Can dogs eat tuna?

Written by Dr Andrew Miller MRCVSDr Andrew Miller MRCVS is an expert veterinary working in the field for over 10 years after graduating from Bristol University. Andy fact checks and writes for Pure Pet Food while also working as a full time veterinarian. Pure Pet FoodPure Pet Food are the experts in healthy dog food and healthy dogs featured in media outlets such as BBC, Good Housekeeping and The Telegraph. Working with high profile veterinary professionals and nutritionists, Pure Pet Food are changing dog food for the better. - Our editorial process

We all know eating fresh fish is an important part of a healthy diet, and many of us humans don’t eat enough fish. The same is true for many dogs, as the digestible protein, omega-3, and nutrients found in fish are fantastic for keeping our pups happy and healthy.

To make sure your pooch is eating plenty of fish, you can introduce seafood snacks to supplement their diet, such as dried sprats as a tasty and healthy alternative to dog treats, or occasionally mixing a little fish in with their dinner. But what fish is safe and healthy for your dog to eat?

Many of us will have cans of tuna or sardines at home. Since tuna is one of the most commonly eaten fish, it makes sense to wonder if our dogs can eat tuna too. Tinned tuna is convenient and cost-effective, making it tempting to offer to our pets. But can dogs eat tuna?

Can dogs eat tuna?

Tuna is safe to eat in small amounts as a rare treat, but it definitely shouldn’t become a staple food for your furry friend. Like many fish, tuna is a good source of protein and omega-3 which are essential in your dog’s diet to keep them healthy.

However, your dog should not eat tuna regularly or in large amounts because it is also a source of mercury. Eating too much tuna will lead to a build-up of mercury over time, which can then cause long-term health problems. Mackerel is a fish that also contains mercury, but not so much as tuna.

Some commercial dog foods do contain tuna as an ingredient. While this proves it is safe for your pooch to eat, it’s advised not to feed them tuna regularly to avoid the accumulation of mercury. If you want your pup to benefit from having fish as a regular part of their diet, opt for dog food containing fresh, short-lived fish with lower mercury levels.

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Additionally, whether your dog can eat tuna or not will depend on the kind of tuna you are offering. Even canned tuna can come in brine, springwater, or oil, and these methods of preservation have different caveats for your canine companion.

Not to mention, there are a number of different species of tuna swimming in our seas. So what kinds of tuna can your pup eat?

Can dogs eat canned tuna?

Canned tuna is a cheap and easy way for us to introduce fish into our diets, and most of us will have a can in our cupboard somewhere. But can we share tinned tuna chunks with our dogs?

Firstly, canned tuna is often meat from Albacore or Skipjack species of tuna. Of the two, Skipjack is the safer option for your pooch as it has lower levels of mercury.

However, canned tuna is often high in salt which isn’t good for our furry friends. You can find cans with no added salt though, and these are a better choice if you’re planning to share the fish with your pup.

Some canned tuna is cooked or “infused” with herbs and spices. While it might make them especially tasty for humans and great on salads, you should never feed your dog any tinned tuna that has additional seasonings and spices because they can cause illness.

Beyond the species, spices, and salt, canned tuna is also preserved in different liquids. You’ll find chunks in brine, sunflower oil, or freshwater, but which is safe for canine consumption?

Can dogs eat tuna in brine?

Although a very small amount of tuna in brine shouldn’t be toxic, it’s best to avoid feeding it to your pooch. As you could probably guess, it contains a lot of salt which is bad for dogs and ingesting too much can cause sodium poisoning.

Tuna canned with sunflower oil is a little safer, but the best choice is by far tuna canned in spring water as it has less salt and fat compared to other kinds of canned tuna.

Can dogs eat tuna in sunflower oil?

If you drain the fish thoroughly, it is safe to let your pooch eat a little tuna that was canned in oil. Sunflower oil is lower in saturated fat than other oils and can even offer some benefits for your dog’s fur if they eat a little.

