerns over the health and welfare of the cats.

All pedigree cats have higher incidences of some diseases. The question is whether the characteristic of folded ears which Scottish Folds are bred for inherently leads to suffering. At first, the GCCF stopped registering Scottish Folds over concerns that the folded ears caused a risk of ear mites, ear infections, and deafness, but this is now believed to be untrue (2). However, there are demonstrated health problems associated with the mutation in cartilage development that causes the ear drooping, and this has led to the continuing controversy about the breed.

The disease associated with the folded ear mutation is called osteochondrodysplasia. It is a disorder of abnormal bone and cartilage development which leads to arthritis and can be debilitating (1). It primarily affects the tail and leg joints from the knees down (1). The British Veterinary Association says that all Scottish Folds with folded ears will suffer from osteochondrodysplasia to some degree during their lifetime (4), and there are studies that back this up.

A study that examined the inheritance of the disease in Scottish Folds did find that all cats with folded ears had the disease (5). On the other hand, cats in the study with mild osteochondrodysplasia did not present symptoms (5). Of course, with cats, it’s sometimes hard to tell. Another study which examined Scottish Folds in clinics and a cattery also came to the conclusion that this is a breed-wide problem and recommended not breeding folded-ear Scottish Folds (6).

Image by cat-cheng from Pixabay

Some think the problem has been blown out of proportion. The BBC quoted a woman who has been breeding Scottish Folds for over a decade: “If I had discovered there had been a significant problem I would certainly have stopped breeding them” (4). And you would certainly hope this would be the case. Scottish Folds are usually crossed to British Shorthairs, American Shorthairs, or Scottish Folds with straight ears in breeding programs to limit any health problems (7). Cats with two copies of the folded-ear mutation are more likely to have severe skeletal problems (8).

To Have and to Fold

Scottish Folds are without doubt charming and easy-going cats. Whether their genetic health problems are any worse than those faced by other pedigree cats is still controversial. If you are interested in a Scottish Fold, the only special grooming needs they have are frequent checks inside the ears and a cleaning if you find it dirty–for the folded-ear cats, that is. Much of the appeal of the Scottish Fold has been the cuteness factor of the folded-ear cats, but don’t dismiss the straight-eared ones out of hand. They have the same sweet, chill personality and are eager to have forever homes, too. Check out Scottish Fold Rescue to look for Scottish Folds that need adoption in the United States.

Fun Facts

  • Taylor Swift is the proud parent of two Scottish Folds named Meredith Grey and Olivia Benson. They’re quite the Instagram stars. (9)
  • Susie was not the first cat to have folded ears. The earliest record of one was in 1796, when an English sailor brought one home from China. (7)
  • Long-haired Scottish Folds are sometimes considered a separate breed called the Highland Fold (2).

Works Cited

  1. International Cat Care. (2018, September 5). Scottish Fold disease – osteochondrodysplasia. https://icatcare.org/advice/scottish-fold-disease-osteochondrodysplasia/
  2. Petfinder. (n.d.). Scottish Fold. https://www.petfinder.com/cat-breeds/scottish-fold/
  3. Cat Fanciers’ Association. (n.d.). About the Scottish Fold. https://cfa.org/scottish-fold/
  4. Brocklehurst, S. (2017, April 27). Should Scottish fold cats be banned? BBC Scotland. https://www.bbc.com/news/uk-scotland-39717634
  5. Takanosu, M., et al. (2008). Incomplete dominant osteochondrodysplasia in heterozygous Scottish Fold cats. Journal of Small Animal Practice, 49(4), 197-199. https://www.mendeley.com/catalogue/49b03dae-ac50-3c53-96f5-f1281561939d/#
  6. Malik, R., et al. (1999). Osteochondrodysplasia in Scottish Fold cats. Australian Veterinary Journal, 77(2), 85-92. DOI: 10.1111/j.1751-0813.1999.tb11672.x
  7. Hill’s Pet. (n.d.). Scottish Fold cat information and personality traits. https://www.hillspet.com/cat-care/cat-breeds/scottish-fold
  8. UC Davis Veterinary Genetics Laboratory. (n.d.). Scottish Fold. https://vgl.ucdavis.edu/test/scottish-fold
  9. Cook, J.R. (2019, July 10). They’re beauty, they’re grace…a guide to Taylor Swift’s absolutely adorable cats. Life and Style. https://www.lifeandstylemag.com/posts/guide-to-taylor-swifts-cats-meredith-olivia-and-benjamin/
  10. Cat Time. (n.d.). Scottish Fold. https://cattime.com/cat-breeds/scottish-fold-cats#/slide/1

Published August 2nd, 2020

Updated October 29th, 2020

Cat Care

In Search of the Best Cat Food, Part III: Kitten, Adult, & Senior Diets

mehshadoweye

Meredith Hemphill

mehshadoweye

Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

The pet food industry offers diets for every stage of a cat’s life, from formula for newborn kittens to senior cat food. The kitten milk-replacement is one thing, but what’s the difference between solid food for kittens, adults, and seniors? And what about the cat food that says it’s for “all life stages”? Today we look at the difference between diets for the various life stages and what really matters for your cat.

