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Mercury levels in canned tuna cat food.

Species: Cat
Breed: Persian
Age: 2-5 years
My cat eats a lot of tuna flavored canned cat food. I have heard that mercury in the tuna can be a problem. What do you think about the mercury levels of fish based canned cat foods?




Online vet, Dr. Marie

Dr. Marie replied:

Hi Joan,

I can't say I have ever encountered an issue regarding mercury levels in canned cat food. So, I did some research for you to see what I could find out.

The general consensus from vets is that there is no problem with feeding tuna based cat foods. I did find some interesting articles though:

Here is an article that looked at mercury levels in tissues of cats fed mercury contaminated tuna. For 100 days they fed kittens a diet of tuna that was known to be very high in mercury. They had a control group that they fed a commercial cat food diet that contained tuna. The cats fed the contaminated diet had way higher mercury levels in their blood and organs than the cats on the regular commercial tuna diet. However, they could not see any difference in the behavior or health of the two groups.

That sort of implies that there is no problem with feeding a tunafish diet.

HOWEVER....

Check out this study:

A tuna fish diet influences cat behavior.

Here is the summary of the article:
When observed in their home cages, cats fed commercial tuna fish cat food were less active, vocalized less, and spent more time on the floor and more time eating than cats fed commercial beef cat food. There were no differences in response to human handling between the two groups. There were no differences in learning ability on a two-choice point maze or in reversal learning in the same maze between beef- and tuna-fed cats. The behavior of the groups differed in a 15-min open field test only in the number of toys contacted. Cats fed the tuna had elevated tissue levels of mercury and selenium.


To me, that information seems significant. Cats on a commercial tuna fish diet had elevated tissue levels of mercury and selenium. And, those cats were less active, less meowy, more lazy and ate more.

If I had a cat who loved a canned tuna cat food I would likely give it to him once or twice a week, but I would not want to feed it as the only part of his diet.

Dr. Marie.



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Dr. MarieDr. Marie is a veterinarian who practices in a busy animal hospital in Ottawa, Ontario. She created Ask A Vet Question as a resource for good, accurate veterinary advice online. Dr. Marie treats dogs, cats, hamsters, guinea pigs, and rats. She has been a vet since 1999.

Is an online vet visit just as good as a trip to your veterinarian? No! But, many times, asking an online veterinarian a question can help save you money. While Dr. Marie can't officially diagnose your pet or prescribe medications, she can often advise you on whether a vet visit is necessary. You can also ask Dr. Marie for a second opinion on your pet's condition.