Can Cats and Dogs Eat Canned Tuna?
General information only — not veterinary advice. Every pet is different. If you are worried about your own pet, talk to your veterinarian.
The short answer: A small amount of plain canned tuna, now and then, is a treat — not a meal — for both cats and dogs. Tuna is not a poison for cats or dogs the way onions or chocolate are. The problems come from too much, too often: tuna does not have all the nutrients a cat or dog needs, and tuna can carry mercury, which builds up in the body over time.
Mercury charts made for people are not made for pets. Cats and dogs are much smaller than people, and dogs, the AKC notes, process substances differently than humans do — so use pet guidance, like the guidance on this page, not human food rules.
Cats and canned tuna
Yes — as a small, occasional treat. An occasional bite of plain, human-grade tuna is safe for a cat, but it should not be a regular part of the diet. Tuna lacks essential nutrients cats need, and too much can lead to mercury poisoning.
How much, and how often?
PetMD, in guidance written by a veterinarian, gives this cautious limit for human-grade tuna: no more than 1 tablespoon of plain, unseasoned, cooked tuna, once a week. Treats in general should be a small part of the diet — the ASPCA says treats should be no more than 5–10% of a cat's diet, and Tufts University's Cummings School of Veterinary Medicine says pets should get only 10% of their daily calories from treats so the diet stays balanced.
Kittens
PetMD says kittens should not eat tuna, and it is best to wait until a cat is at least 1 year old before offering treats like tuna. Kittens are more sensitive to changes in their diet and to toxins such as mercury.
Why tuna must not become the meal
- It is not complete food. Tuna made for people is not balanced for cats. Human-grade tuna is low in vitamin E, a vitamin cats need, and feeding large amounts can cause disease. Cats also need taurine, an essential amino acid for heart and eye health; properly balanced cat foods contain it.
- Mercury adds up. Tuna is high in mercury, especially albacore (“white”) tuna. Cats fed lots of tuna can develop mercury toxicity. The Merck Veterinary Manual notes that commercial fish-based dietary products have been linked to chronic mercury poisoning in cats.
- Too much can add weight. Tuna is rich in calories, and too much can lead to obesity rather quickly.
- Some cats are allergic to fish. A new food can disagree with some cats.
Tuna made specifically for cats is different: it is supplemented with extra ingredients to make it more balanced. This page is about the canned tuna made for people.
Dogs and canned tuna
Yes — but only small amounts, and only now and then. The American Kennel Club (AKC) puts it this way: tuna is not innately toxic to dogs the way onions or chocolate are — but eating tuna can still pose risks because of the mercury it can contain.
How much, and how often?
The AKC does not give a set amount. It says that if you feed canned tuna, feed only small amounts, occasionally. What is unsafe, the AKC says, is feeding tuna regularly, which can lead to mercury poisoning over time. Treats in general should stay small: Tufts University's Cummings School of Veterinary Medicine says a pet should receive only 10% of its daily calories from treats so the diet is not unbalanced. If your dog sneaks a small bit of tuna, that alone is not a reason to panic — a tiny amount will not cause mercury poisoning.
Why tuna must not become the meal
- Mercury adds up. Fresh tuna has much higher mercury levels than some other fish, such as salmon and tilapia. Eating too much mercury can result in mercury poisoning, which can cause severe — or potentially fatal — health problems.
- Dogs are smaller than people. Because dogs are smaller and process substances differently than humans, they are more sensitive to mercury, particularly if tuna is eaten regularly.
- It is not complete food. A dog's regular, balanced dog food should stay the main diet. Tuna is a treat, not a replacement for it.
If you want to share fish with your dog, the AKC says the safest fresh fish are the ones most commonly used in commercial dog food, such as whitefish, herring, flounder, and Arctic char.
Packed in water, or packed in oil?
Choose water-packed. Skip oil-packed. This is the clear guidance for both cats and dogs:
- For cats: PetMD says canned tuna is safe to feed a cat if it is packed in water, not oil — and it should have no spices or other flavorings added.
- For dogs: The AKC says canned tuna often contains added salt or is packed in oil, and neither is healthy for a dog. If you feed a small amount occasionally, look for “light” (skipjack) tuna packed only in water, with no added salt or seasonings.