Cat and two kittens eating from bowls
Image by mariahuusgaard from Pixabay

Kitten Food

Before doing this research, I knew there was at least one difference between kitten food and any other cat food. I took Joon in when she was about four months old, and I was living with a roommate that already had a cat. Domino is a gorgeous tuxedo cat with spooky yellow eyes, and she was quite pudgy. My roommate had to put her on a diet, and Domino was not a fan. She kept eating Joon’s food, which Joon was too busy playing to care about. My vet told me I should be careful to keep her from doing this, because kitten food is high in calories.

It makes sense, doesn’t it? Kittens are still growing rapidly, and as they get older they use up a lot of energy playing as well. In fact, kittens may need up to three times as many calories as an adult cat each day (1, 2, 3)! And they have higher protein requirements than adults, as well, needing to get about 30% of all that energy from protein (2). Most of the rest of the calories need to come from fat to ensure that they get enough essential fatty acids for proper development (1). Kittens need lots of vitamins and minerals as well. Basically, like all babies, kittens need lots of nutrients in their diet so they can grow up big and strong. So kitten food is made more nutrient-dense than adult food.

The Association of American Feed Control Officials (AAFCO) requires kitten food to be at least 30% protein and 9% fat on a dry matter basis (4). A survey of 212 adult and kitten foods by IdleCat found that kitten foods actually averaged 40.77% protein for kibble and 49.11% protein for canned food (3). The fat content was a little closer to the minimum recommendation, but for both kinds of food was more than 21% higher than the average fat content of the adult foods (3). Carbohydrate and fiber content were lower to compensate (3). Vitamins and minerals weren’t measured in that survey, but in a well-balanced kitten food they should be present in higher amounts as well.

Kitten food is also made to be easier for small mouths with developing teeth to eat. Canned kitten diets are typically softer, and the kibble comes in smaller pieces (1). However, the nutritional differences are what is most likely to impact a cat’s health. Adult cat food is usually not nutrient-dense enough for kittens, although it will do temporarily in a pinch (5). Conversely, as my vet told me, kitten food can cause adult cats to gain too much weight. Depending on the nutrients included, the extra vitamins and minerals could even cause toxicity in an adult cat (1). A few bites here or there is unlikely to cause anybody any harm–Domino is certainly none the worse for it–but kittens need kitten food and adults should be kept away from it as best we can.

Cats are considered kittens up to one year of age, with the exception of some large breeds. Maine Coons do not reach maturity for up to two years. If you are unsure how long to keep feeding your cat a kitten diet, check with your veterinarian.

Tortoiseshell cat eating from bowl
Image by sweetlouise from Pixabay

Adult Cat Food

Adult cat foods are formulated to maintain a grown cat’s weight and health. Growth and development never completely stop. All organisms continue to make new cells, repair damaged tissues, and progress through their life cycle as long as they live. However, an adult cat uses much less energy than a kitten to do these things, so they need far fewer calories and other nutrients relative to their body weight. This is reflected in the nutritive content of adult cat food.

The AAFCO divides their standards for cat food into two categories: “growth and reproduction,” for kittens and pregnant or lactating queens, and “adult maintenance” for the average, older, and sterilized adult cat (6). The minimum protein content for adult maintenance is 4% lower than the recommendation for kittens and queens. The fat minimum is the same, but 5 out of 12 mineral recommendations are lower for adults, as well as Vitamin A (4). These minerals and vitamin can cause toxicity in excess, which is more likely in adult cats who use less of the nutrients than a growing kitten or a queen who is growing kittens.

Cats are typically considered “adults” from the age of one year to seven years, although this varies some by breed and individual cat (7). Those of us with rescue cats often don’t know exactly how old they are, so you and your vet may have to play it by ear to decide when the time seems right to start treating your cat like a senior.

Senior Cat Food

In the United States, the AAFCO is the government body responsible for licensing pet food, and as previously indicated, they don’t issue standards for senior cat food. The consequence of this is that senior cat food is very similar to adult cat food, with some slight modifications that won’t color outside the AAFCO adult cat food guidelines (8). Whether this is a bad thing or not is hard to say. A lot remains unknown about the needs of senior cats. Due to lack of research, many of the decisions made about how to feed senior pets have been made based on what is known about aging humans (9). Even so, there have been improvements in senior cat diets over the years.

But some cats may not need to go on a senior diet at all, or not until much later in life. If an older cat is keeping up their body weight and muscle condition on their adult diet, there’s no need to change them to a senior diet (8). If a senior kitty begins to gain or lose weight or lose muscle mass and no associated health problem is found, a change in diet may be in order (8). However, senior cat diets can be pretty different from one another. Of course, cats with age-related health problems may be put on a diet specific to their needs. If your vet recommends just plain senior cat food, however, the variability in formulations can be overwhelming.

Fat tortoiseshell cat
Cats sometimes gain weight as they get older – Image by Quinn Kampschroer from Pixabay

It used to be the case that senior cat food was low protein, low fat, and high fiber (8), and the myth that senior cats need a diet low in protein still persists. Some health conditions may call for a low-protein diet, but a normal senior cat may suffer greater muscle loss with less protein (9).

Whether or not senior cats need more protein than adult cats is still unclear, however, and may depend upon the individual cat. If they are notably losing muscle mass, then a high-protein senior diet may be the solution (10). There are still senior diets made with low amounts of protein, all the way to those with enhanced protein, so it pays to check the label. Remember that it’s the dry weight of the nutrients that you need to compare, as the amounts on pet food labels are given in minimum and maximum percentages instead of absolute quantities. Check out this page for a rundown of how that math works.

