Fresh and canned tuna are frequent ingredients we use in our daily cooking. The smell is enticing, and we know it can be a healthy food for us. If your dog stands next to you with their big eyes whenever you prepare food at the counter, you might wonder if it is ok to share some tuna with your pup. While tuna is a healthy choice for us and does have some health benefits for your dog, it also carries a number of risks that other fish does not. These health risks outweigh any nutritional benefits dogs can get from eating tuna.
It isn’t a terrible problem if dogs eat some tuna that has fallen on the floor, and you could think of a little taste of tuna as a once-in-a-while treat, but it should not be one of the ‘people foods’ that you share with your dog.
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Vitamins and minerals
Tuna contains a number of important vitamins and minerals. It is low in fat and is a good source of protein and omega-3 fatty acids. These healthful fatty acids help give your dog a shiny coat, healthy skin, and strong joints. Tuna has a lot of vitamin B12, which works to prevent disease and boost immunity, selenium that is essential for the immune system and thyroid function, and niacin (vitamin B3), which helps with digestion, supports important brain function, and aids the body in converting food to energy.
Despite these health supporting vitamins and minerals, your dog is much better off eating a well-balanced prepared dog food to ensure they are getting the optimal combination of necessary nutrients every day. The amount of tuna your dog would have to eat in order to satisfy their daily requirements of these nutrients would cause them to ingest harmful levels of mercury and other toxins contained in tuna.
There are a number of other fish, such as sardines, salmon, and whitefish that offer these health benefits without the risks that come from tuna.
The primary problem with dogs eating tuna is that it contains a large amount of mercury, which can lead to mercury poisoning in dogs. Mercury is a naturally occurring element in the Earth’s crust. It is released into the environment through various disturbances like volcanic eruptions, the weathering of rocks that contain mercury, and human activities such as coal-burning power plants and waste incinerators, mining, and using coal for cooking and heating. Once mercury is in the environment it bioaccumulates in fish and shellfish. This means that they contain more mercury than their surroundings. Mercury is also a biomagnifier, meaning that large fish who consume a lot of smaller fish have much higher concentrations of mercury. Because tuna can weigh around 200 pounds at 10 years old, they are large reservoirs of mercury. Fresh tuna contains higher levels of mercury than cooked and canned tuna and should not be given to dogs.
When we eat large fish such as tuna that are very high in mercury, we also ingest high levels of it, and it is recommended to only have 1-2 servings per week. As our dogs are smaller than we are, they would be more impacted by these elevated mercury levels. Small dogs and especially puppies who are still developing should not have any tuna at all.
There are a few other potential issues to be aware of if a dog eats tuna:
- They might choke on the small bones present in fresh tuna.
- They could also have an allergic reaction. Certain breeds, such as Labrador Retrievers, cocker spaniels, and West Highland Terriers, are more prone to food allergies and might have a response that could range from stomach upset to hives and itchiness to some dogs even having an anaphylactic response to tuna.
- Some varieties of canned tuna also contain high levels of sodium, which can lead to vomiting, diarrhea, excessive thirst and increased urination. Some canned tuna also includes spices and other seasonings that might not agree with your dog or that could be harmful such as onion.
- Tuna packed in oil can be harmful for your dog as it can lead to pancreatitis. Pancreatitis is a condition where the pancreas becomes inflamed, leading to nausea, vomiting, pain, lethargy, or fever. It can be caused by ingesting too much high fat food, such as oil.
Mercury exposure can be the cause of a serious health problem for dogs – mercury poisoning. Again, this risk is from ingesting a larger amount of tuna or having it more frequently so the mercury can biomagnify, and is not typically the result of a single time eating tuna.
If you also have a cat, be careful that your dog does not eat the cat’s food, because many cat foods contain tuna, and the amount that your dog will eat could give them too much mercury.
Signs of mercury poisoning after eating tuna may include:
- Difficulty walking
- Agitation or nervousness
- Hair loss
- Kidney damage
These symptoms can indicate that your dog has had too much tuna and the mercury buildup is impacting their various systems. Contact your veterinarian to have your dog seen immediately. Quick treatment can limit the long-term effects of mercury poisoning and give the best chances for a full recovery. Treatment might include IV hydration and anti-nausea medications if your dog has been vomiting or having diarrhea. In severe cases, the dog might need dialysis to remove mercury from their kidneys or a treatment of activated charcoal to bind with the mercury and help remove it from the dog’s system.
The bottom line
Since tuna itself is not toxic to dogs, they should be fine if they have snatched a small amount. After eating a whole can of tuna, dogs might have an upset stomach leading to vomiting or diarrhea, but should be fine once it passes through their system. The largest caution is around the accumulation of mercury either through eating a large amount or having tuna frequently.
Outside of your dog’s nutritionally balanced high-quality food, there are plenty of good tasting, beneficial snacks you can offer from time to time. Tuna should not be one of them.