- “White” tuna means albacore. For both cats and dogs, albacore is the higher-mercury choice and is best avoided. “Light” skipjack is the lower-mercury canned choice.
- Plain only. Do not share tuna salad, seasoned tuna, or tuna mixed with onion or garlic. The ASPCA warns that onion, garlic, and chives can cause stomach irritation and red blood cell damage; cats are more susceptible, and dogs are also at risk. The ASPCA also warns that very salty foods can cause increased thirst and urination, and that fats and oils can cause vomiting and diarrhea and, in some pets, pancreatitis.
Treat, not a meal — the simple rule
- Keep the pet's regular, complete pet food as the meal. That food is made to be balanced.
- Keep all treats — tuna included — to no more than about 10% of the day's calories (5–10% for cats, per the ASPCA).
- Plain, water-packed, unseasoned tuna only. No oil, no added salt, no spices, no onion or garlic.
- For cats, PetMD's cautious limit is 1 tablespoon, once a week, for human-grade tuna — and no tuna for kittens under 1 year old.
- For dogs, there is no official set amount: small amounts, occasionally, is the guidance. Regular feeding is the problem.
- Talk to your veterinarian before adding a new food if your pet has a medical condition — treats that are fine for a healthy pet may not suit a pet with health issues.
When to call a vet
Call your veterinarian promptly — do not wait and watch — if:
- Your pet has been fed tuna regularly, especially albacore or other high-mercury tuna, and shows any of the warning signs below.
- Dogs: the AKC lists possible signs of mercury poisoning in dogs that mean “take them to the vet immediately,” including loss of coordination, tremors, loss of vision, anxiety or nervousness, hair loss, loss of feeling in the paws, vomiting blood, watery diarrhea or blood in the stool, and kidney damage signs such as inability to urinate or abdominal swelling.
- Cats and dogs: the Merck Veterinary Manual lists common signs of organic mercury poisoning that include blindness, wobbliness (ataxia) and poor coordination, tremors, abnormal behavior, and seizures; advanced cases can include depression, loss of appetite, and paralysis.
- Cats: the ASPCA says to take your cat to the veterinarian if not eating, diarrhea, vomiting, or lethargy continue for more than two days.
- You think your pet ate something poisonous. The ASPCA advises noting the amount eaten and contacting your veterinarian or ASPCA Poison Control.
ASPCA Animal Poison Control Center: (888) 426-4435. This number is listed on the ASPCA's pet-care pages. If you suspect your pet has eaten a poisonous substance, the ASPCA says to call your veterinarian or this center for 24-hour animal poison information.
A single small taste of plain tuna is not, by itself, listed by these sources as an emergency. Feeding tuna often, feeding a lot at once, or any of the signs above are the reasons to call.
Sources
Facts on this page were checked against these sources:
- ASPCA — “People Foods to Avoid Feeding Your Pets” (ASPCA Animal Poison Control): poison-control number, onion/garlic/chives, salt, and fats-and-oils warnings.
- ASPCA — “General Cat Care”: treats no more than 5–10% of a cat's diet; cats require taurine; when to take a cat to the veterinarian; poison-control number.
- American Kennel Club (AKC) — “Can Dogs Eat Tuna?”: tuna and dogs, mercury, albacore, water-packed light tuna, signs of mercury poisoning in dogs, and safer fish.
- PetMD — “Can Cats Eat Tuna?” (Sandra C. Mitchell, DVM, DABVP): tuna and cats, water-packed not oil, albacore mercury, vitamin E, kittens, and the 1-tablespoon once-a-week limit.
- Merck Veterinary Manual — “Mercury Toxicosis in Animals”: fish-based diets and chronic mercury poisoning in cats, and signs of organic mercury poisoning.
- Tufts University, Cummings School of Veterinary Medicine (Petfoodology) — “Treat Options for Dogs and Cats Without Unbalancing Their Diet”: treats should be only 10% of a pet's daily calories.
Checked November 2026.
General information only — not veterinary advice. This page does not diagnose your pet. For advice about your own cat or dog, talk to your veterinarian. ASPCA Animal Poison Control Center: (888) 426-4435.