Senior formulas may be low-calorie, hence the traditional wisdom of making them high-fiber, and for some cats this is appropriate. Generally, cats tend to have progressively slower metabolisms up to eleven years of age and are prone to obesity during middle age, around years six to eight (11). Once they get older than that, they often start to lose weight and may need high calorie diets (11).

Sometimes a vet may actually put a senior cat on a kitten diet if weight loss is a major issue, simply to get enough calories into them (8). In milder cases, a more calorie-dense senior food may be the way to go. If your cat has the opposite problem, well, low-calorie is where it’s at. Both obesity and being underweight can cause significant health problems or be symptoms of them, so keep a close eye on the body condition of older cats. If something changes, always have a vet check for disease before trying to treat the problem with diet alone.

There are other variables as well, such as dietary phosphorous and sodium, which sometimes matter for senior cats if they have certain health problems (9). If your cat has any health issues but they don’t require a medical diet, ask your veterinarian if there is anything you should be on the lookout for when choosing their food.

All Life Stages Cat Food

In order for a pet food to claim that it is “complete and balanced” for all life stages, it must meet the standards set by the AAFCO for both the growth and reproduction and adult maintenance stages. Because the minimums for certain nutrients are higher in the growth/reproduction stage, and there are only a few maximums, “all life stages” food may be too nutrient-dense for some adult cats (12). The food has to have enough nutrients for every stage of life, so it makes sense that what you end up with is more like the food intended for kittens and queens. They have higher nutrient requirements.

Opinions are divided, but I found that veterinarians seemed most inclined to think that food for all life stages was really not appropriate for adult or senior cats (12, 13). Pet food companies had the more mixed advice. Personally, I think all life stages food is great for keeping on hand if you find a stray cat or kitten you need to assist, as you never know what age they might be, and the extra nutrients are probably not a bad idea. It’s not what I would feed my cats at home, though.

Works Cited

  1. Paretts, S. (n.d.). What is the difference between kitten and cat food? The Nest. https://pets.thenest.com/difference-between-kitten-cat-food-6832.html
  2. ASPCA. (n.d.). Cat nutrition tips. link here
  3. John, B. (2019, November 19). Kitten food vs. adult cat food: What are the differences? IdleCat. https://theidlecat.com/kitten-food-differences/
  4. Association of American Feed Control Officials. (2014). AAFCO methods for substantiating nutritional adequacy of dog and cat foods: Proposed revisions edited per comments for 2014 official publication. PDF
  5. Syufy, F. (2019, November 4). How to choose the best kitten food. The Spruce Pets. https://www.thesprucepets.com/choosing-best-kitten-food-552267
  6. US Food and Drug Administration. (2020, February 28). “Complete and balanced” pet food. link here
  7. Chewy Pet Central. (2019, November 13). Cat food for all ages: How (and what) to feed your cat during every stage of life. https://petcentral.chewy.com/ages-stages-cat-food/
  8. Chewy Pet Central. (2019, December 10). The best senior cat food: A guide to feeding your older cat. https://petcentral.chewy.com/best-senior-cat-food/
  9. Freeman, L.M., Linder, D.E., and Heinze, C.R. (2016, March 8). When should I switch my pet to a senior diet? Tufts Clinical Nutrition Service. https://vetnutrition.tufts.edu/2016/03/when-should-i-switch-my-pet-to-a-senior-diet/
  10. Pittari, J., et al. (2009). American Association of Feline Practitioners: Senior care guidelines. Journal of Feline Medicine and Surgery, 11(9), 763-778. https://doi.org/10.1016/j.jfms.2009.07.011
  11. PetCoach. (n.d.). Do senior cats have different nutritional needs? https://www.petcoach.co/article/nutritional-needs-of-senior-cats/
  12. Coates, J. (2014, April 25). Are life stage dog foods credible? PetMD. https://www.petmd.com/blogs/nutritionnuggets/dr-coates/2014/april/debate-over-all-life-stage-dog-foods-31604
  13. Rock Veterinary Clinic. (n.d.). Understanding pet food labels. https://www.rockvetclinic.org/post/understanding-pet-food-labels.html

Published July 26th, 2020

Updated November 1st, 2020

Behavior

Why do cats bring home “gifts” of dead animals?

mehshadoweye

Meredith Hemphill

mehshadoweye

Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

Gray tabby cat holding mouse
“You know who would love this? My human!” – Image by Kurt Bouda from Pixabay

One summer morning when I was in high school, I opened the front door of my parents’ house to go get the mail. Fortunately, I’m in the habit of looking down when I walk, so I managed to avoid planting my bare foot directly into the present that our outdoor cat, Rosenberg, or Rosie, had left on the doormat for us. It was a baby rabbit, or most of one, that is. She had eaten a hole in the side of the head and consumed the brain, but left the rest for us to enjoy. We still call Rosie a zombie cat.

This was not the only time Rosie left us a gift. She’s never brought anything more indoors than the garage, but many people are not so lucky. Sometimes, cats bring gifts that are not so decidedly deceased, either, and cat owners may find themselves chasing rather lively birds, rodents, or reptiles around their homes. We humans generally regard this behavior as disgusting, but our cats seem to think we appreciate it. Why? Just, why?

