genetics Archives • Encyclopaedia Felidae

Meredith Hemphill

mehshadoweye

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A couple days ago, my friend texted me while they were looking at a black panther exhibit at the art museum and asked me what kind of cat black panthers actually are. I had to break it to them–and now to you–that there really isn’t any such thing as a black panther. The name “black panther” is applied to individuals of several species of wild cat which are all black due to a rare genetic condition called melanism. Most black panthers are actually leopards or jaguars, both of which are normally yellow with black spots [9].

What is melanism?

Graphic showing which felids can be melanistic — Many cats come in black [4]

Melanism is a rare genetic mutation that causes animals to have black skin and fur/feathers/whatever when members of their species typically do not [1, 3, 4, 7, 9]. The mutation causes the affected animals to produce an excess of the dark color pigment melanin [1, 2, 7]. Lots of animals can be melanistic, including pigs, cows, mice, butterflies, snakes, lizards, and snails [2, 4, 7]. Melanism is more common in felids than most taxa, however [1-3, 7]. 15 of the 40 species in the genus Felidae are known to exhibit melanism [4].

Melanistic cats have black fur all over their bodies but may still have some of the patterning or their “normal,” or wild-type, brethren. For example, black leopards still have rosettes which are even darker black [7, 9], and some melanistic Asian golden cats have a white mark on the underside of their tails [4].

Melanism mutations have cropped up at least eight separate times in the cat family tree [3]. These different mutations don’t all work exactly the same way. Mutations in the ASIP gene are recessive, meaning that a cat has to inherit the mutation from both parents to be black [2, 7]. The ASIP protein normally inhibits eumelanin (dark pigment) production, and these mutations make the ASIP protein non-functional [2, 7]. Leopards and Asian golden cats inherit melanism as a recessive ASIP mutation [2, 3, 6-9].

Mutations in the MC1R gene are dominant, so a cat can inherit either one or two copies of the mutation to be melanistic [2, 7]. MC1R promotes the production of eumelanin, and the mutations increase its activity [2, 7]. Jaguars and jaguarundis inherit melanism as a dominant MC1R mutation [2, 9].

How many black panthers are there?

In general, the rate of melanism in the felid species that have it is thought to be around 10% [3, 9]. However, the actual percentage varies widely depending upon the species and specific population [1, 3, 4, 8]. Leopards range throughout Africa, up through Asia, and as far north as Siberia. In Africa, they are almost never seen in their black panther form, but in Malaysia, the exact opposite is true–almost all leopards are black [3, 4, 7-9]. Southeast Asia in general has about half melanistic, half wild-type leopards [3]. Servals are more likely to exhibit melanism in the East African highlands and the Tsavo ecosystem of southeast Kenya [1]. While most species have fewer melanistic cats than wild-type, 80% of jaguarundis are melanistic [2, 4].

Melanistic (A) and wild-type (B) tigrinas [4]

It’s difficult to get an accurate count of how many wild cats there are in the world to begin with, due to their stealth and dwindling habitats. Counting black cats has its own particular challenges. Sometimes reports of a “black panther” are ambiguous or a case of mistaken identity [5]. There is still debate about whether or not melanistic cougars actually exist for that reason [5]. Because melanistic wild cats are rare in most environments, people are more likely to take notice of them and tell somebody if they see one, possibly inflating their numbers [1].

Why are only some big cats melanistic?

The evolution of melanism in felids is still up for discussion among biologists. The most prominent theory is that melanism is so common among cat species because it helps camouflage them in dark, forested places [3, 8]. As ambush predators–and sometimes prey for bigger animals–most cats specialize in stealth, so camouflage is important. This would explain why melanism is more common in cats in jungle habitats and very rare in open grasslands where a black cat would really stand out [3, 8].

Researchers have found some other possible benefits to being a black panther, too. Dark coloration may aid in temperature control in high-altitude or cool, moist forest environments [1, 9]. Research in dark-colored birds has shown that they are resistant to feather-degrading bacteria [3], so there is a possibility that melanistic felids have some additional immunity to disease [3, 8].

There may be some downsides to that glossy black coat, however, even in favorable habitats. Black leopard pairs have smaller litter sizes [6], although the melanism mutation itself appears to have no ill effects [7]. Graipel et al. found evidence that melanistic cats in some species may have a disadvantage in communicating with their peers because the lack the white spots behind their ears or on their tails characteristic of their species [4]. Wild cats use these spots to send signals to each other at short distances, silently, without alerting prey or predators [4]. This is more important for some species than others, depending upon their habitat and whether they are more active when it’s light or dark [4]. Some felids don’t have these spots at all [4]. So it’s more advantageous to dress in black for some cats than for others.

Miniature black panthers

One of the felid species that exhibits melanism is the domestic cat, Felis catus [7]. That’s right, you might have a black panther of your very own! Not all black housecats are melanistic, however, because coat color genetics are complicated. Melanistic cats will be solid black, absolutely no white hairs, and their skin will be black as well. Also, fun fact: melanistic kittens often have “ghost” tabby stripes that typically fade with time, like the black leopard’s shadowy spots [7].

Sources

Adkins, B. (2019, May 12). Melanism in servals. Sheldrick Wildlife Trust. https://www.sheldrickwildlifetrust.org/news/wilderness/melanism-in-servals
Eizirik, E., Yuhki, N., Johnson, W. E., Menotti-Raymond, M., et al. (2003). Molecular genetics and evolution of melanism in the cat family. Current Biology, 13(5), 448-453. https://doi.org/10.1016/S0960-9822(03)00128-3
da Silva, L. G., Kawanishi, K., Henschel, P., Kittle, A., et al. (2017). Mapping black panthers: Macroecological modeling of melanism in leopards (Panthera pardus). PLoS One, 12(4), e0170378. doi:10.1371/journal.pone.0170378
Graipel, M. E., Bogoni, J. A., Giehl, E. L. H., Cerezer, F. O., et al. (2019). Melanism evolution in the cat family is influenced by intraspecific communication under low visibility. PLoS One, 14(12), e0226136. https://doi.org/10.1371/journal.pone.0226136
Hartwell, S. (n.d.). Mutant pumas. Messybeast. http://messybeast.com/genetics/mutant-pumas.html
Robinson, R. (1970). Inheritance of the black form of the leopard Panthera pardus. Genetica, 41, 190-197. https://link.springer.com/article/10.1007/BF00958904 [Abstract]
Schneider, A., David, V. A., Johnson, W. E., O’Brien, S. J., et al. (2012). How the leopard hides its spots: ASIP mutations and melanism in wild cats. PLoS One, 7(12), e50386. doi:10.1371/journal.pone.0050386
Sunquist, F. (2006, December 1). Malaysian mystery. The National Wildlife Federation. https://www.nwf.org/en/Magazines/National-Wildlife/2007/Malasian-Mystery
Zaccaria, J. (2019, October 28). Wild cats 101: Black cats and more on melanism. Panthera. https://panthera.org/blog-post/wild-cats-101-black-cats-and-more-melanism

Published October 8th, 2023

Science

Gene therapy may hold promise for cat birth control

July 9, 2023July 4, 2023 mehshadoweye

Meredith Hemphill

mehshadoweye

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

Tabby cat carry her kitten — Image by Rajesh Balouria from Pixabay

Last month, an article was published in Nature Communications by a team of scientists from the Cincinnati Zoo and Botanical Garden, the Horae Gene Therapy Center, and Massachusetts General Hospital [7-9]. They tested a gene therapy injection as an alternative to spaying and neutering for cat birth control, and the results are exciting.

Why do we need cat birth control?

80% of the estimated 600 million domestic cats in the world are strays or feral [4, 9]. Cat overpopulation leads to more disease and greater loss of birds and other small animals from predation [2-6]. Animal shelters become overrun with homeless kittens and cats, and many are ultimately killed. Cats reproduce very quickly, so it doesn’t take long for a few to become a serious overpopulation issue. The only method of sterilization currently available is spay/neuter surgery. It is effective and permanent, but there are drawbacks.

Surgical sterilization has to be performed by a veterinarian at a surgical clinic [2]. It’s an invasive procedure for females, and both sexes are supposed to have a recovery period, including medication [2]. It’s also expensive [2, 6]. Those resources are in short supply, even more so in developing countries [1, 2, 6]. Thus, there has been interest in non-surgical cat contraception for years. Previous attempts have included vaccines targeting the pituitary gland, toxins targeting reproductive cells, and RNA-silencing drugs to shut down the genetic mechanism of conception [1, 3, 5]. All were either ineffective or unsafe [3, 5].

