Don't feed fish to your cats and dogs!

Last November, I posted a warning about made-in-China chicken jerky treats that are killing our dogs. Now, here’s another word-of-caution.
If you love your cats and dogs, don’t feed them fish — excepting sardines and salmon — because they’re loaded with toxic metals like mercury. In this video, veterinarian Dr. Karen Becker explains why.

Here are the reasons for not feeding fish to our pets:

1. Many types of fish are contaminated with toxic metals like mercury, industrial chemicals like PCBs and dioxins, and pesticides like DDT.
These toxins are absorbed by the smallest ocean plants and animals at the low end of the food chain. As larger ocean dwellers come along and consume these contaminated plants and prey, the toxins accumulate and become more concentrated in the bodies of the bigger fish. This includes tuna, which many people regularly feed their cats and some dogs.
2. Pet food containing fish has a potentially deadly preservative, ethoxyquin.
The fish in pet food is heavily preserved during the manufacturing process using a chemical preservative called ethoxyquin, which is known to be a cancer-causing agent. Ethoxyquin is banned from use in human food except in very small quantities allowed as preservatives in spices.
Dr. Becker had experienced first-hand the heartache of ethoxyquin poisoning with her Rottweiler, Gemini. When Becker was in her sophomore year of vet school, 7-year-old Gemini went into liver failure after consuming food containing ethoxyquin. Becker got the food for free from a major pet food manufacturer who was giving away the stuff to vet students. It was then and there that Becker committed herself not to feed processed pet food ever again and began her quest for clean, healthy, pure foods in the pet food supply chain.
Unfortunately, ethoxyquin is still being used in many pet foods currently available on the market. It is used to preserve the fat in almost all fish meals – fat that is made from waste products.
If the label on the pet food doesn’t list exact ingredients, including the exact meat source, you have absolutely no idea what’s in that food. And because ethoxyquin is added before the raw ingredients are shipped to the pet food manufacturers, it doesn’t get listed or disclosed on the product label. In other words, the pet food company you purchase your cat’s or dog’s food from may not be adding ethoxyquin, but that doesn’t mean it isn’t in the fish meal in that food.
Don’t make the mistake of assuming if the fish meal product label doesn’t list ethoxyquin, it’s not in there. Unless the label specifically states the formula is ethoxyquin-free, or you call the manufacturer’s 1-800 number and are told it’s not in the raw materials they purchase nor added during their own manufacturing process, you should assume the formula contains ethoxyquin.
Fish meal also happens to be one of the main pet food ingredients also contaminated with mycotoxins.
3. Fish is not the natural food of cats.
While our cats seem to love seafood meals, fish was not the natural diet of cats’ ancient ancestors who came from the deserts of Africa. Cats’ natural prey are small furry land dwellers like mice. But even though the natural diet of cats isn’t seafood, they can get addicted to fish. In fact, kitties tend to become addicted to any protein they consume exclusively. Pet food companies are acutely aware of this phenomenon, which is why most cat food formulas are either fish or chicken based. These are the proteins cats most often form addictions to.
4. Fish is one of the most highly allergenic foods for cats.
We need to rotate proteins in our pet’s diet because any food that is over-consumed can create an allergy over time. Alas, it turns out fish is one of the most highly allergenic foods for felines. Allergies cause systemic inflammation. Cats that eat allergenic foods over and over can end up with lung inflammation that can also lead to asthma,  one of the more commonly diagnosed inflammatory conditions in cats. There also appears to be a link between asthma and two contaminants found in fish — mercury and ethoxyquin.
5. Other effects from long-term ingestion of fish

  • Fish fed in high amounts can also lead to thiamine deficiency, which can cause loss of appetite, seizures, and even death.
  • Long-term ingestion of fish in cat food can also deplete vitamin E resources. Vitamin E deficiency can also cause a really painful condition called steatitis, which is yellow fat disease. If left untreated, steatitis can also be life-threatening.
  • Seafood is a very rich source of iodine, but cats aren’t designed to process a lot of iodine. Many animal nutritionists, including me, believe there’s a link between cats consuming too many iodine-rich foods and hyperthyroidism. There’s also been a link established between pop-top cans or canned cat food and hyperthyroidism.
  • The magnesium content in fish has been linked to urinary tract diseases in cats because a diet overloaded with the mineral magnesium can predispose your kitty to magnesium ammonium phosphate crystals, also known as MAP crystals or struvite crystals. Crystals are a big problem for many, many cats.