Humans and cats are obviously very different animals, and we think differently. Cats are hard-wired to hunt, and a lot of their emotional lives revolve around hunting. It’s what they would spend most of their waking hours doing in the wild. Cats simply enjoy hunting. If prey is available, cats will hunt even if they are well-fed. A study found that cats would stop eating in order to kill a rat that was presented to them, only to set the rat beside their food bowl and keep eating what they had been eating before (1).

Cats may have evolved this high prey drive because prey can be scarce and difficult to catch, so stopping whatever they’re doing to hunt available prey, even when not hungry, would have boosted their chances of survival (1). The feline drive to hunt is why cats with access to the outdoors will inevitably at least attempt to. There are a few theories as to why they want to bring some of their prey to their people, however.

One school of thought is that they simply want to bring their prey back to a safe place to consume it, their den as it were, the way they would in the wild (2). But their den is your home or front stoop. Some experts believe that cats may want to show off their good work, but veterinarian Dr. Stephanie Liff points out that pride for their catch may be too human a motivation to ascribe to cats (3).

Tabby kitten playing with plush toy
Kittens have to practice hunting – Image by Ivo Zahradníček from Pixabay

Although cats are usually thought of as solitary and independent animals, they are actually fairly social and often live in colonies or with family members (4). As such, feral cats may bring prey back to the group to ensure the survival of everyone (5, 6). Cats also hunt cooperatively with members of their social group–Elizabeth Marshall Thomas suggests in her book The Tribe of Tiger that a possible explanation for bringing home live prey, at least for some cats, might be the joy of joining in a group hunt with the humans as they frantically chase down the injured animal (4). Domestic cats may be thinking in these terms when they bring prey to us, their family members of another species. Or, they may be thinking of us as family in a filial sense.

Perhaps the greatest consensus for why cats bring their humans prey is that they are treating us like their kittens. Mother cats bring prey to the den to feed their offspring. They also bring home dead, dying, or wounded prey to teach their kittens how to hunt. So our cats may be trying to feed us or teach us, or both. Really, who could blame them? In their world, hunting is everything. But we are clumsy, ungainly things that clearly cannot hunt for ourselves. Who knows where they think we get our food from, but I imagine they pity us sometimes. So perhaps they want to do what they can to help.

Elizabeth Marshall Thomas shares a story about how she and her husband had a she-cat that began to bring home dead mice all the time after she had a kitten (4). She would bring mice for the kitten, even after the kitten became an adult, but she would also bring them to Thomas, her husband, and their dog, the most appreciative of the bunch (4). It was as though motherhood made her suddenly feel responsible for all of these terrible hunters with whom she shared her home. However, even sterilized cats and toms can show this behavior. Maybe they all feel sorry for us.

Even indoor-only cats will bring gifts. They may manage to catch prey that sneaks indoors to present to you, but more often their gifts are inedible. The prey caught by indoor cats is mostly their toys, or whatever other objects they use as a toy, and these are the things they are likely to leave as gifts (5). Joon does this occasionally at night. I’ll wake up in the morning and find one of her toys, most often her beloved plush, pink-and-white sock, lying right beside me on the bed. If I wanted to have someone teach me how to hunt, it wouldn’t be Joon. I think her lifetime achievements are a spider and some flies. But I appreciate the sentiment.

Gray and white cat holding toy mouse
Not all mice are created equal – Image by isaikina13 from Pixabay

If your cat is leaving gifts more like Rosie’s than Joon’s, and you wish they wouldn’t, there are a couple things you can do, but keep in mind that you may not be able to stop this behavior completely. Cats will always find something to hunt, and there’s always a chance that if they catch something, they will bring it to you.

That being said, one thing you can do is engage your cat in interactive play to satisfy their prey drive and diminish some of that need to hunt live animals. The live prey drive will never go away, but you can redirect some of it. Another tactic is to make sure that any cats with access to the outdoors wear a breakaway collar with a bell, so that their hunts are less likely to be successful. That’s good for the local ecosystem and you’ll get much fewer unwanted gifts.

When your cat does bring you a present you didn’t ask for, you may want to scold them, but don’t. They won’t understand. Whatever the reason your cat is doing this, they see it as at least a neutral and probably a beneficial thing that they are doing for you. How would you feel if you did something really nice for somebody, and they yelled at you and called you a bad person for your good deed? It’s usually recommended that you actually praise your cat and then discreetly dispose of their gift, assuming it isn’t still very much alive and you have other things to worry about at the moment. Your cat is, after all, only doing what is natural to them.

By the way, if you have a cat with access to the outdoors, and they don’t bring you gifts, don’t feel insulted or worried. Not all cats have the same prey drive. Yours may just not feel as compelled to hunt when provided with sufficient food. Or they may not be very good at it. (7) Rest assured, they are still finding ways to be a cat, as cats always do.