The Alliance for Contraception in Cats and Dogs (ACC&D) was founded in 2000 with the goal of finding a one-time, permanent, non-surgical contraceptive that would help to curb the overpopulation of homeless cats and dogs [1, 5]. ACC&D wasn’t involved in this study, but ACC&D President Joyce Briggs said, “This research is a huge leap—we’re really excited about it” [1, 5]. She also noted that the lead author, Dr. Lindsey Vansandt, is someone they have worked with before on a contraceptive vaccine called GonaCon [1].

The organization that provided the primary funding for the Vansandt research team has a similar goal. The Michelson Found Animals Foundation was founded in 2009 by inventor Gary Michelson [1, 2, 5]. Its goal is also a single-use, permanent, non-surgical dog and cat birth control, although specifically as a marketable product [1, 2]. Toward this end, the Michelson Found Animals Foundation created the Michelson Prize, $50 million (USD) in research funding plus $25 million if successful [1, 2, 5, 7]. So far, they have given out 41 grants [1, 5].

David Grimm, a journalist for Science, explained that it can be very difficult to get funding for this kind of research; most of the money goes toward studying the human body. So the Michelson Prize grants have been a huge boost to searching for a better companion animal contraceptive. [2]

The Experiment

Dr. David Pepin didn’t have his eyes on the Michelson Prize at first, however. Pepin was looking for ways to help women with ovarian cancer preserve their fertility [6-8]. He was studying anti-Müllerian hormone (AMH), sometimes called Müllerian inhibiting hormone (MIS), which made by the ovarian follicles of female mammals [1, 2, 4-8]. An ovarian follicle is a layer of cells around an egg that nourish the egg as it grows and matures.

Pepin was trying to learn more about what AMH does, so he injected an extra copy of the AMH gene into female mice [2, 4, 5]. This technique, sometimes called gene therapy, does not change the native DNA. It adds new, free-floating pieces of DNA into the cells, complete with all the information the cells need to read the “instructions” on the new piece of DNA. Gene therapy has been used to treat genetic diseases in humans, hence the name, but in this case Pepin was using the same procedure for research purposes to see how the mice would respond to high levels of AMH. He was surprised when the mice’s ovaries shrank, stopped producing eggs, and became infertile [1, 2, 4-6].

“We thought, well, this is a very interesting tool, but what can we use it for?” Pepin said [4]. He decided to submit an application for a Michelson Prize grant, and Bill Swanson, Director of Animal Research at the Cincinnati Zoo, happened to review it [1, 2, 4, 5]. Swanson had actually been working on an opposite project, trying to increase breeding in captive big cats [2, 5]. However, the Cincinnati Zoo maintains a research colony of domestic cats, and Swanson thought Pepin’s proposal was a great idea, so a partnership was struck [2, 4, 5].

Diagram of cat birth control experiment — Experimental design – From Vansandt et al. 2023

The study was small, with three groups of only three she-cats each [3-5, 7, 9]. The nine cats were all named after former first ladies: Michelle, Betty, Abigail, Nancy, Dolly, Barbara, Rosalyn, Jacque and Mary [4]. The domestic cat gene for AMH was constructed into a piece of DNA that the cats’ cells could read, and then that piece of DNA, named fcMISv2, was taken up by the harmless AAV9 virus [9]. Viruses are used in gene therapy because they naturally have the ability to insert genetic material into cells. Three cats served as a control group and were injected in the thigh muscle with AAV9 viruses that were empty, no DNA to inject [3, 7, 9]. Three cats were injected with a lower dose of viruses carrying the gene, and the other three received a higher dose [3, 7-9].

The experimental cats’ muscle cells successfully incorporated the fcMISv2 DNA and began to make AMH [9]. According to Pepin, “A single injection of the gene therapy vector causes the cat’s muscles to produce AMH, which is normally only produced in the ovaries, and raises the overall level of AMH about 100 times higher than normal” [7, 8]. Although their AMH levels increased, only progesterone decreased in response [5, 9]. Their other hormone levels remained the same, their hormone cycles were unaffected, and they showed no signs of adverse side effects [2, 3, 5, 7-9].

During two mating trials, two different toms were each introduced to the nine she-cats for four months at a time [3, 5, 7, 9]. All of the cats in the control group mated, became pregnant, and gave birth to kittens [3, 5, 7-9]. Only two of the cats who received gene therapy even allowed the toms to mate, and none of them ever became pregnant or had kittens [3, 5-9]. At the end of the two-year study, they were maintaining steady, elevated AMH levels, and the scientists are cautiously optimistic that this method may be a permanent contraceptive [5, 7-9].

What happens next?

It remains unclear exactly how AMH functions as kitty birth control [1, 2, 5, 9]. The researchers believe that the elevated levels of AMH prevent she-cats’ follicles from developing and thereby prevent ovulation [2-5, 9]. However, more research is needed to understand exactly how AMH works, and to answer lingering questions.

For instance, is this sterilization truly permanent [1, 2, 6]? The scientists who authored the study believe it is, but they only tested those cats for two years, so no one can say for sure yet that it doesn’t eventually wear off. Are there any negative side effects that they didn’t catch in such a small study [6]? Could AMH work for dogs, too [1, 2, 5, 6]? That is an important goal of this kind of research, not to mention a requirement to win the Michelson Prize [1, 5]. There are also concerns about cost, as that is often what prevents people from spaying and neutering cats now [1, 2]. If a new AMH shot will cost as much or more than surgically sterilizing cats, the convenience of the one-dose injection won’t really matter [1, 2].

Pepin, Swanson, and the Michelson Foundation are already in talks with the Food and Drug Administration about a larger trial and the possibility of bringing an AMH drug to market [2, 5, 6], so keep your ear to the ground. In the meantime, GonaCon, the cat birth control vaccine that study author Lindsey Vansandt worked on with ACC&D, has shown promise as well and may actually be closer to becoming available [1]. Either way, this area of study appears to be accelerating, and there may be more exciting news to come in the next few years.

Two kittens peeking through hole in wooden wall — Effective feline contraception means fewer homeless kittens – Image by Sommer from Pixabay

As for the cats from the study, they were all put up for adoption after the research concluded [4]. This is something the Cincinnati Zoo does with their research participants–Bill Swanson already has three cats he adopted from previous studies [4]. I couldn’t find out if all nine have been adopted yet, so if you live in the Cincinnati area and are looking for a new feline friend, email [email protected]. The cats’ new owners are asked to bring them back to the zoo for a yearly check-up to monitor their hormone levels and make sure there haven’t been any side effects [4].

References

Clifton, Merritt. (2023, June 8). No, the wait for a single-shot chemosterilant for cats has not ended. Animals 24-7. https://www.animals24-7.org/2023/06/08/no-the-wait-for-a-single-shot-chemosterilant-for-cats-has-not-ended/
Crespi, S. (Producer). (2023, June 8). Contraception for cats, and taking solvents out of chemistry [Audio podcast episode]. In Science Podcast. American Association for the Advancement of Science. https://www.science.org/content/podcast/contraception-cats-and-taking-solvents-out-chemistry
de Jesús, E. G. (2023, June 6). A gene therapy shot might keep cats from getting pregnant without being spayed. ScienceNews. https://www.sciencenews.org/article/gene-therapy-shot-cats-spay-pregnant
Golembiewski, K. (2023, June 6). Nonsurgical cat contraception could help curb overpopulation, study says. CNN. https://www.cnn.com/2023/06/06/world/cat-contraceptives-scn/index.html
Grimm, D. (2023, June 6). Hello kitty, goodbye kittens? Gene therapy spays cats without surgery. Science. doi: 10.1126/science.adj0979
Katsnelson, A. (2023, June 6). Gene therapy may offer birth control for cats. The New York Times. https://www.nytimes.com/2023/06/06/science/cats-birth-control.html
Ridings, M. (2023, June 6). Birth control for cats? Harvard Gazette. https://news.harvard.edu/gazette/story/2023/06/birth-control-for-cats-is-effective-but-ahead-of-its-time/
Today’s Veterinary Business. (2023, June 19). Gene therapy shows promise in feline contraception. https://todaysveterinarybusiness.com/gene-therapy-0623/
Vansandt, L. M., Meinsohn, M., Godin, P., Nagykery, N., et al. (2023). Durable contraception in the female domestic cat using viral-vectored delivery of a feline anti-Müllerian hormone transgene. Nature Communications, 14, 3140. https://doi.org/10.1038/s41467-023-38721-0

Published July 9th, 2023

Breed Profiles

Ragdoll: The Most Laidback Cat You’ll Ever Meet

September 11, 2022June 14, 2023 mehshadoweye

Meredith Hemphill

mehshadoweye

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

Bicolor Ragdoll cat on blue velvet — Lilac Bicolor Ragdoll – Image by 孟想家 from Pixabay

One of the biggest, fluffiest cats is also the cuddliest and most relaxed. The Ragdoll is an easy-going snuggle bug known for going limp like a ragdoll when held. They are a consistently popular breed, despite being quite expensive and new to the cat fancy [4, 12]. Let’s meet these friendly giants.