However, consuming too much of any oil can contribute to unhealthy weight gain and inflammation. Sunflower oil contains omega-6 which is great for your dog’s health, but it must be ingested in conjunction with omega-3 to prevent inflammation and unwanted immune responses.

While eating a little tuna in sunflower oil is safe for your dog, the best choice is tuna canned in spring water.

Can dogs eat tuna steak?

Tuna steak is a tricky subject. Human connoisseurs will insist that bluefin is best, and we even eat our tuna raw in sushi and sashimi. But you should never let your pup eat tuna raw as it may carry parasites and is more likely to cause gastrointestinal upset compared to cooked fish. Additionally, you should never feed your dog bluefin tuna as it contains high mercury levels.

However, if your tuna steak is from species with lower mercury levels, such as Albacore or Skipjack, you can safely offer some to your pooch. These varieties are often used in canned tuna steak. If you want to offer your dog some fresh tuna steak, make sure it is cooked and served plain.

What species of tuna can your dog eat?

In general, your dog can eat any of the species of tuna we humans eat. However, the different species vary greatly in their size and lifespan, which has an impact on the levels of mercury in their tissue.

Mercury in tuna

Lots of our rubbish and pollutants end up in the oceans. Heavy metals such as mercury and lead enter our seas through erosion, rain, rivers, and human pollution and accumulate inside the tissues of the creatures that call the ocean home.

The longer a fish’s lifetime the more of these heavy metals build up inside of them. This is because they ingest a small amount of mercury with every meal, which then cannot be destroyed.

Tuna is a large and long-lived fish so it contains higher levels of mercury than other species. It spends longer living in the ocean eating lots of other smaller fish, including the mercury inside those other fish. Some species of tuna have different levels of mercury. For example, skipjack tuna is relatively small and contains three times less mercury than larger species like Albacore.

Whenever you or your pooch eat some tuna, a little mercury is introduced into your diet. In the long-run, this isn’t a huge problem. However, if you or your pooch eat too much tuna in a short period of time, you will ingest too much mercury and could become poisoned.

If your pup shows any signs of poisoning after eating, such as tremors and excessive drooling, visit your vet immediately.

To avoid the risk of mercury poisoning it’s best to feed tuna in moderation. If you are concerned about mercury in your dog’s diet, try feeding them other kinds of fish like salmon or white fish. These fish offer the same nutritional benefits but have much lower levels of mercury and so don’t pose the same risk as tuna.

How much tuna can I give my dog?

Tuna is safe when fed in moderation, but do not feed your dog tuna regularly as it will contribute to the accumulation of mercury in your pooch’s tissues.

Keep any tuna your dog eats to a small amount, as little as one tablespoon, and do not feed them tuna every day. When introducing tuna or any other new food to your dog, feed them a small amount and monitor them for any signs of illness.

If you have a large dog, never feed them more than a can of tuna over the course of a week, and do not give them a can of tuna every week. Smaller dogs have a lower tolerance and so should eat even less, as little as half a can over a week. Regardless of the size of your dog, never let them eat a whole can of tuna in one sitting.

If you do feed your dog some tuna, don’t feed them any more for a few weeks. Larger dogs can eat tuna again sooner than smaller breeds, but most owners err on the side of caution and prefer to keep tuna as a special treat.

To stay safe, avoid feeding your dog tuna regularly. A spoonful of tuna in their dinner every couple of weeks shouldn’t cause any harm. So if you are making yourself a tuna sandwich or a pasta bake, you can save a spoonful of fish to treat your pup with. You can also treat your dog to cod, salmon and mackerel too!

Recap: Can dogs eat tuna?

Yes, dogs can eat a small amount of tuna. The best kind to offer your pup is tuna canned in spring water. However, you should never feed your dog tuna regularly to prevent them from ingesting large quantities of mercury.

Salmon is a fish that is a much better fish to feed your dog, if you're wanting to treat them to some fishy food. Salmon is a protein source that is included in some of our Pure recipes, and it has many functional benefits.

It aids growth and development, it's rich in omega 3 to aid digestion and reduce inflammation and it is high in vitamins and antioxidants to ensure your pup is as healthy as can be.