Works Cited

  1. Adamec, R.E. (1976). The interaction of hunger and preying in the domestic cat (Felis catus): An adaptive hierarchy? Behavioral Biology, 18(2), 263-272. https://doi.org/10.1016/S0091-6773(76)92166-0
  2. Cutolo, M. (2020, March 26). Why do cats bring home dead animals? Reader’s Digest. https://www.rd.com/article/why-do-cats-bring-home-dead-animals/
  3. Puiu, T. (2017, May 5). Why do cats bring dead animals home to you: You should actually be honored. ZME Science. https://www.zmescience.com/ecology/animals-ecology/why-cats-dead-animals-home/
  4. Thomas, E.M. (1994). The tribe of tiger: Cats and their culture. Simon & Schuster.
  5. Shojai, A. (2019, November 19). Why do cats bring ‘gifts’ of dead animals? The Spruce Pets. https://www.thesprucepets.com/cat-hunting-gifts-553946
  6. Primm, K. (n.d.). Ask a vet: Why does my cat bring me dead mice? I Heart Cats. https://iheartcats.com/ask-a-vet-why-does-my-cat-bring-me-dead-mice/
  7. Argos Pet Insurance. (2014, September 10). Why do cats bring their owners dead animals? https://www.argospetinsurance.co.uk/we-talk-pet/are-cats-really-bringing-their-owners-presents-when-they-bring-mice-home/

Published July 19th, 2020

Updated November 10th, 2020

Cat Care

In Search of the Best Cat Food, Part II: Wet or Dry?

mehshadoweye

mehshadoweye

Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

White cat eating dry cat food
Image by Deedee86 from Pixabay

There is a head-spinning variety of cat foods out there, but the most basic distinctions can be drawn based on moisture content. Dry cat food, the familiar dehydrated kibble, contains 6-10% water (1, 2). Semi-moist food is 15-30% water (2). Canned food has a moisture content of at least 75% (1, 2). Generally speaking, the higher the moisture content, the higher the price and the lower the convenience, so dry food is a very popular choice. But is it the best choice for our cats’ health?

Because kibble is already dehydrated, it doesn’t dry out if left in the bowl for long periods of time, so it lends itself to the convenience of free-feeding. Cats usually like to eat lots of small meals, and let’s face it, people like to be lazy, so this arrangement is often mutually agreeable. We’ll discuss in another part of this series why free-feeding may not be ideal, at least for some cats, but regardless it is often what busy people resort to, and dry food makes that easy. Dry food can also be bought in bulk and will last a long time if stored properly in a cool, dry place. And, again, it’s usually cheap.

Human concerns are not the only reason why someone would feed their cat dry food, however. It has long been thought that kibble helps clean cats’ teeth, preventing and/or treating dental disease. Veterinarians sometimes recommend it for this purpose (3). The idea is that chewing the hard bits of kibble mechanically scrapes the teeth clean of plaque buildup (3), and there has been some scientific evidence supporting the idea that dry food does, in fact, prevent periodontal disease (4). More widely, however, the evidence does not support the idea that dry food cleans cats’ teeth, and there is good reason why it wouldn’t (3).

As mentioned in part one, cats are obligate carnivores. They evolved to eat meat exclusively. As such, their teeth are made for biting and tearing, not chewing (3). Plant matter includes tough cell walls that need to be broken down, so animals that are meant to eat plants do a lot of chewing (3). Carnivores just bite off manageable chunks and swallow them whole (3, 5). That is usually what cats do with kibble. They swallow it whole. Sometimes they bite the kibble, but when they do, the hard but brittle kibble shatters on the biting edges of the teeth and doesn’t do anything to scrape the teeth clean (3, 6).

Yawning gray tabby cat
These chompers aren’t for chewing – Image by Martina Misar-Tummelsthammer from Pixabay

As far as the nutrition of dry food goes, it isn’t great news, either. Dry cat food is typically high in carbohydrates, on average 35-50% by calories (6). Cats neither need carbohydrates, nor can they digest them well, due to their biology as obligate carnivores. They need a diet high in animal protein with a moderate amount of fat (see part one).

Not all dry foods are created equal, of course, but even grain-free dry foods can still be high in carbohydrates if they simply replace grains with potatoes or peas (6). It’s also common for much of the protein in dry food to come from plant matter, but plant proteins do not contain all of the amino acids that cats need (6). The missing nutrients are supposed to be added back in, otherwise the food won’t meet required nutrition standards, but pet nutritionists are still learning exactly what cats need.

With all that being said, is dry cat food just the worst? Well, no, trying to make a cat vegan or feeding them a diet of human food would probably be the worst. When I looked up veterinarian opinions on whether dry or wet food was better, there were mixed opinions. Some were adamant that cats should only be fed canned/wet food (i.e. 3, 6). Others said it didn’t matter (i.e. 5), or it depended upon the cat. I didn’t come across anyone who was a staunch defender of dry food, but there were definitely professionals who had no quarrel with it. I’ll touch on semi-moist food at the end, since it is kind of a weird middle ground, but first let’s take a look at wet food.

Wet food, which as far as I know only comes in cans, can vary in quality but is always notable for its high water content, up to 84% (7). Cats should consume about 20-70 ml of water per kg of body weight per day (8). But cats are descended from Felis lybica, a desert wildcat, so they have a low thirst drive. They tend to obtain most of their water from their food. Prey would normally contain 70-75% water (6). Studies have demonstrated that cats can avoid dehydration without drinking any water at all as long as they are given food with at least 67% moisture content (7, 9, 10).