The Cat from Space?

The Ragdoll’s origins are fairly mundane, although there are some creative conspiracy theories about them. A woman named Ann Baker developed the breed in Riverside, California in the early 1960s [4-9, 11, 12]. Baker began with a long-haired, white stray she-cat she found in her neighborhood and named Josephine [5-9, 11, 12]. Baker added other domestic longhairs that she owned or found to the breeding program, selecting for gentle temperaments, large size, and long colorpoint coats [4-8]. She recruited other breeders to help expand her new breed [1, 4, 11]. Persians, Birmans, and Burmese may have been added to the program [7, 8].

Ann Baker named her creation the Ragdoll for their tendency to relax limply when picked up [6, 7, 12]. However, she had increasingly eccentric ideas about why the cats behave this way. She claimed that Josephine only had “normal” kittens until she was hit by a car and had to be taken to a veterinary center where Baker said Josephine’s genes were altered [4, 11]. All the litters she bore afterwards, allegedly, had the Ragdoll temperament. The stories only got stranger, incorporating space alien involvement, CIA experiments, and human-to-cat gene splicing [2, 6].

We can’t say why Ann Baker said those things, or if she truly believed them. It is public knowledge that the other Ragdoll breeders she had recruited started to distance themselves from her and developed the breed to show quality without her [4, 6, 11].

Breed Characteristics

Appearance and Patterning

Ragdolls are big kitties, weighing 10-20 pounds (4.5-9 kg) with females typically smaller than males [4-9, 11]. Ragdolls have long, heavy-boned bodies [1, 6, 11]. Their paws are tufted, and their tails are plumed [6]. Ragdolls all have blue eyes [1, 4-9, 11]. Their fur is semi-long, soft, and silky [4-7, 9, 11]. The fur is longest on their necks, creating a ruff [1, 6, 9].

Ragdoll cats come in four coat patterns: colorpoint, mitted, bicolor, and van [1, 4-8, 11, 12]. They can be any color and can also be lynx (tabby), tortoiseshell, or both [4-6, 8, 11, 12]. Colorpoint cats are darkest on their face, feet, tail, and ears. Mitted Ragdolls have a colorpoint pattern except their paws are white, giving the appearance that they’re wearing white mittens [1, 4-8, 11, 12]. Bicolors are white on all four paws, underbelly, chest, and an inverted V on their face [1, 4-6, 7, 11, 12]. Vans are mostly white with full color only on the ears, tail, top of the face mask, and sometimes scattered on the body [5, 12]. Not all cat associations recognize the Van pattern.

Personality

Ragdolls are very people-oriented and affectionate [4-6, 8, 11, 12]. They love to cuddle and spend time with their humans [4, 6, 8, 9, 11]. They are famously gentle and docile [2, 5-7, 11]. Though they’re reputation for flopping about like a plush toy may make them seem lazy, they actually aren’t. While it’s true that Ragdolls are not an active breed per se, they are quite playful [6, 11]. Some even enjoy learning tricks and games like fetch [4-6, 11, 12].

Ragdolls tend to be “floor cats,” in the words of the Cat Fanciers’ Association [4, 5]. They usually prefer being on or near the ground and aren’t much for climbing, high jumps, and feats of aerial acrobatics [4, 5, 6, 12]. That doesn’t mean they don’t need any space to themselves, though! It just means a Ragdoll will usually prefer something shorter like a scratching post or hideaway box.

Ragdoll Myths

Seal point Ragdoll cat on tile floor — Seal Mitted Ragdoll – Image by atrix9 from Pixabay

1. Ragdolls are hypoallergenic.

Because their pelt lacks an undercoat, Ragdolls don’t shed as much as most cats [4-6, 9]. Because of this, there is a myth that they are hypoallergenic. However, it is cats’ saliva and dander that cause allergic reactions in people with cat allergies [9]. Less shedding may mean those allergens aren’t spread around the house quite so much, so some allergy sufferers might find Ragdolls easier to be around [9]. But there’s no guarantee. Therefore Ragdolls are not considered a hypoallergenic breed [4, 9].

2. All Ragdolls go limp every time you pick them up.

The breed’s name ensures that it’s reputation precedes it. Many people are under the impression that there is a special Ragdoll mutation affecting the nervous system that causes the Ragdoll flop [2]. However, the truth is that Ragdolls were simply bred to be so relaxed and friendly that they just melt when given affection [2]. Not all of these cats will ragdoll like that, though [2]. Every cat is an individual, and every interaction is unique.

3. Ragdolls do not feel pain.

This is an odd but persistent myth that reportedly goes all the way back to Josephine. The theory goes that because she gave birth to the first Ragdoll kittens after being hit by a car, the kittens and their descendants do not feel pain [1]. Medically, that is ridiculous. I suspect the docile and tolerant temperament of the cats made people think they were insensitive to pain, and people made up a reason why that would be the case. This is completely false, however. Ragdolls may be willing to put up with a lot, but they feel pain and discomfort just as much as any other cat [1, 12].

Living with Ragdolls

Ragdolls are considered a low-maintenance breed. Their fur isn’t prone to matting, thus requires only regular combing [4-7, 9, 11, 12]. The lack of undercoat can cause some Ragdolls to build up grease in their fur, so they need occasional baths [4, 6]. There are professionals who do that if you’re feeling intimidated.

This is a breed that gets along with everybody. They love people, are patient with children, and get along with other animals, including dogs [4, 6, 9, 11, 12]. In short, Ragdolls are great family pets. Because they are calm, cuddly, and not super active, they can be good pets for seniors who need some company [4]. They are soft-spoken cats and not very talkative [6, 8]. This can make them a good option for apartment living where a loud cat might bother the neighbors [8].

Ragdolls do need a lot of attention and are prone to loneliness [4]. If you want an independent cat that won’t mind being left home alone a lot, this is not the breed for you. A Ragdoll is likely to meet you at the door, follow you around, and try to participate in everything you are doing [4, 5, 6, 8, 12]. They just want to be your best friend.

Health Concerns

Ragdolls are pretty healthy cats, probably due to their origins among random-bred cats, but there are a few problems they have a genetic predisposition to. Like other large breeds, they are prone to obesity, so their food intake needs to be monitored carefully [9]. They also have an elevated risk of developing Feline Infectious Peritonitis [6].

Ragdoll cats have a predisposition to urinary tract problems, especially bladder stones [4, 6, 9]. Making sure your Ragdoll stays well-hydrated is important for prevention [9]. Finally, Ragdolls have a unique risk for hypertrophic cardiomyopathy, the most common form of heart disease in cats [3, 4, 6, 9, 10]. There is a mutation of the myosin binding protein C3 gene prevalent only in the Ragdoll breed that makes them more likely to develop HCM [3, 10]. Cats with two copies of the mutation are at much greater risk [3]. Fortunately, there is now a genetic test for this mutation, called MYBPC3 R820W, that enables breeders to choose not to breed cats that carry it [3, 6, 9, 10].

If you are considering bringing a Ragdoll into your home, remember that even purebred cats end up in shelters and rescues. Look first at breed-specific rescues such as Ragdoll Rescue USA or Merlin’s Hope Ragdoll Rescue in Texas, as well as your local shelter.

Fun Facts

One name considered for the breed early on was Cherubim. [7]
Ragdoll cats are slow to mature. They take 4 years to finish growing! [1, 5, 6, 11, 12]
A Ragdoll named Frank and Louie was the longest-living Janus cat, or two-faced cat. Despite his rare congenital deformity, Frank and Louie lived to be 15 years old. [8]

Frank and Louie

Works Cited

Alderton, D. (1992). Cats: The visual guide to more than 250 types of cats from around the world. Dorling Kindersley: London.
Becker, M. & Spadafori, G. (2006). Do cats always land on their feet? 101 of the most perplexing questions answered about feline unfathomables, medical mysteries, & befuddling behaviors. Health Communications, Inc.: Deerfield Beach, FL.
Borgeat, K., Casamian-Sorrosal, D., Helps, C., Fuentes, V. L., et al. (2014). Association of the myosin binding protein C3 mutation (MYBPC3 R820W) with cardiac death in a survey of 236 Ragdoll cats. Journal of Veterinary Cardiology, 16(2), 73-80. https://doi.org/10.1016/j.jvc.2014.03.005
Braaksma, H. & Guthrie, C. (2022, July 13). Ragdoll. DailyPaws. https://www.dailypaws.com/cats-kittens/cat-breeds/ragdoll
Cat Fanciers’ Association. (n.d.). About the Ragdoll. https://cfa.org/ragdoll/
Cattime. (n.d.). Ragdoll cats. https://cattime.com/cat-breeds/ragdoll-cats#/slide/1
Edwards, A. (2006). The ultimate encyclopedia of cat, cat breeds, and cat care. Hermes House: London.
Fawcett, K. (2022, May 5). 7 facts about Ragdoll cats. Mental Floss. https://www.mentalfloss.com/article/78233/8-friendly-facts-about-ragdoll-cats
Fratt, K. (2022, June 27). Ragdoll cat: Breed profile, characteristics, and care. The Spruce Pets. https://www.thesprucepets.com/ragdoll-cat-breed-profile-4583144
Meurs, K. M., Norgard, M. M., Ederer, M. M., Hendrix, K. P., et al. (2007). A substitution mutation in the myosin binding protein C gene in ragdoll hypertrophic cardiomyopathy. Genetics, 90(2), 61-264. https://doi.org/10.1016/j.ygeno.2007.04.007
The International Cat Association. (2018, August 13). Ragdoll breed. https://tica.org/breeds/browse-all-breeds?view=article&id=868:ragdoll-breed&catid=79
Thornton, K. C. (2018, January 16). The Ragdoll cat: All about this fascinating cat breed. Catster. https://www.catster.com/cats-101/about-the-ragdoll-cat

