Cat food safety: what cats can and can't eat

Cats are not small dogs, and the list that matters for them is different. Their size, their liver chemistry and their grooming habit all make small exposures serious.

Lilies — the most dangerous plant in a cat's home

True lilies and daylilies cause acute kidney failure in cats, and every part is toxic: petals, leaves, stem, pollen and the water in the vase. A cat that brushes past a bouquet, gets pollen on its coat and grooms it off has taken a potentially fatal dose without eating anything. There is no known safe exposure and treatment is time-critical, so a lily in the house is worth removing rather than managing.

Lilies

Paracetamol and other human painkillers

Cats lack an enzyme pathway that people rely on to process paracetamol, which makes them extraordinarily sensitive — a single standard tablet can kill an average cat. Ibuprofen and aspirin are dangerous too. Never give a cat human medicine, and never assume that a dose scaled down by weight is safe, because the problem is the pathway rather than the amount.

Acetaminophen · Ibuprofen

Onions, garlic, chives and leeks

Cats are more sensitive to these than dogs are. They destroy red blood cells and cause haemolytic anaemia, the effect builds up over repeated small exposures, and cooking or drying does not help. The usual route is not a raw onion but seasoned human food, baby food, stock and garlic supplements sold for pets.

Onions · Garlic

Dog food, as a diet rather than a mouthful

A stolen mouthful is not an emergency, but a cat fed on dog food will become ill. Cats are obligate carnivores and cannot make enough taurine, arachidonic acid or preformed vitamin A for themselves, and dog food is not formulated to supply them. Sustained taurine deficiency causes dilated cardiomyopathy and irreversible retinal degeneration.

Raw fish as a staple, and tuna-only diets

Some raw fish contains thiaminase, an enzyme that destroys vitamin B1, and a diet built on it causes thiamine deficiency with neurological signs. Tinned tuna meant for people is a separate problem: it is not nutritionally complete, it is high in mercury and unsaturated fat, and cats that hold out for it often start refusing balanced food.

Chocolate, coffee and energy drinks

The theobromine and caffeine problem is the same as in dogs, and per kilogram cats are more sensitive. Cats are less inclined to eat chocolate, so poisonings are rarer, but a 4 kg animal needs a much smaller amount to reach the same dose, and milk-based chocolate drinks are more tempting than a bar.

Chocolate · Coffee

Alcohol and raw yeast dough

Small cats and ethanol are a bad combination, and the quantities involved are trivial — a few laps of a spilled drink, or the liqueur in a dessert. Raw dough keeps fermenting in a warm stomach, producing alcohol and swelling as it goes.

Alcohol · Raw Yeast Dough

Grapes, raisins and xylitol

Both are well documented in dogs and much less studied in cats, largely because cats rarely eat sweet things. There is no evidence of a safe dose in cats either, so both belong on the avoid list: grapes and raisins for the kidney risk, xylitol for the insulin crash.

Grapes · Xylitol

A cat's diet should be built on complete cat food. Everything below is a treat or a functional extra rather than a replacement for it.

Plain cooked meat and poultry

Cooked chicken, turkey and lean beef, unseasoned and off the bone, make the ideal cat treat: high in protein, no carbohydrate, and close to what a cat would actually hunt. Skip the skin and any pan juices, which carry salt, oil and often onion or garlic.

Cooked white fish, and a little oily fish

Cooked cod, haddock, plain salmon and a small amount of sardine in spring water are safe and popular. Serve them cooked and boneless, and keep fish occasional rather than routine, because fish-heavy diets skew the nutrient balance.

Cooked egg

Scrambled without butter or salt, or hard boiled, egg is a well-tolerated source of protein and taurine. Raw egg white is not, because avidin binds biotin, and raw egg carries the usual bacterial risk.

Plain pumpkin and a few vegetables

A teaspoon of plain cooked pumpkin is the standard suggestion for mild constipation or loose stools, and small amounts of cooked carrot, green beans or peas are harmless. Cats do not need vegetables at all, so treat these as a functional extra rather than as nutrition.

Water, which matters more than any treat

The most useful thing you can add to a cat's diet is not a food. Cats have a weak thirst drive, and chronic mild dehydration underlies much of the urinary disease they get. Wet food, a fountain, and several bowls placed away from the food do more for a cat than any snack.

Keep all treats, plain meat included, under about 10% of daily calories: a cat's total energy requirement is small and easily displaced. Introduce anything new in a small amount and wait two or three days before adding another.

Advice written for dogs does not transfer to cats. These five points explain why, and cover most of what people get wrong.

A cat is an obligate carnivore, not a small dog

Cats have absolute dietary requirements — taurine, arachidonic acid, preformed vitamin A, and a higher protein floor — that dogs can work around. That is why vegetarian and vegan diets are unsafe for cats, and why it is fine for the dog is not a useful test.

Dose and body weight decide almost everything

An average cat weighs 4 to 5 kg, a fraction of most dogs, so the same mouthful of a toxic food is a far larger dose. Any figure you find quoted per animal rather than per kilogram was probably written about a dog.

Cats poison themselves by grooming

This is the difference that catches people out. A cat does not have to eat anything: pollen on the coat, a spill walked through, a flea treatment meant for a dog, or a drop of essential oil all get swallowed at the next wash. Contamination of the fur is an ingestion event.

Sudden fussiness is a symptom, not a preference

Cats hide illness well, and a cat that stops eating is in trouble faster than other pets: much beyond 24 hours without food risks hepatic lipidosis, a liver condition that is dangerous in its own right. Do not wait out a hunger strike.

Check the label before you assume it belongs in the house

Many cat poisonings involve things that are not food at all: permethrin flea treatments meant for dogs, essential oils and diffusers, antifreeze, and lily bouquets. If you are unsure, look it up before it comes into the room.

Act on the suspicion rather than on symptoms. Cats mask illness, and with lilies and paracetamol the treatable window closes long before a cat looks unwell.

Do this first

• Take the rest away and shut your cat in one room where you can see them.
• If the substance is on their coat, stop them grooming. An Elizabethan collar or a loose towel wrap buys time.
• Work out what, how much and when, and note your cat's weight.
• Keep the packaging, the label, or the plant itself — identifying it changes the treatment.
• Call your vet, the out-of-hours service or a poison hotline immediately, and say that it is a cat.

Do not do this

• Do not induce vomiting. There is no safe way to do it at home in a cat, and the products used in dogs are dangerous here.
• Do not bathe a contaminated cat in anything except plain warm water with a little mild washing-up liquid, and only if you have been told to.
• Do not give any human medicine, and paracetamol least of all — it is the most common fatal mistake owners make with cats.
• Do not offer milk, oil or food to dilute the toxin.
• Do not wait to see whether your cat becomes unwell.

Signs that mean go now

• Drooling, foaming, or pawing at the mouth
• Vomiting or retching, especially repeatedly
• Hiding, sitting hunched, or a sudden change in temperament
• Not eating for more than 24 hours, or not drinking
• Straining in the litter tray, or passing no urine
• Wobbliness, twitching, tremors or seizures
• Fast, open-mouthed or laboured breathing — always an emergency in a cat
• Pale, white, yellow or muddy gums