Of course, a cat should never be without fresh water, but it goes to show just how important dietary water is to cats. Canned food replicates the water content of prey well and helps keep cats hydrated. This prevents urinary and kidney problems, which are common in cats and can be very dangerous (3, 5, 6, 11). Cats fed dry food will drink more water, but they don’t drink enough to compensate, resulting in dehydration and possibly health problems (6).

Canned food is usually higher in protein and made with more animal ingredients than dry food, although cheap, low-quality canned food may still be more plant-based. Reading labels is important, even though pet food labels are not as informative as human food labels. When doing so, keep in mind that the amounts of nutrients are listed as percentages, so the more moisture a food has, the less of other nutrients it may seem to have. Some math may be required to determine the comparative dry weight nutrient content.

Calico cat drinking from garden pool
Cats need to get most of their water from their food – Photo by Dorothea OLDANI on Unsplash

Canned food isn’t perfect. A positive correlation has been demonstrated in cats between hyperthyroidism and eating canned food (5, 12). The cause of the correlation is unknown, although there are a number of theories, one of which suggests that the actual cause is a fire-retardant chemical present mostly in indoor fabrics, not the food (13). However, until we know more, all that can be said for sure is that a correlation has been found.

Semi-moist food comes in plastic pouches or trays, which often aren’t recyclable, so I have to say it isn’t my preference just because of the environmental impact of all that plastic. However, semi-moist food provides cats with quite a bit more water than dry food while not going bad in the bowl as quickly as wet food, so it can be a good compromise between a cat’s need for dietary water a human’s busy schedule. Semi-moist food tends to feature animal ingredients as the main event, providing more protein and a more species-appropriate dish than many dry foods (1). Those pouches and trays are pre-portioned and easy to dump in the bowl, but do be careful that the portion it comes in is right for your cat if you choose this option.

Because cats are the domesticated version of a desert animal, dietary water is extremely important. If for this reason and no other, canned food, ideally a high-quality, meat-forward one, would be the best option. Not everyone can afford the most expensive, gourmet canned food, however. Cheap canned food or semi-moist food is still a good option. A 2010 study showed that cats exhibited better urinary health if water was simply added to their dry food (11). We all have to figure out the best plan for ourselves and our cats. If your cat has specific dietary needs, and you aren’t sure how that would affect what form of food would be best for them, it’s always a good idea to ask your veterinarian.

Works Cited

  1. Cornell Feline Health Center. (2017, July). Feeding your cat. Cornell University College of Veterinary Medicine. Retrieved here.
  2. Feuer, D. (2006). Your Cat’s Nutritional Needs. National Research Council.
  3. Kelsey, A. (2014). 6 reasons why dry food does not clean your cat’s teeth. Cat Behaviourist. http://www.catbehaviourist.com/blog/6-reasons-dry-food-clean-cats-teeth/
  4. Watson, A.D. (1994). Diet and periodontal disease in dogs and cats. Australian Veterinary Journal, 71(10), 313-318. DOI: 10.1111/j.1751-0813.1994.tb00905.x
  5. Barchas, E. (2017, July 31). Ask a vet: Would you recommend wet food or dry food for cats? Catster. https://www.catster.com/lifestyle/wet-dry-cat-health-canned-food-kibble-cats-ask-a-vet
  6. Pierson, L.A. (2016, November). Feeding your cat: Know the basics of feline nutrition. CatInfo.org. https://catinfo.org/
  7. Case, L.P., et al (1995). Canine and feline nutrition. Mosby, Inc.
  8. Ackerman, N. (Ed.). (2016) Aspinall’s complete textbook of veterinary nursing, 3rd edition. Elsevier.
  9. Prentiss, P.G., Wolf, A.V., Eddy, H.A. (1959). Hydropenia in cat and dog. Ability of the cat to meet its water requirements solely from a diet of fish or meat. American Journal of Physiology, 196(3), 625-632. https://doi.org/10.1152/ajplegacy.1959.196.3.625
  10. Caldwell, G.T. (1931). Studies in water metabolism of the cat. The influence of dehydration on blood concentration, thermoregulation, respiratory exchange, and metabolic-water production. Physiological Zoology, 4(2), 324-359. Retrieved from https://www.jstor.org/stable/30151145
  11. Waltham Petcare Science Institute. (n.d.) Cats benefit from increased dietary moisture. https://www.waltham.com/news-events/nutrition/cats-benefit-from-increased-dietary-moisture/5548/
  12. Edinboro, C.H., et al. (2004). Epidemiologic study of relationships between consumption of commercial canned food and risk of hyperthyroidism in cats. Journal of the American Veterinary Medical Association, 224(6), 879-886. DOI: 10.2460/javma.2004.224.879
  13. Hofve, J. (n.d.) Feline hyperthyroidism. Jackson Galaxy. https://www.jacksongalaxy.com/blog/feline-hyperthyroidism/

Published July 12th, 2020

Updated November 21st, 2020

Cat Care

In Search of the Best Cat Food, Part I: Feline Nutrition

mehshadoweye

Meredith Hemphill

mehshadoweye

Encyclopaedia Felidae now has a Patreon! Go to www.patreon.com/EncyclopaediaFelidae if you want to help support this content!