Published September 11th, 2022

Updated June 14th, 2023

Breed Profiles

Munchkin: The Pint-Sized Kangaroo Cat

July 11, 2021May 12, 2023 mehshadoweye

Meredith Hemphill

mehshadoweye

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

Most people have seen a dog with stubby legs before. Dachshunds, Corgis, Bulldogs, etc. are all familiar sights. But did you know that there are short-legged cats, too? Meet the Munchkin. No one told them they’re too short to ride. These furry racecars are very new to the cat fancy, but they made a big splash from the very beginning. It wasn’t exclusively in a positive way. What’s the big deal with these little cats? Let’s start at the beginning.

Journey to Munchkinland

No one knows exactly when the first short-legged cat was born. They may have been around for the entire history of domestic cats. The first time they were described, however, was 1944, in England (2, 6, 7, 9, 10). Veterinarian Dr. H. E. Williams-Jones recorded four generations of short-legged cats (2, 7, 10). Interestingly, this feline family had short forelegs but normal-length hind legs (2, 9, 10). Like many other pedigrees, these so-called Kangaroo Cats went extinct during World War II (2, 5, 7, 10).

Old photo of tabby and white Munchkin — Australian she-cat with short forelegs, late 1800s/early 1900s. Possibly 1st documented short-legged cat. – Image from Messy Beast

Short-legged cats were spotted in various locations throughout the twentieth century, however (2, 5-7, 10). Sometimes they would have four short legs, sometimes just the front legs (2). These cats were just a curiosity, mostly among stray and feral populations, until the right cats met the right people. Sandra Hochenedel was a music teacher living in Rayville, Louisiana (5, 7, 8). In 1983, she rescued two pregnant stray cats that had been cornered by a dog (5, 8). She noticed that both queens were rather unusual–they had very short legs.

Hochenedel named the gray queen Blueberry and the black queen Blackberry (2, 5). She gave away Blueberry and kept Blackberry, who gave birth to a litter of both wildtype and short-legged kittens (2, 5, 7, 9). Hochenedel gave one of the kittens, a short-legged tom named Toulouse, to her friend Kay LaFrance in Monroe, Louisiana (2, 5, 10). Blackberry had a few more litters before disappearing (2, 5).

LaFrance kept her cats intact and free-roaming, and Toulouse soon began to sire a sizable population of short-legged cats in Monroe (5). Seeing the little cats proliferate and survive on their own, Hochenedel and LaFrance wondered if they had a new breed on their hands. They named the cats Munchkins after the diminutive people in The Wizard of Oz (1, 5, 8). They wrote a breed standard, established a breeding program, and recruited other breeders (5). The Munchkin was publicly unveiled in 1991 at the INCATS TICA cat show in Madison Square Garden (5). The response was mixed, and TICA refused a request to recognize the breed the same year (5). However, in 1994 TICA changed their mind and accepted the Munchkin into their New Breed Development program (5, 6, 10). TICA accepted Munchkins for Championship status in 2003 (1, 5, 6, 10).

A handful of other cat fancy organizations have accepted the Munchkin since TICA, but the other major groups still refuse to recognize it (5, 8). Some have gone out of their way to ban the Munchkin and any breed like it (5). The Fédération Internationale Féline (FIFe) made an addition to their rules forbidding “showing as a breed characteristic a dominant gene resulting in shortened limbs and legs and other physical defects, for example, the Munchkin” (5). It could not be more clear which breed they had in mind. The Munchkin is a breed that cat fanciers don’t seem to find much middle ground on.

Characteristics

Appearance

The defining characteristic of Munchkins is, of course, the legs. Their legs are about three inches shorter than the average cat’s (1). The upper and lower parts of their legs are about the same length (5). The hind legs are often a little longer than the front legs, and Munchkins can be slightly bow-legged (7). There is such a thing as a long-legged Munchkin, believe it or not. Long-legged cats born in Munchkin breeding programs are called non-standard Munchkins. Their short-legged peers are standard Munchkins.

Tuxedo Munchkin on steps — My Aunt and Uncle’s random-bred “Munchkin,” Jinxy – Photo by Dorenda Adkins

The short legs are the result of a spontaneous genetic mutation. The mutation in the UGDH gene causes abnormal limb development (9). Munchkins end up born with shorter, thicker long bones in their legs (3, 5, 8, 9). The UGDH mutation is a dominant trait, which means that kittens only need to inherit it from one parent to have short legs (1, 4-10).

In the case of Munchkins, they only can inherit it from one parent. While the short legs may be a dominant trait, the same mutation is also recessive lethal (1, 4, 7, 9). This means that if a kitten inherits the mutation from both parents, it dies before birth. This is why Munchkins have small litters and all Munchkins have both long- and short-legged kittens.

To avoid any kittens inheriting the mutation from both parents, standard Munchkins are usually bred either to non-standard Munchkins or to Domestic Shorthair/Longhairs. This has made the Munchkin a very diverse breed. They can be any color or pattern with short or long fur. However, they still have to conform to a breed standard to be a Munchkin. They are not just short cats. They should have a medium-boned body with a back that slopes gently upward toward the tail. The head is a rounded wedge with high cheekbones and a flat forehead. The eyes are wideset.

Munchkins will carry their tail upright when in motion. It should taper to a rounded tip and be the same length as their body. Both shorthairs and longhairs have moderate, resilient fur, much as you would expect for cats recently descended from random-bred strays.

Personality

People often think that Munchkins are sluggish because of their stubby legs, but that couldn’t be further from the truth. Munchkins are extroverted and energetic! They love to play, explore, and run like crazy, just like most cats. If a Munchkin wants to check out something that’s a teeny bit beyond their sight, they will sit up on their haunches like a rabbit to get a better look. They are perfectly capable climbers. The short legs do prevent them from jumping as high as other cats, but they can and do jump. And when a cat has a will, they will certainly find a way, so don’t assume they can’t get on top of something.

These sociable cats pretty much like to hang out with anybody. They fit well into homes with children and other pets. In busy households, though, it’s important to keep in mind that Munchkins have a tendency to hoard small objects. If your favorite watch has gone missing, and everyone says they didn’t take it, you might want to check the cat bed. Munchkins are an intelligent breed, so if thievery has become a problem, perhaps some food puzzles or other enrichment activities might help keep your kitty’s mind occupied. Then again, cats will be cats.

Munchkins sometimes sit up on their back legs like bunnies!

Caring for Your Munchkin

You might expect Munchkins to need a lot of accommodations due to their stature, but they usually don’t. Regular food and water bowls should do fine (7). There might be instances when they would appreciate pet stairs to get up somewhere high, but that really depends upon your furniture. Munchkins are low-maintenance when it comes to grooming, too. Probably the most important thing is that they have plenty of space to run and play. These cats can work up a lot of speed and take corners like it’s nothing (1, 5, 7, 8). A cluttered floor is no fun for a Munchkin.

Health Concerns

Tabby Munchkin kitten — Photo by Tran Mau Tri Tam on Unsplash

There has been a lot of debate about whether breeding Munchkins is ethical because it perpetuates a deformity. After all, dog from breeds with similar mutations frequently suffer painful health problems. There are cases of short-legged cats that have deleterious effects as a result of their deformity as well (2, 3). With Munchkins, however, this doesn’t seem to be the case.

Munchkins don’t usually have the musculoskeletal problems that short-legged dogs do because the feline spine is built differently than the canine (10). And while Munchkins have a form of dwarfism, the mutation they have doesn’t cause the conditions that other forms of dwarfism often do (4).

