Which human foods are toxic to cats?

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If you live in the United States, then Thanksgiving is coming up soon. If you live somewhere else, the winter holiday season is coming everywhere. Holidays often mean special food and family meals. While our pets may be family, that doesn’t mean they can eat all the same things we can. It’s never a good idea to feed pets from the table, but things happen. Scraps fall to the floor. Kids may not know any better. Some pets, my cat included, are incorrigible food thieves and will steal from any plate left unattended for a single second. Sometimes, it’s not a big deal. But there are certain human foods that are toxic to cats. Here are the ones to be extra careful about.

Fruits and Veggies

Alliums

Root vegetables in the genus Allium include onions, garlic, shallots, leeks, scallions, and chives. All are toxic to cats. They usually don’t pose a danger unless consumed in large amounts, but it’s always best to be safe. Alliums contain several chemicals, primarily n-propyl disulphide, which cause the hemoglobin in cats’ red blood cells to break down (1, 2). Affected cats become anemic, which can be very dangerous. There is no antidote, but there are effective treatments, so be sure to seek veterinary care for any suspected ingestion or worrying symptoms right away (1).

Toxicity is possible no matter what form the vegetable is in–cooked, raw, powdered, dehydrated, garlic bread, etc. Be particularly careful of adding broth to your cat’s food, which can be a good way to keep them hydrated as long as the broth doesn’t have any alliums in it (3).

Early symptoms of allium toxicity are usually gastrointestinal: nausea, vomiting, diarrhea, loss of appetite, and abdominal pain. If anemia sets in, a day or two after ingestion cats will experience pale gums, lethargy, weakness, jaundice, rapid heartrate, rapid/labored breathing, and dark urine ranging from orange to brown in color (1, 4). These symptoms mean an immediate vet visit is in order.

Grapes

It is well-established that dogs can develop fatal kidney failure from eating even small amounts of grapes, raisins, currants, or sultanas. No one is quite sure why. It also remains unclear whether cats are also susceptible. The current advice is to keep grapes away from cats just in case. They are extremely toxic in dogs, and no one wants to find out the hard way that cats are, too. The toxic dose in dogs is highly variable (1), so if you realize your cat has eaten any amount of grapes or grape products, i.e. raisins, go ahead and take them to the vet right away.

Avocado

Avocadoes are actually poisonous to quite a few animals, including birds, rabbits, and horses in addition to cats and dogs (1, 5). The leaves, bark, seed, and fruit of avocadoes contain a natural fungicide called persin (1, 2). While some animals are very sensitive to persin, cats usually experience only gastrointestinal upset (2). However, not much is known about the particulars of avocado toxicity yet, such as the lethal dose, so it’s best to use a lot of caution (1). In other words, watch that bowl of guacamole carefully, or better yet, don’t put it out where the cat can get into it.

When avocado toxicity does lead to serious or even fatal symptoms–most commonly in birds–it does so by causing fluid accumulation in the chest (1). Respiratory and cardiac symptoms should be taken seriously under any circumstances. If your cat did get into the guac, though, be on the lookout for them. They could indicate unusually serious poisoning.

Citrus

Citrus plants contain citric acid and essential oils in their stems, leaves, fruits, rinds, and seeds. These chemicals are toxic to cats (5, 6). Small amounts will only upset their stomachs, but a large ingestion can cause serious gastrointestinal distress and even central nervous system depression (5, 6). The fruit contains lower levels of the compounds than other parts of the plant, including the rind.

Coconut

The fresh meat and milk of coconuts contains oils that the feline digestive system doesn’t care for (5). Coconuts can give cats upset stomachs and diarrhea (5, 6). Small amounts may not give them any trouble, however, and it isn’t deadly by any means. Coconut water, on the other hand, can actually be dangerous. It contains high levels of potassium that are not safe for cats (5, 6).

Solanum

The genus Solanum, although part of the nightshade family, contains a lot of agriculturally important vegetables, including tomatoes and potatoes. But even these hold a dark secret. Green tomatoes and green, raw potatoes are poisonous to our cats (1, 2, 7). They contain a chemical called glycoalkaloid solanine which causes severe gastrointestinal symptoms when ingested (2).