Brown tabby eating out of bowl
Photo by Hans Reniers on Unsplash

Today I am trying something new on this blog. Almost anyone with a pet has asked the question, “What is the best food to give them?” Even after asking the advice of my veterinarian what to feed my cat, I still felt pretty lost and confused. I am undertaking a series of articles in which I aim to gather as much information as I can about feline nutrition and what difference the many kinds of cat food really make on a cat’s well-being.

The series will have five parts: feline nutrition, wet vs. dry food, diets for different life stages, specialty diets, and indoor diets. I will be interspersing other articles during this series so that it doesn’t get boring. Feel free to comment with your own questions about cat food, and I will look into them.

Of Carnivores and Calories

To begin with, I thought it would be helpful to go over the basic facts of feline nutrition. The fundamental elements of an animal’s diet, humans included, are very simply broken down into protein, fat, carbohydrates, vitamins, and minerals. Cats of all kinds are obligate carnivores. That means that they have evolved to eat only meat, and they are not well-equipped to derive nutrition from plant sources. This has a major impact on their nutritional needs.

The amount of calories a cat needs per day depends upon their age, activity level, health, and whether or not they have been sterilized. Growing kittens and pregnant or nursing queens need significantly more energy. Intact adults need a bit more than neutered adults. An eight-pound adult cat needs about 240 kcal (kilocalories, or what we usually just call calories) each day [1]. The Animal Medical Center of Chicago has a very helpful chart for getting a good idea of how many calories your cat or kitten is likely to need, which you can download a copy of below [2]. Because cats have evolved to eat only meat, their bodies are designed to obtain these calories primarily, if not exclusively, from proteins and fats.

Calorie Requirements For CatsDownload

Macronutrients in Feline Nutrition

Carbohydrates and Proteins

Obligate carnivores require a high protein, moderate fat, low carbohydrate diet to be their healthiest. Carbohydrates, which are plentiful in plant matter, can be difficult for cats to digest and are not necessary in the feline diet [3]. Instead of deriving most of their energy from carbohydrates, as humans do, cats use protein as their primary source of energy [4, 5]. A nine-pound cat with a 250 kcal-per-day diet is recommended to receive 12.5 grams of protein each day [3]. It isn’t just the amount of protein that matters, however. Proteins are made of molecules called amino acids. There are 23 amino acids. Cats can manufacture some of these themselves, but there are 11 that they must get from their diet [6, 7]. These are known as essential amino acids. The essential amino acids for cats are:

Black and white cat watching mouse
Some cats are fiercer hunters than others, but all are obligate carnivores – Image by Erika Stockenhofen from Pixabay
  • Arginine
  • Histidine
  • Isoleucine
  • Leucine
  • Lysine
  • Methionine
  • Phenylalanine
  • Taurine
  • Threonine
  • Tryptophan
  • Valine

Taurine is an unusual requirement particular to cats, but it is very important. A taurine deficiency can lead to blindness, deafness, heart problems, and loss of kittens or congenital defects with pregnant queens [3, 7]. Taurine is only present in animal protein, a callback to the nature of cats as obligate carnivores [7].

Fats

Cats also have rather specific needs when it comes to the fats in their diets. We have a tendency to think of fat as a dirty word, but fats serve very important functions in the body, in appropriate quantities. Fats are an important source of energy, they provide insulation to nerve fibers and protection to internal organs, they aid in absorption of the fat soluble vitamins, and they are critical for cell structure and function [3, 6, 7]. Cats can tolerate fairly high amounts of dietary fat since it is such an important energy source for them [3]. The average cat we used as an example before has a recommended daily allowance of 5.5 grams of fat [3].

Fats are composed of fatty acids, and like amino acids, some of these can be made in the body, and some cannot. Science is still learning which fatty acids are essential for cats, but some things are well-known. Cats are unable to manufacture arachidonic acid, an important precursor molecule with end products that have wide range of functions in the body [6]. Arachidonic acid is found only in animal fat [7]. Linoleic acid is an essential fatty acid for all animals [7]. DHA is a fatty acid that has been shown to be important for the neural development of kittens, so it may be necessary for reproducing queens and young, weaned kittens [6, 7].

Micronutrients in Feline Nutrition

Now, let’s talk micronutrients. Vitamins are organic nutrients, manufactured by a lifeform somewhere in the food chain. Minerals are inorganic nutrients that come from the environment. Cats need Vitamins A, D, E, K, and the B complex [3, 6, 7]. They have no need for dietary Vitamin C, as they are able to make that for themselves [6, 7]. Minerals are a bit trickier, since some of them are needed in very small amounts but are still absolutely critical. The US National Research Council considers twelve minerals essential for cats [3], but I included a thirteenth from another source as well [6].

Vitamins

Five eggs
Photo by 青 晨 on Unsplash

Vitamin A is a big one for cats. Some animals can make Vitamin A from precursors in plants, like beta-carotene, but cats can’t do that [7, 8]. They have to consume Vitamin A in its completed form from animal sources [7, 8]. Vitamin A is important for vision–especially night vision, healthy skin and mucous membranes, and normal bone and tooth growth [6, 7]. Fish oil, liver, eggs, and dairy are natural sources of Vitamin A [6, 7].