Munchkins do have a higher risk of lordosis than other cats (2, 7). Lordosis of the spine–not to be confused with the she-cat mating position also called lordosis–is a condition where the spine curves too far inward. It is often painful and may even put pressure on the internal organs. Conversely, Munchkins have an elevated risk of pectus excavatum as well (2, 7). Pectus excavatum occurs when the breastbone is sunken into the chest, compressing the chest cavity.

As pedigreed cats go, though, Munchkins are quite healthy. The large amount of Domestic Shorthairs and Domestic Longhairs, cat fancy language for “mutts,” in the gene pool probably has a lot to do with that. After all, most if not all Munchkins can still trace their family tree back to Blackberry and Toulouse, two random-bred cats roaming Louisiana on their stubby legs.

Fun Facts

The shortest living cat, according to the Guinness Book of World Records, is a Munchkin named Lilieput. She is a tortoiseshell from Napa, California, and she stands 5.35 inches (13.34 cm) at the shoulders. (1)
Paris Hilton has two Munchkins, or “low-rider kitties” as she calls them. Their names are Shorty and Munchkin. (1)
Munchkins have been bred with other pedigreed cats to create unofficial “Munchkinized” breeds. There are are now short-legged cats with curly hair, hairlessness, curly ears, and smushed faces. One line has been bred to resemble the jaguarundi wild cat. (2)

Works Cited

Braaksma, H. and Guthrie, C. (2021, April 25). Munchkin. Daily Paws. https://www.dailypaws.com/cats-kittens/cat-breeds/munchkin
Hartwell, S. (2005). Short-legged cats. Messy Beast. http://messybeast.com/shortlegs.htm
International Cat Care. (2018, October 3). Munchkin. https://icatcare.org/advice/munchkin/
Lyons, L. A., Fox, D. B., Chesney, K. L., Britt, L. G., et al. (2019). Localization of a feline autosomal dominant dwarfism locus: A novel model of chondrodysplasia. https://doi.org/10.1101/687210 [Retrieved from Cold Spring Harbor Laboratory bioRxiv database]
Munchkin. (n.d.). Petfinder. https://www.petfinder.com/cat-breeds/munchkin/
Munchkin. (n.d.). Vetstreet. http://www.vetstreet.com/cats/munchkin
Munchkin cat: Story in a nutshell. (2019, August 16). Basepaws. https://basepaws.com/blogs/news/munchkin-cat-breed
Sorocco, E. (2017). 11 things to know about the munchkin cat. Catster. https://www.catster.com/cats-101/about-the-munchkin-cat
Struck, A., Braun, M., Detering, K. A., Dziallas, P., et al. (2020). A structural UGDH variant associated with standard munchkin cats. BMC Genetics, 21. https://doi.org/10.1186/s12863-020-00875-x
The International Cat Association. (2018, August 13). Munchkin breed. TICA. https://tica.org/breeds/browse-all-breeds?view=article&id=857:munchkin-breed&catid=79

Published July 11, 2021

Breed Profiles

Egyptian Mau: Cat of the Pharaohs

March 14, 2021May 12, 2023 mehshadoweye

Meredith Hemphill

mehshadoweye

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

Bronze Egyptian Mau cat — Bronze Egyptian Mau – Image by liz west via Wikimedia Commons

The art of the ancient Egyptians frequently depicts cats, an animal which they considered sacred. The cats in their artwork bear a striking resemblance to a modern cat breed, the Egyptian Mau. Some believe that Egyptian Maus are actually the direct descendants of those ancient cats, a divine bloodline carried through the feral street cats of Cairo and into these pedigreed beauties. Maybe that’s true and maybe it isn’t. Egyptian Maus are special in their own right, and no cat needs to be told they deserve to be worshipped.

The male cat is Ra himself, and he is called by reason of the speech of the god Sa, who said concerning him, “He is like unto that which he hath made, thus his name became ‘Mau.'”
Egyptian Book of the Dead, 240 BCE

Along the River Nile?

According to legend, the history of the Egyptian Mau goes all the way back to ancient Egypt. Egyptian art and papyri dating as far back as 1550 BCE show similar spotted cats (9). The cats are shown assisting on duck hunts as well as in religious contexts (8, 9). However, we only know for sure that the Egyptian Mau was bred and shown in Europe in the early twentieth century (2, 4, 7, 8). Then World War II broke out, and cat fancy was one of the many things to be interrupted. Many breeding programs fell by the wayside during the war, and at its end very few Egyptian Maus remained (2, 4, 7, 8). The breed needed a hero, but not a knight in shining armor. They needed a princess to save them.

Princess Natalie Troubetskoy (or Trubetskaya) was living in exile in Rome (2, 4, 7, 8, 10). While there, she was given a silver, spotted female kitten (2). In one version of the story, the kitten came from a boy who had been keeping her in a shoebox (2). In another, the Egyptian ambassador to Italy gave her to Princess Natalie (2, 5). The princess named the kitten Baba (2, 8). She loved Baba’s unusual spotted coat. Princess Natalie bred Baba, and Baba had two kittens: a silver female, Liza, and a bronze male, Jojo, both spotted like their mother (1, 10). Princess Natalie immigrated to New York City in 1956 and brought the three cats with her (1, 2, 4, 8, 10). There, she established the Fatima Cattery to breed Egyptian Maus and wrote a breed standard (2, 4, 7, 10).

The Egyptian Mau was well-received, but early breeders faced a serious dilemma. The gene pool was miniscule. Inbreeding was inevitable, and the cats soon began to have problems. Diseases included cardiomyopathy and asthma cropped up (10). Aggressive and disagreeable temperaments were a pervasive problem as well (7, 10). The only solution was to bring more cats into the breeding program. During the 1980s and 90s, cats with a similar type were imported from Egypt and India, including the Delhi Zoo (4, 5, 8, 10). Although Egyptian Maus remain a less common breed, the gene pool is now much larger, and the problems that were pervasive in early breeding lines have largely disappeared (10).

How Egyptian is the Egyptian Mau?

Phylogenetic tree showing genetic relatedness of 24 cat breeds – Menotti-Raymond et al., 2008, Fig. 4

Genetic tools enable all kinds of interesting discoveries. Apparently I’m 0.4% Coptic Egyptian. But how Egyptian is the Egyptian Mau? The long-standing narrative assumes a direct line of descent from African wildcats to ancient Egyptian domestic cats to Egyptian Maus. Studies of the genetic variance between cat breeds and populations of non-pedigreed cats throws a monkey wrench into that story, however.

Genetic studies suggest significant European influences on the Egyptian Mau (4-6, 8). The waters are a bit muddy even here. Egyptian Maus were found to be more closely related to random-bred cats from Turkey and Tunisia than those from Egypt (5). A mitochondrial DNA analysis, which follows the maternal line, grouped Egyptian Maus with the Siamese, Russian Blue, Abyssinian, and Korat (5). Those breeds all have an Asian origin. Later studies using different methods have grouped the Egyptian Mau with Turkish Angoras and Turkish Vans (5, 6). A Turkish origin seems likely, based on the genetic evidence. As little is known about the breed before Princess Natalie revived it, pretty much anything is on the table.

Breed Characteristics

House Cheetahs

The thing that makes Egyptian Maus stand out is their spots. In fact, they are the only* naturally spotted breed of cat. This means that no one selectively bred them to try to engineer a spotted coat. They did it all on their own. Cat fanciers and cat people in general liked how their spotted coats resemble a wild cat. But these kitties aren’t hybrids like Savannahs and Bengals. They just look the part.

Their dark spots cover the body but can vary in shape and size (3, 10). They have “vest button” spots lining their pale undersides (1, 2). Egyptian Maus have a dark stripe running alone the length of their backs and tails (1). Their facial markings stand out as well. An M on their foreheads marks Egyptian Maus as a type of tabby, although you might not think of a spotted cat that way (1-4, 8). In this breed, that M is sometimes called “the mark of the scarab” because it allegedly resembles the pattern on the shell of the scarab beetle (3, 8). Egyptian Maus also have stripes resembling eyeliner running from the outer corner of each eye (1, 2, 4, 8). Their tails have dark stripes and tips (1, 4).

Only three colors of Egyptian Mau are accepted for showing: silver, bronze, and smoke. The silver has black markings on a light gray base. The bronze is thought to most closely resemble the cats of ancient Egypt, based upon the art they left behind (3). It has dark brown or black markings on a light brown base color. The smoke has solid black markings on a black smoke coat, where each hair is white with a black tip. The breed does come in a few other colors, including solids, but only as pets.

CFA Premier Shainefer’s Albion Argent, a silver Egyptian Mau – Image by Catbar via Wikimedia Commons

The Egyptian Mau is a medium-sized cat with a muscular yet graceful body. The hind legs are a little longer than the forelegs. Egyptian Maus have a flap of loose skin from their flanks to their hind knees which enables their back legs to stretch out farther when running (4, 7-10). Cheetah’s have a similar skin fold. This enables Egyptian Maus to be incredible runners and jumpers (4, 8-10).

