Can Dogs Eat Tuna?

A little plain tuna now and then is fine for most dogs. It is high in protein and most dogs love it. The reason to keep it occasional is mercury: tuna are large, long-lived fish that build up more of it than most seafood, and it accumulates in a dog the same way it does in a person. Choose tuna canned in water with no salt added, and keep it to a small treat.

The Version That Is Fine

Canned light tuna in water, drained, with no added salt. Or a plain cooked tuna steak with no seasoning. A tablespoon of drained canned tuna is about 15 to 20 calories and mostly protein.

Which Tuna

The Mercury Question

Mercury enters the ocean food chain and concentrates as big fish eat smaller ones, so long-lived predators like tuna, swordfish and king mackerel carry the most. In dogs, as in people, very high exposure over time can harm the nervous system and kidneys. Signs of mercury poisoning in dogs include tremors, loss of coordination, vomiting, hair loss and anxiety, but they belong to large, regular amounts over a long period, not to a spoonful of tuna on a Sunday.

The practical answer is not to avoid tuna completely, just to treat it as an occasional extra, choose light over albacore, and not use it as a daily topper. If you want fish in your dog’s week, smaller fish are the better habit, as below.

How Much Tuna

Once or twice a week at most. Tuna also counts toward the 10% of daily calories that treats and extras share.

If Your Dog Ate A Whole Can

One can will not cause mercury poisoning. If it was in oil, expect a greasy stool or an upset stomach. A whole can of tuna in oil, for a small dog or one with a pancreatitis history, is worth a call to your vet. Check the lid too: dogs sometimes cut their tongues licking an open can.

What About Cat Food With Tuna?

A stolen mouthful of the cat’s tuna food will not hurt a dog. As a habit it is a poor idea: cat food is made for cats, with more protein and fat than a dog needs, and a dog that eats it regularly can put on weight or get an upset stomach. Feed the cat where the dog cannot reach.

Better Fish For Dogs

Smaller, shorter-lived fish carry far less mercury and more omega-3 fatty acids, which support skin, coat and joints. Plain cooked salmon, never raw, and sardines canned in water with no salt are both better regular choices than tuna. For a lean seafood treat, plain cooked shrimp works too.

Which Dogs Should Skip It

• Dogs with a fish allergy, or on an elimination diet.
• Dogs with kidney disease on a phosphorus or protein restricted diet, unless your vet says otherwise.
• Dogs on a low sodium diet, unless the tuna has no added salt.
• Pregnant dogs and young puppies, who are more sensitive to mercury.

Fish is also a common protein in dog food. Foods made with whole fish or fish meal from smaller species give the benefits without the mercury concern of a tuna-heavy diet. For any other food question, check the food checker.