Fortunately, glycoalkaloid solanine tastes bitter, as poisonous chemicals in nature usually do (2). Some cats won’t be deterred by this, however. We know this because cats have been poisoned by green tomatoes and potatoes (1). And I once had to pry my cat’s jaws open to get a pill out of her mouth that she was determined to chew up and consume. Those are pretty bitter, too, but that was not stopping her. Best to keep the ripening produce away from the cats, and be careful of any scraps. Especially if you’re making the time-honored Southern dish of fried green tomatoes.

Seeds and Pits

Speaking of scraps, there are several kinds of seeds and pits that can be poisonous even though the fruit itself is not. Apple seeds, apricot pits, cherry pits, and peach pits should all be carefully discarded where cats cannot get to them (7). On that note, it is important that any compost bins and trash cans where food is disposed of are cat-proof.

Beverages

Caffeine

All caffeinated beverages are toxic to cats. Caffeine itself is the culprit. Caffeine belongs to a class of chemicals called methylxanthines, which are toxic to pets (1, 4-6). Cats cannot handle nearly as much caffeine as humans can. A sip may not cause any problems, but too much caffeine can be very harmful or even fatal. Symptoms of caffeine poisoning in cats include hyperactivity, rapid heartrate, tremors, labored breathing, and seizures (3).

Alcohol

Alcohol is a part of the festivities for many people, but your cat should never participate. Cats are very sensitive to alcohol, and even tiny amounts can give them alcohol poisoning. If you suspect your cat has ingested any alcohol at all, treat it as an emergency. Alcohol poisoning can absolutely be fatal. The symptoms include lethargy, vomiting, diarrhea, labored breathing, lack of coordination, disorientation, tremors, and coma (1, 3-6).

To prevent poisoning, it’s important to prevent access. Open drinks should not be left sitting around. Of course, at a bustling family gathering or holiday party, this is easier said than done. If you don’t trust your guests to keep their glasses in hand or out of your cat’s reach, you may need to put the cat(s) up in a safe room for the duration of the event. Make sure to clean up any spills either way. Cats like to drink from puddles.

Milk

Milk and other dairy products are not toxic to cats, per se, but they can still make them sick. Adult cats are lactose intolerant and usually don’t handle dairy well. I already wrote an article about cats and milk. If you want to know more, you are welcome to read it. I see no need to reinvent the wheel.

Snacks and Scraps

Chocolate

Chocolate also contains methylxanthines: caffeine, which we already discussed, and theobromine (1, 6, 8). Theobromine is found naturally in cacao beans at a concentration of 1-2% (1). Different kinds of chocolate have varying amounts of theobromine. As a rule, the darker or less sweetened the chocolate, the more theobromine. Pets metabolize theobromine much slower than humans, so it doesn’t take much chocolate to lead to toxicity (1).

Symptoms of poisoning typically present in 6 to 12 hours of ingestion (1). They include vomiting, diarrhea, abdominal pain, increased thirst, increased urination, rapid or abnormal heartrate, labored breathing, tremors, seizures, and a drop in blood pressure (1, 3-6). Heart attacks, heart failure, coma, and death can result in severe cases (1, 3). If you think your cat has eaten chocolate, of any kind, take them to the vet. Be sure to tell the vet what kind of chocolate you think they ate and how much, as well as how recently (8). That provides a ballpark for the quantity of methylxanthines consumed (8).

Salt

All animals need some amount of sodium to be healthy, but it’s always possible to get too much of a good thing. If your cat eats too many salty human snacks, or licks up a bunch of straight-up salt for whatever reason, they’ll have adverse effects. I even heard of this happening with a cat licking someone’s salt lamp, although that might be an urban legend. What’s certain is that cats are not designed to eat a whole bag of potato chips. If they manage to steal away with one or two, don’t panic. But don’t make a habit of feeding them salty things.

As a cat starts to get a little too much salt in the system, they start to exhibit increased thirst and urination (5). Their body is trying to flush out the excess salt. If it succeeds, that may be the end of it. More serious salt poisoning, however, can lead to vomiting, diarrhea, tremors, high body temperature, seizures, and maybe even death (5, 6).