Their heads strongly resemble ancient Egyptian depictions of cats. The shape is a rounded wedge with medium-to-large ears set well apart. The eyes are large, almond-shaped, and slant slightly upward. They are a characteristic gooseberry green color. Kittens can take a while to fully develop this eye color, and it sometimes becomes paler with age.

*The only recognized one, that is. There are others, such as the Bahraini Dilmun Cat, but they are not recognized by any cat fancy association.

Personality

Egyptian Maus are fiercely loyal cats. They bond strongly to their person or family. These cats are people-oriented and enjoy spending time with whoever they taken a shine to. They usually don’t like strangers and tend to hide around guests. Socialization at a young age is important to help them be as social as possible. If you adopt an adult Egyptian Mau, don’t be surprised if it takes a while for them to warm up to you. They just need extra patience. The wait will be worth it.

Egyptian Maus communicate quietly and charmingly. They typically use softer vocalizations like chirps and one all their own called a chortle. When pleased, they tread their feet. If excited, they “wiggle tail.” Incidentally, my Joon does this too, and it is truly bizarre. It looks like what cats do with their tails when they’re spraying, but without the spraying. I’m sort of relieved to know other cats do that, too. I digress.

The Egyptian Mau is an active breed. They enjoy games and puzzles, and some even like to play in water. Fetch tends to be a favorite. They can sometimes be possessive, including of their toys, so supervise an Egyptian Mau when they’re playing with a child or another animal until you know what to expect.

Egyptian Mau vs. Fish Toy

Caring for an Egyptian Mau

The Egyptian Mau is not known to have breed-specific health problems anymore. The addition of new, random-bred cats to the breeding population turned it into a very healthy breed. They don’t require extensive grooming, either, just the occasional brushing that any shorthair benefits from. As far as pedigreed cats go, Egyptian Maus are pretty low-maintenance, but there are some things to keep in mind.

While not hyperactive, these are athletic cats that will need plenty of places to climb. They may be good candidates for leash walking to work those long legs. Don’t forget that they are excellent jumpers, so they can probably reach heights that many cats couldn’t. Deprive them of a cat tree at your peril. They are excellent hunters, so playtime that mimics natural hunting behavior–and gets their favorite human involved–is a great way to give them some exercise, too.

Egyptian Maus get along pretty well with children, other cats, and dogs, as long as they are properly introduced. Remember, though, they aren’t fond of strangers, so new pets need to be introduced very carefully and slowly. An Egyptian Mau that wasn’t well-socialized to other animals as a kitten may not be able to cope at all. Proceed with caution. When it comes to small animals, proceed with even greater caution. The Egyptian Mau loves to hunt. Unfortunately, they see pet birds, rodents, etc. no differently than any other prey animal and might kill them (2, 8). If you have any pets that a cat might see as prey, make absolutely sure that your Egyptian Mau cannot get to them.

If you are considering an Egyptian Mau of your very own, try the CFA Egyptian Mau Breed Council Rescue or The Egyptian Mau Club‘s re-homing list. You can also check with your local shelters. Purebred go to the pound, too.

Fun Facts

The word “mau” comes from the Middle Egyptian “mjw,” meaning both “cat” and “sun.” (3, 6)
Egyptian Maus often don’t lose their baby teeth until their permanent teeth have already come in. This means, sometime between four and seven months old, they can have two full sets of teeth! (10)
The Egyptian Mau gestation period is longer than usual for cats. Most cats kit after about 63 days, but Egyptian Maus can have their kittens a week later with no problems. (4, 10)
The Egyptian Mau is the fastest breed of domestic cat. They can run at speeds up to 30 mph (48.3 kph)! (2, 4, 8)

Works Cited

Alderton, D. (1992). Cats: The visual guide to more than 250 types of cats from around the world. Dorling Kindersley Limited: London.
CatTime. (n.d.). Egyptian Mau. TotallyHer Media, LLC. https://cattime.com/cat-breeds/egyptian-mau-cats#/slide/1
Edwards, A. (2006). The ultimate encyclopedia of cat, cat breeds, and cat care. Hermes House: London.
Fawcett, K. (2016, June 24). 6 fast facts about Egyptian Mau cats. Mental Floss. https://www.mentalfloss.com/article/81610/6-fast-facts-about-egyptian-mau-cats
Hartwell, S. (2013). Cat-breed DNA studies: True origins or legitimising impostors? Messybeast.com. http://messybeast.com/dna-studies-critique.htm
Menotti-Raymond, M., David, V. A., Pflueger, S. M., Lindblad-Toh, K., et al. (2008). Patterns of molecular genetic variation among cat breeds. Genomics, 91(1), 1-11. https://doi.org/10.1016/j.ygeno.2007.08.008
Petfinder. (n.d.). Egyptian Mau. https://www.petfinder.com/cat-breeds/egyptian-mau/
Syufy, F. (2019, September 22). Egyptian Mau: Cat breed profile. The Spruce Pets. https://www.thesprucepets.com/egyptian-mau-breed-profile-554215
The Cat Fanciers’ Association. (n.d.). About the Egyptian Mau. CFA.org. https://cfa.org/egyptian-mau/
The Egyptian Mau. (2002). CFA.org. https://cfa.org/egyptian-mau/egyptian-mau-article-2002/

Published March 14, 2021

Science

Coat Length and Texture Genetics

November 1, 2020June 14, 2023 mehshadoweye

Meredith Hemphill

mehshadoweye

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

By special request from Emma S.

I am back with the genetics! A friend asked me if I was going to address the genetics of cat fur length in addition to my previous blogs on coat genetics. I wasn’t sure there was enough information to fill up a whole blog, but I dove in anyway. It turns out, there’s plenty. It’s not just the difference between a longhair and a shorthair, but also hairless cats and sort-of-hairless cats and curly-haired cats. Cats are complicated. Genetics is complicated. That’s kind of the fun of it, though. So, this one is for you, Emma. Enjoy.

Longhair ginger tabby cat in autumn woods — Long hair is recessive to short hair – Photo by Steven Iodice from Pixabay

Shorthair vs. Longhair

Let’s start with the basics. If you need a refresher on the principles of genetics, look over the first few paragraphs of my coat color genetics post. Ready? Let’s go. The wild-type, or default, fur for cats is short with no texture modifications. Long hair is recessive to short hair [1-4]. This has been common wisdom for a while, but genetic studies confirmed it in 2007 [1, 2].

The researchers discovered four mutations in the same gene, Fibroblast Growth Factor 5 (FGF5), which cause cats to have long fur [1, 2]. FGF5 mutations were already known to cause hair-length variability in mice and dogs at the time the studies were conducted, so this was not a surprising result [1, 2]. In studies with mice, the FGF5 protein signaled hair to exit the growth phase and enter the static phase [2]. When mutations in FGF5 cause the protein to be nonfunctional, the growth phase of the hair lasts longer [2]. Hence, longer fur.

The four FGF5 mutations in long-haired cats were, creatively, named Mutation 1-4 [2, 3]. Mutation 1 seems to be exclusive to Ragdoll cats [2]. Mutation 2 was only found in Norwegian Forest Cats [1, 2]. Maine Coons are most likely to have Mutation 3, but Ragdolls might as well [1, 2]. Mutation 4 belongs to all long-haired breeds and random-bred longhairs [1, 2]. So far, there is not indication that any gene besides FGF5 contributes to the longhair phenotype. The fact that at least four mutations in this gene exist, three of them breed-specific, suggests that the trait has arisen multiple times through a similar mechanism. This is probably because, in certain environments, long fur is advantageous. It has also sometimes been artificially selected for.

Now, we know that there are not just two lengths of cat fur, one long and one short. There are many variations within both the shorthair and longhair categories, and some cats are kind of in-between. This is because very few things are affected by just one gene. An unknown number of modifier genes determine the exact length of a cat’s hair relative to their genotype at the primary hair length locus [4].

Hairless, or Near Enough

Some cats or breeds are more or less hairless. True hairlessness is almost unheard of. Hairless cats present with a variety of traits that we call “hairless.” Most have very thin coats that look as if they aren’t there at all. Some have fur that thins drastically in only certain places. In either case, the degree of “hairlessness” can vary widely. As one would expect with so much natural variation, more than one mutation causes the different patterns of feline hairlessness. Sometimes the trait is dominant, and sometimes it is recessive [3, 4].

