Can dogs eat tuna?
Short answer
Yes, tuna packed in water can be an occasional treat for dogs in small amounts, but because of its mercury and salt content it shouldn't become a regular part of the diet.
Canned tuna is a popular treat with dogs, but as a large predatory fish it accumulates mercury in its flesh. Here's how often and how much tuna is safe to feed, and which type to choose.
Why only in moderation
Tuna is a rich source of protein and omega-3 fatty acids, which makes it appealing as a nutritious treat or a flavour boost on a lick mat. In small, occasional amounts it isn't a problem for a healthy dog.
As a large predatory fish near the top of the food chain, though, tuna accumulates methylmercury from its environment in its flesh, more so than smaller fish. An occasional spoonful won't cause harm, but feeding tuna several times a week raises the risk of long-term mercury build-up, especially in small dogs.
Canned tuna is also usually packed in brine or oil, and neither is ideal for dogs. Oil adds extra fat, which can cause digestive upset or contribute to pancreatitis, while a salty brine puts strain on the kidneys and increases thirst.
Raw tuna, such as from sushi, isn't recommended for the same reasons as other raw fish: a risk of parasites and bacterial contamination, plus no guarantee of freshness or sourcing.
How to serve tuna
- Choose tuna packed in water or its own juice, not oil or a salty brine.
- Drain the liquid before serving and rinse the fish to reduce its salt content.
- Offer only a small amount as an addition to a normal diet, not as a regular substitute for meat.
- Avoid flavoured varieties with herbs, onion or other seasoning.
Rough portion
Small dog: a teaspoon, occasionally. Medium dog: a tablespoon. Large dog: two tablespoons. No more than once every one to two weeks, not as a regular part of the diet.
Risks
- Gradual mercury build-up in the body with regular feeding, especially in small breeds.
- High salt content in the brine, which strains the kidneys and increases thirst.
- Digestive upset from tuna packed in oil.
- Risk of bacterial or parasitic infection from raw tuna.
Symptoms to watch for
- Vomiting, diarrhoea after a fatty or salty tin
- Increased thirst and urination
- With chronic mercury exposure: trembling, uncoordinated movement, lethargy (rare, only with long-term excessive intake)
Your dog already ate tuna. What now?
- If your dog ate a whole tin of tuna, watch it for 24 hours for vomiting or diarrhoea, especially if it was tuna in oil or brine.
- Make sure your dog has plenty of fresh water available because of the extra salt intake.
- A one-off larger serving usually isn't an acute mercury risk, but cut back on how often you offer it going forward.
Common questions about dogs and tuna
How much tuna can a dog eat?
A small amount, roughly a teaspoon up to two tablespoons depending on the dog's size, once every one to two weeks, is fine. Feeding it more often raises the risk of long-term mercury build-up and excess salt from the brine.
Is tuna in water safe for dogs?
Yes, it's a safer choice than tuna packed in oil or a salty brine. Even so, it should stay an occasional treat because of its mercury content, not a regular part of the diet.
Can dogs eat canned tuna regularly?
It's not recommended. As a large predatory fish, tuna contains more mercury than smaller fish, and feeding it regularly could lead to it building up in the body. It's better to rotate it with other fish, such as cod or salmon.
Is raw tuna dangerous for dogs?
It isn't recommended, because raw fish in general carries a risk of parasites and bacterial contamination, and it lacks the assurance of freshness and sourcing that sushi-grade fish for human consumption has. A cooked or canned version is always the safer option.
Is tuna oil a good supplement for dogs?
A quality fish oil made specifically for dogs is a better choice than oil drained from a tin, since it has a known dosage and a lower risk of going rancid. Oil from canned tuna just adds unnecessary fat and can upset digestion, so it's best avoided as a supplement.
Other good treats
Can dogs eat eggs?
Yes, eggs are an excellent source of protein and biotin for dogs, ideally boiled or scrambled without salt or fat. Raw eggs aren't recommended because of the risk of salmonella and reduced biotin absorption.
Can dogs eat fish?
Yes, well-cooked, boneless fish is a healthy source of protein and omega-3 fatty acids for dogs. Raw fish and fish bones are not recommended, though, because of the risk of parasites, thiamine deficiency, and injury to the digestive tract.
Can dogs eat chicken?
Yes, cooked chicken with no skin, bones, or seasoning is one of the best and most digestible protein sources for dogs. Vets commonly recommend it as part of a bland diet for stomach upset too.
Can dogs eat salmon?
Yes, well-cooked, boneless salmon is a healthy source of omega-3 fatty acids for dogs, but raw or smoked salmon should never be fed because of the risk of a serious infection and its high salt content.
More from meat and fish
Can dogs eat beef?
Yes, cooked or stewed lean beef is an excellent source of protein for dogs and is one of the most common ingredients in both homemade and commercial dog food. Just avoid fatty cuts, seasoning, and the risks that come with raw meat.
Can dogs eat cooked bones?
No, don't give dogs cooked bones of any kind, whether from chicken, turkey, pork or beef. Cooking makes bones brittle, so they easily splinter into sharp fragments that can injure the oesophagus, stomach or intestines and even cause a fatal blockage.
Can dogs eat chicken bones?
Yes, but only raw chicken bones of an appropriate size, never cooked. Cooked bones splinter into sharp shards that can pierce the throat or gut. Even raw bones carry a choking or injury risk, so always supervise your dog while feeding them.
Sources
- AKC: Can Dogs Eat Tuna?
- FDA/EPA: Advice about Eating Fish, mercury levels
Last updated 2 September 2026.