Nuts

Salted nuts present a particular problem vis-à-vis the above, but even plain nuts can be of concern. They aren’t poisonous, exactly, but they contain lots of oils and fats that can cause vomiting and diarrhea (5, 6). The feline digestive system isn’t really equipped to digest nuggets of plant fats like that. Pets are also sometimes allergic to peanuts just like humans are, so peanuts and peanut products pose an additional risk (1).

Yeast Dough

Although baked bread is safe enough for cats, if not especially nutritious, raw dough containing yeast is very, very dangerous. There are two problems, both of which could be deadly on their own. Fermenting yeast produces carbon dioxide, which causes it to rise, and alcohol. When eaten, the alcohol can cause alcohol poisoning, as described earlier. But the expanding dough can cause a host of problems as well. It can cause the stomach to bloat, or worse yet to twist, which can be life-threatening (5, 6). It can also block the digestive tract and may even require surgery to remove (3). A small amount of raw dough can quickly become a very serious health risk. Take your cat to the vet immediately if you suspect they have consumed any at all.

Xylitol

Xylitol is an artificial sweetener. It is common in lots of products, including gum, candy, baked goods, and toothpaste. It is non-toxic to humans but very toxic to dogs, and it remains unknown whether it is toxic to cats (2). Currently, it is advised to err on the side of caution and assume it may be toxic to cats.

In dogs and some other species, xylitol tricks the body into releasing insulin even though no real sugar is present in the blood stream (1, 5). The large, unnecessary insulin release causes a severe drop in blood sugar and may lead to liver failure and death (1, 2, 5). The symptoms in dogs include vomiting, lethargy, weakness, loss of coordination, and seizures (1, 5, 6). To be on the safe side, check to make sure anything you plan to feed your cat does not contain xylitol, and take them to the vet if they happen to eat anything that does.

Bones

I suspect you already know that bones are not toxic. And cats are carnivores, so wouldn’t bones be part of their natural diet? Yes, cats do crunch up little tiny prey bones in the wild. But feral cats do not hunt turkeys.

The problem with giving your cat bones to gnaw on is that the bones in the kind of animals humans eat are often too big for cats to consume. So they may choke, break their teeth, or splinter off pieces of bone that then stab into their mouths or throats or–well, nowhere is good, is it? Never just throw your cat a bone. Or your dog, for that matter, because they can have the same problems. So no, bones aren’t toxic, but I included them because they can be dangerous and it would be an easy mistake to make.

Works Cited

1. Kovalkovičová, N., Šutiaková, I., Pistl, J., and Šutiak, V. (2009). Some food toxic for pets. Interdisciplinary Toxicology, 2(3), 169-176. doi: 10.2478/v10102-009-0012-4
2. Syufy, F. (2020, June 22). Human foods that are toxic cats. The Spruce Pets. https://www.thesprucepets.com/human-food-and-cats-551947
3. Nicholas, J. (2017, November 20). 14 human foods you shouldn’t give to your cat. Preventive Vet. https://www.preventivevet.com/cats/human-foods-you-should-not-give-to-your-cat
4. Hill’s Pet. (2019, October 30). Foods that are dangerous or toxic to cats. Hill’s Pet Nutrition, Inc. https://www.hillspet.com/cat-care/nutrition-feeding/toxic-foods-for-cats
5. ASPCA Poison Control Center. (n.d.). People foods to avoid feeding your pets. https://www.aspca.org/pet-care/animal-poison-control/people-foods-avoid-feeding-your-pets
6. Dowdy, S.M. (2020, August 24). 15 toxic human foods you should never feed your cat. Daily Paws. https://www.dailypaws.com/cats-kittens/nutrition/what-can-cats-eat/foods-toxic-to-cats
7. Purina. (n.d.). Harmful substances and poisonous foods for cats. https://www.purina.co.uk/cats/health-and-nutrition/what-not-to-feed/harmful-foods-and-substances
8. Falls Village Veterinary Hospital. (n.d.). 4 household foods toxic to dogs and cats. https://raleighncvet.com/illness-disease/4-foods-toxic-to-dogs-cats/