Four cream Sphynx kittens on blue cat bed — The Sphynx trait is caused by the hr mutation – Image by mjlovesmm from Pixabay

A recessive mutation dubbed hr gives the easily-identifiable Sphynx its hairless phenotype [3, 4, 5]. The Sphynx is a typical hairless breed with an extremely thin, downy coat that gives the appearance of baldness [5]. The hr allele is a mutation in the Keratin 71 (KRT71) gene [5]. The keratin 71 protein is expressed in the inner root sheath of the hair follicle and is important for the normal formation of the hair [5]. The hr mutation does not prevent hair from forming, but the hairs are easily dislodged because the hair bulbs are weak, resulting in the distinctive naked appearance of the Sphynx [5].

The Russian hairless breeds, Peterbald and Donskoy, carry the semi-dominant Hp mutation [4, 6]. Other genes affect how strongly the Hp hairlessness allele is expressed [4, 6]. The cats’ coats range from a brush coat–sparse, rigid, curly fur–to hairless all over [4]. Hairless mutations identified in British and French cats, hd and h respectively, are recessive [3, 4]. Sadly, hd is also a lethal mutation [4].

The Lykoi breed displays partial hairlessness. They have a thin coat all over and a hairless face, sometimes with other patches of hairless, especially on the legs. Lykoi molt all of their hair at least once in their life and may molt as often as every shedding season. This arguably makes them a breed that is truly hairless, albeit only for short periods of time. Six different mutations have been found to cause the Lykoi phenotype, but all of them are mutant alleles of the same gene, lysine demethylase and nuclear receptor corepressor, abbreviated HR for “hairless” [7]. Mutations in HR also cause hair abnormalities in humans, mice, sheep, and macaques [7].

Rexoid Variations

Curly fur occurs naturally in quite a few mammals, including dogs, rabbits, and cats. There are five recognized breeds of curly-coated cats, per the Cat Fanciers’ Association and The International Cat Association: American Wirehair, Cornish Rex, Devon Rex, LaPerm, and Selkirk Rex. Several other potential rexoid breeds have been proposed, including the German Rex and Oregon Rex. While all of these cats–and some random-bred cats–have curly coats, there are a lot of different causal mutations.

Remember the KRT71 gene? One kind of mutation in it causes the Sphynx’s hairlessness, but a different KRT71 mutation makes the Devon Rex’s pelt curly [5]. The Devon Rex mutant allele, re, is recessive to the wild-type allele but also to the hr Sphynx allele [5]. Devon Rex cats were used in the early Sphynx breeding programs, so some Sphynx still have one hr and one re allele, but they look just like any other Sphynx [5].

Lilac cat with curly fur on wood table — Selkirk Rexes can have long or short hair – Image by athree23 from Pixabay

A recessive mutation also causes the Cornish Rex’s curly coat, but in their case the gene in question is lysophosphatidic acid receptor 6 (LPAR6) [8]. The mutant allele, known as r, causes the Cornish Rex to only develop an undercoat, one of the three layers of a normal pelt, and a curly one at that [8, 9]. Humans who are homozygous for LPAR6 mutations have a similar phenotype known as “wooly hair” [8]. Because the Cornish Rex was used to found the German Rex, r is in the genetic background of German Rexes, too [8].

Unlike the Devon and Cornish, the Selkirk Rex mutation, Se, is dominant, although incompletely dominant [9]. This means that cats homozygous for the mutation have a more dramatic phenotype: thinner coats, tighter curls [9]. And, wouldn’t you know it, Se is an unique mutation of our old friend, KRT71 [10]. Both KRT71 and LPAR6 are genes that maintain normal hair growth [5, 8]. It makes sense that different mutations in the same or similar genes would cause similar results.

Works Cited

Drögemüller, C., Rüfenacht, S., Wichert, B., and Leeb, T. (2007). Mutations within the FGF5 gene are associated with hair length in cats. Animal Genetics, 38(3), 218-221. https://doi.org/10.1111/j.1365-2052.2007.01590.x
Kehler, J.S., David, V.A., Schäffer, A.A., Bajema, K., et al. (2007). Four independent mutations in the feline Fibroblast Growth Factor 5 gene determine the long-haired phenotype in domestic cats. Journal of Heredity, 98(6), 555-566. https://doi.org/10.1093/jhered/esm072
Basepaws. (2019, July 14). Cat coat genetics. Basepaws, Inc. https://www.basepaws.com/blog/cat-coat-genetics/
Hartwell, S. (n.d.) Genetics of colour and conformation. MessyBeast. http://messybeast.com/cat-genetics-basics.htm
Gandolfi, B., Outerbridge, C.A., Beresford, L.G., Myers, J.A., et al. (2010). The naked truth: Sphynx and Devon Rex cat breed mutations in KRT71. Mammalian Genome, 21, 509-515. https://doi.org/10.1007/s00335-010-9290-6
Zhigachev, A.I., Vladimirova, M.V., and Katser, I. (2000). Phenotypic and genotypic characteristics of Russian hairless cats. Genetika, 36(4), 538-544. https://europepmc.org/article/med/10822817
Buckley, R.M., Gandolfi, B., Creighton, E.K., Pyne, C.A., et al. (2020). Werewolf, there wolf: variants in Hairless associated with hypotrichia and roaning in the lykoi cat breed. Genes, 11(6), 682. https://doi.org/10.3390/genes11060682
Gandolfi, B., Alhaddad, H., Affolter, V.K., Brockman, J., 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
Basepaws. (2019, July 15). Curly cat coat: A special kind of eye candy. Basepaws, Inc. https://www.basepaws.com/blog/curly-cat-coat/
Gandolfi, B., Alhaddad, H., Joslin, S.E.K., Khan, R., et al. (2013). A splice variant in KRT71 is associated with curly coat phenotype of Selkirk Rex cats. Scientific Reports 3, 2000. https://doi.org/10.1038/srep02000

Published November 1st, 2020

Updated June 14th, 2023

Science

Coat Pattern Genetics

April 10, 2020June 14, 2023 mehshadoweye

Meredith Hemphill

mehshadoweye

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

A few weeks ago I wrote about the genetics of coat color in domestic cats. Now, to follow up, I am going to dive into the wild world of pattern genetics. If you would like a review of basic genetic principles, click the link to the previous article. There is a quick rundown in the beginning.

In genetics, the “wild type” is the genetic profile of an organism that is most common under natural conditions. The wild type ancestral cat was a mackerel tabby with black stripes, short fur, and no white spots [1]. Today, of course, cats come in a wide variety of patterns, even those who live feral and are subject to natural selection. Both human intervention and spontaneous mutations are to credit for this diversity.

Tabby

Let’s start with tabbies, the original cat pattern. Many other cat species share the tabby pattern with domestic cats, usually in the form of rows of spots–spots and stripes are closely related genetically in cats [2, 3]. In order to have a tabby pattern, a cat must first have at least one dominant allele at the agouti locus. The dominant agouti allele causes each individual hair to have bands of darker and lighter pigmentation. This is required for tabby coats and several other patterns which we will come to later.

The wild type mackerel tabby pattern is characterized by thin, parallel stripes darker than the background color. Mackerel tabby is the dominant allele at the Tabby, or Ta, locus, so only one TaM allele is required for the mackerel tabby pattern. The “blotched” or “classic” tabby has large, marbled stripes. This pattern occurs at the same Ta locus. The blotched allele is recessive to the mackerel.

Spotted tabby kitten with toys — Spotted tabby kitten – Photo by Kim Davies on Unsplash

At least two other alleles are involved in tabby patterning, although it was previously thought that there was only one [4]. The Ticked locus has been definitively identified as influencing the type of tabby pattern a cat’s coat has, but another unknown locus or loci may effect how the patterns present [4].

The Ticked locus is epistatic to the Tabby locus, meaning that the genotype at the Ticked locus has an impact on the phenotype coded for by the Tabby locus. If a TiA allele is present at the Ticked locus, the cat will have ticked/agouti fur all over the body, as the TiA allele masks the effect of the Tabby locus. This is usually called an Abyssinian Tabby because the ticked coat is characteristic of the Abyssinian breed. If there are two Ti+ alleles, the cat will not be an Abyssinian tabby, and whatever genotype is at the Tabby locus will show through. Cats with one TiA and one Ti+ allele tend to have some striping on their faces, legs, and tails despite being Abyssinian tabbies.

Tired of talking about tabbies? I hope not, because we still have to go over the special cases! Spotted tabbies have stripes that are broken into spots of varying size. An unknown modifier gene or genes are believed to alter the expression of mackerel tabby stripes to create spotted tabbies [4]. The charcoal Bengal/Savannah patterns are a variety of tabby caused by an agouti gene inherited from the Asian Leopard Cat. Charcoal tabbies have decreased red tones in their coats, giving them a cooler, grayer appearance. They also have a dark nose and “Zorro” mask on the face and a dark cape down the back. There are a shocking number of other types of modified tabby, but the genetics behind them are hazy. I will leave you with a handy infographic showing you what they look like and move on to the next pattern.