Vitamin D is needed for the body to use calcium and phosphorous [6, 7]. Cats can synthesize it in their skin in the presence of UV light, but not very well, so dietary Vitamin D is important [6]. It can be found in marine fish and fish oils, liver, and egg yolks [6, 7]. Vitamin E is an antioxidant synthesized by plants but present in small amounts in animal sources [6]. The amount a cat needs depends upon how much oxidative stress their body is under [6, 7]. Vitamin K is important for blood clotting, but healthy cats are able to synthesize enough of it on their own [6, 7]. If the intestinal bacteria that normally make Vitamin K are decreased, perhaps if the pet is on antibiotics, dietary Vitamin K can become important [6]. In that case, fish meal, egg, and liver can be good sources [6].

There are eight B vitamins, which are necessary for energy metabolism and making healthy tissues [6]. Because they are soluble in water, it is uncommon for a cat to get too much of a B vitamin. The excess just washes out in the urine [7]. Cats usually get enough B vitamins from their food, but while most animals can synthesize niacin, or B3, cats can’t and must get it from their diet [6]. Fortunately, meat is a good source of niacin [6]. The other B vitamins can come from eggs, organ meats, or muscle meat, depending on the B vitamin in question [6].

Minerals

Salmon steak
Salmon is a good, species-appropriate source of potassium – Image by congerdesign from Pixabay

We have a bunch of minerals to get through, and I would feel like I wasn’t providing the most complete information if I left any out. But I don’t think anyone wants this article to go on for twenty pages, so I’m going to summarize the main reasons each mineral is important and where cats get the minerals from in their diet [3, 6, 7].

  • Calcium for skeletal and muscular health: poultry/meat meals, bone
  • Phosphorous for skeletal health and energy metabolism: meat, poultry, fish
  • Magnesium for muscle, nerve, and hormone function: bone meal
  • Sodium for homeostasis and nerve function: fish, poultry meal, eggs
  • Potassium for nerve and enzyme function: fish, especially salmon [9]
  • Chloride for homeostasis: fish, poultry meal, eggs
  • Iron for red blood cells and energy metabolism: meat, organ meat
  • Copper for tissue synthesis: organ meat
  • Zinc for cell growth and wound healing: beef liver, dark poultry meat, egg yolks
  • Manganese for bone growth and neurological health: meat, poultry, fish
  • Selenium for antioxidant activity and immune health: meat, poultry
  • Iodine for thyroid function: meat, poultry
  • Sulfur for protein synthesis: meat, poultry, fish

Moving Forward

What do we do with this information? Out of curiosity, I grabbed one of Joon’s cat food cans to see how much of this information is actually available on the label. What I found was a section giving the crude protein, crude fat, crude fiber, moisture, “ash,” calcium, phosphorous, magnesium, and taurine content in either minimum or maximum percentages. Ash is a term sometimes used to refer to mineral content [6]. Below that, the kcal per can and per kilogram (of this food that comes in 170-gram cans) was given. That gives me the ability to calculate the gram values of the nutrients, although it’s frustrating that I have to. And then there’s the brief feeding instructions, with the ingredients on another panel.

It’s less information than I would have hoped for, and it’s presented much less plainly than on human food labels here in the US. So I tried one of the cans of prescription food we give my parents’ elderly cat. I thought maybe it was just the company I buy Joon’s food from. Nope, Rosie’s food had even less information on it. There were no percentages for minerals at all.

As we continue with this series, I’ll delve into different types of food and what it all means. What looking at the back of this can is telling me right now, however, is that as pet parents we need to be as informed as we can. Evidently, no one is going to hand the information we need about feline nutrition to us. At least, not anybody in the pet food aisle. If I look at the ingredients, I can see that this food has a lot of added nutrients and ingredients that provide them naturally, but a few hours ago I wouldn’t have known that including tuna and fish oil in a chicken-flavored food can provide nutrients that the chicken alone might not. The more we know, the better prepared we are to make the best decisions possible for our cats.

Works Cited

  1. How many calories should your dog or cat eat daily? (2014, April 25). Dunloggin Veterinary Hospital. https://dunlogginvet.com/how-many-calories-should-your-dog-or-cat-eat-daily/
  2. Calorie Requirements for Cats (n.d.). Animal Medical Center of Chicago. https://www.animalmedicalcenterofchicago.com/cat-diet-calorie-requirements-for-cats/
  3. Feuer, D. (2006). Your Cat’s Nutritional Needs. National Research Council.
  4. Optimum feline nutrition: what should you feed your cat? And feline weight loss and prevention plan. (n.d.). Cat Care Center of Baton Rouge. https://www.catcarecenter.com/services/cats/feline-nutrition-cat-food
  5. Llera, R. and Ward, E. (2019). Nutrition: General feeding guidelines for cats. VCA Hospitals. https://vcahospitals.com/know-your-pet/nutrition-feeding-guidelines-for-cats
  6. Case, L.P., et al (1995). Canine and feline nutrition. Mosby, Inc.
  7. Ackerman, N. (Ed.). (2016) Aspinall’s complete textbook of veterinary nursing, 3rd edition. Elsevier.
  8. Schultze, K.R. (2010, February 9). Your cat’s nutritional needs: The basics. Feline Nutrition Foundation. https://feline-nutrition.org/nutrition/your-cats-nutritional-needs-the-basics
  9. Millen, B. et al (2015). Appendix 10: Food sources of potassium. Health.gov. https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/appendix-10/

Published July 5, 2020

Updated June 20, 2022