Table of tabby patterns — Chart of Tabby Patterns – Image from messybeast.com

Silver and Gold

Agouti hairs would normally have alternating bands of light and dark pigment corresponding to the cat’s coloring, but there are a couple genes, or possibly gene families, which can change the way pigment is deposited on agouti fur. A dominant mutation of the Silver/Inhibitor gene inhibits production of phaeomelanin, the yellow or red pigment in cat hair. This causes the light portions of agouti bands to be very pale or colorless rather than yellow. This mutation, by itself, causes tabbies to be silvery and solid-colored cats to have a pattern known as smoke, where there is a pale/colorless band at the bottom of their hair shafts. Their white undercoats give them a “smoky” appearance when their fur is ruffled.

On the other hand is the Wide-Banding trait, only present in agouti cats. It is thought to be caused by a group of related genes, but this is still unclear, and no one quite knows how they work. Whatever the root cause, wide-banding causes the agouti bands on the hair shaft to be larger and/or more numerous. There is a high degree of variation in the way this can present, lending credence to the idea that there is more than one gene involved.

Silver Persian and kitten in cat tree — Silver shaded Persian (top) – Image by RomeoEbaloo from Pixabay

When Wide-Banding occurs alone, the cats are sometimes referred to as “golden” due to the higher degree of yellow pigment in their coats. However, the Silver and Wide-Banding traits can occur together to create other patterns. In either case, cats with Wide-Banding that leaves only the very tip of the hair shaft to show their normal pigmentation are said to be tipped. Those with more of the darker pigment on the end of the shaft are called shaded. There are even more names among cat fanciers for the many different combinations of these phenotypes, but we have more to cover.

Color-point

We touched on color-pointing in the Siamese breed profile, and we will probably circle back to it with other breeds. It is a popular pattern which has been deliberately bred into quite a few breeds. Color-pointing is a kind of partial albinism. These cats have a mutation in tyrosinase, an enzyme required for the production of melanin. The mutated enzyme will only activate below 33 degrees Celsius. As such, the mutation causes temperature-sensitive pigmentation, with the most color deposited on the coolest extremities of the body. There are actually two color-point alleles that result in three somewhat different phenotypes. Both alleles are recessive to the wild type allele but are codominant to each other.

Brown and cream cat with blue eyes — Tabby Himalayan color-point – Photo by Nathz Guardia on Unsplash

The Himalayan phenotype has the strongest color restriction. It is seen in cats with two cs alleles. These cats have blue eyes and a very light-colored torso, typically cream or ivory. The color-pointing is very high-contrast. The intermediate phenotype is known as Mink and is typical of the Tonkinese breed. They have one cs allele and one cb allele. The eyes are aqua and the torso color is more similar to the points.

The Sepia color-points are not all sepia but are named for the brown Burmese cats wherein the pattern was first identified. This phenotype has copper eyes and is quite low-contrast, with the points and the torso being fairly similar in color. Sepia color-points have two cb alleles. All color-point cats can have points of any color, and the points can also be patterned. Sometimes color-point and white spot patterns can be combined to form new patterns, such as white mittens (characteristic of Birmans) or bicolor. For more on white spots, see the coat color article.

There are a LOT of miscellaneous mutations that I could talk about which are not so widespread or well-documented as the ones I have covered here today. If you would like me to go over them in the future, please let me know. I would be glad to do so. You can also tell me if you never want me to do this again. Feedback is always welcome. :3

Works Cited

Hampton, N. (1998, March 4). Coat color and pattern genetics of the domestic cat (Felis catus) [PowerPoint slides]. The University of Texas at Austin. https://facultystaff.richmond.edu/~lrunyenj/bio554/cat/index.htm.
Thomas, E.M. (1994). The tribe of tiger: Cats and their culture. Simon and Schuster.
Zielinksi, S. (2012, September 20). Same gene guides cheetah and tabby cat coat patterns. Smithsonian Magazine. Link here.
Eizirik, E., et al. (2010). Defining and mapping mammalian coat pattern genes: Multiple genomic regions implicated in domestic cat stripes and spots. Genetics, 184(1), 267-75. DOI: 10.1534/genetics.109.109629

Published April 10th, 2020

Updated June 14th, 2023

Science

Coat Color Genetics

February 20, 2020May 12, 2023 mehshadoweye

Meredith Hemphill

mehshadoweye

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

Five tabby kittens — Colorful kittens – Photo from Pixabay

I majored in genetics as an undergraduate, so whenever I see a cat with unusual patterning or coloration, I can’t help but wonder what molecular wizardry made that possible. Cat fanciers have long wanted to unlock the mysteries of feline traits. While breeders began to puzzle out the patterns before DNA was determined to be the blueprint of heredity, there are still some mysteries to be solved. However, the more obvious traits have been mapped onto the feline genome, and there are even DNA tests for breeders or uncommonly curious pet owners who want to know what genes their cats carry. Today I want to cover the basics of coat color genetics, but I’ll start with a quick overview of genetics so no one gets lost. Feel free to skip it if you know you don’t need it.

Genetics: A Primer

DNA (deoxyribonucleic acid) is the molecule on which all the necessary information to build an organism is stored. Each unit of storage in the DNA is called a gene, and genes code for proteins. Proteins serve an incredibly wide variety of biological functions in the organism, including providing structure and metabolizing food into energy. There can be multiple different versions of a gene in the gene pool of a species. These different versions are called alleles.

Because an individual inherits half of their DNA from each of their parents, they have two copies of each gene. There are species for which this isn’t true, but it is for most vertebrates, including cats and humans. So each individual should have two copies of every gene, with a notable exception that we will get to later, but some alleles are dominant to others, so not every allele will be expressed. In the case of simple dominance, dominant alleles will be expressed if they are present. However, if the individual has inherited a recessive allele from both parents, they will express the recessive trait.

If you’re confused, I recommend looking up a more thorough overview of basic genetics before proceeding. There is much more to be said on the point, and I will do my best to explain as I go along, but it is only going to be more complicated from here. Now, let’s talk about what makes cats so very colorful!

Tom and the Monochromatic Fur Coat

Cats have two coat color pigments: eumelanin, which is black or brown, and pheomelanin, which is red or yellow. The primary coat color gene produces eumelanin. There are three alleles. The dominant allele, B, leads to black fur. The b allele is recessive to B and produces less pigment, leading to a brown coat, sometimes called “chocolate.” The b1 allele is recessive to both B and b, and it leads to a light brown or “cinnamon” coat.

The pheomelanin gene has a dominant allele, XO, that produces a red/orange coat color instead of or in addition to the color at the black/brown locus. The recessive allele, Xo, produces no reddish pigment. The pheomelanin gene is different in that it is located on the X-chromosome. In mammals, females have two X-chromosomes and males have one X and one Y, with some exceptions because biology is complicated.

So tom cats only have one gene for orange pigment, which they inherit from their mother. That is why toms are either ginger or black, but only very rarely both. But she-cats can have a XO and a Xo allele, causing them to have patches of both orange and black. This pattern is called tortoiseshell, or calico if they also have white patches. Tortoiseshell and calico toms can be born if they have two X-chromosomes and a Y or a similar chromosomal anomaly.

White cat with plush cow — White cat with odd eyes. Also a cow. – Photo by Samson Andreea on Pexels

50 Shades of White

White patches are due to the piebald spotting gene, where the recessive, s, allele codes for no white. If a cat has just one dominant allele, S, less than half of their fur will be white, and the white patches are often restricted to the feet, face, chest, and underside. If they have two dominant alleles, more than half of the cat will be white. It’s possible that they may even be completely white.

There are two other ways that a cat may be white, genetically speaking. The dominant white gene, as the name suggests, produces solid white cats with at least one dominant W allele. These cats are likely to be deaf, especially those with blue eyes and odd eyes. Those with odd eyes tend to be deaf in the ear on the same side as the blue eye. Rarely, white cats may be albino. There are two alleles that cause albinism, both recessive and both defective versions of the allele coding for the tyrosine enzyme. Cats with two c alleles are true albinos and have a translucent white pelt with pink eyes. Two ca alleles produce a white coat with pale blue eyes. There is no association of deafness with albino cats.

A Dilute Shade of Pale

The dilution gene is capable of modifying the appearance of other colors. The dominant allele produces the normal coloration. Two recessive alleles causes the pigment granules to clump in the hair shaft and leave large areas without pigment. The result is a lighter, or diluted, coloring. Black cats become grey, known as “blue” in the breeding world. Chocolate becomes lilac, cinnamon becomes fawn, and ginger, or “red,” becomes cream.

This covers the basics, although certain breeds can have unique alleles, such as the amber allele at the orange locus in Norwegian Forest Cats. I will cover the genetics of coat patterns another week. Until then, enjoy this picture of my gorgeous blue-cream calico.

Published February 20, 2020

Updated June 20, 2022