Is There Any Safe Fish to Feed Pets?

Fish are a rich source of omega-3 fatty acids, which are essential to your pet’s well-being. You can supplement your pet’s diet with certain fish:

  • Sardines packed in water. Sardines don’t live long enough to store toxins in their bodies, and they’re a terrific source of omega-3s.
  • Wild caught salmon.

If you choose not to feed any fish to your pet, Dr. Becker recommends adding krill oil or another omega-3 fatty acid to their food.

H/t our beloved Joseph!

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0 responses to “Don't feed fish to your cats and dogs!

  1. Good advice! Thanks for the tip

  2. And for people who fish for salmon in the Pacific Northwest – look up salmon poisoning. It’s deadly.

  3. Thank you Joseph and Dr. Eowyn for this most informative post. Sardines and wild-caught salmon are already on my shopping list!

  4. Dang, if it’s like this, should we be eating it either?

  5. Thanks for this information. I have two sweet cats and didin’t realize I was probably poisoning them. There are only two kinds of canned food they willl eat. Friskies, Chicken and Salmon and a couple of the the chicken ones. Theyeat Cat Naturals purina dry food too; but my vet says they need more than dry food. Can anyone give me some ideas what to feed my cats instead of these canned foods? I am sure that they are not good for them now. Maybe I should just cook them fresh chicken . They won’t eat beef or lamb. Let me know if you have some ideas for me.

  6. I received this gracious e-mail from the owner of BFF cat food:
    “Dear Dr. Eowyn,
    I have read your article titled “Don’t Feed Fish to Your Cats and Dogs”. We appreciate the efforts to better the lives and health of companion animals. We too share that mission which is why my wife and I got into the pet food business. We are founders of Weruva and Best Feline Friend (BFF) pet foods. We manufacture cat food with both land based proteins as well as fish based formulas. While we offer fish based varieties, we believe in a sound rotational diet of protein sources. If interested, we’d be more than happy to leave you some samples of our chicken and beef varieties at your local pet store.
    Maybe you’d be interested in our fish formulas as well? There is no ethoxyquin or other preservatives in any of our foods. Regarding mercury, while all fish caught in the ocean will have some mercury in them, we have chosen those that meet the FDA’s list of those lower in mercury, such as skipjack tuna (canned light tuna). This is different than other species of tuna, such as Bluefin or albacore.
    With that said, we have received a few inquiries from some concerned and confused customers who have linked the use of ethoxyquin to our foods because an image of BFF is on top of the article. The image is near the sentence that states “The fish in pet food is heavily preserved during the manufacturing process using a chemical preservative called ethoxyquin, which is known to be a cancer-causing agent”, so we understand the inquiries. Our final products do not contain preservatives, and the raw materials that we use for the fish are also not preserved and are instead brine frozen (frozen in saltwater) before processing. In that regard, we would appreciate the removal of the BFF image from the article.
    We again appreciate the efforts in improving the wellbeing of companion animals and thank you for the consideration…and if you would like some samples, please let us know!
    Best Regards,
    David Forman
    President and co-founder
    Weruva Because Weluvya!
    Fax: 646-688-6865

    I’ve removed the pic of the BFF cat food pic, and replaced it with one of my own design. My sincere apologies to BFF and the gracious David Forman!

  7. Very good source for education on pet care.

  8. Excellent post. I will be dealing with some of these issues as well..

  9. interesting email from the makers of Weruva and BFF. My 2 cats ate these 2 brands almost exclusively and mainly the fish flavors, the shrimp and rice, sardines, salmon etc. One developed hyperthyroidism and needed I-131 and it was a truly horrible year for her. My other cat developed IBD which set him up for gastric lymphoma. He is not on chemo and dying. After I began cooking all their meals, there was dramatic improvement in my female, hyper t cat but it was too late for my boy. These lines are poison. The dr is right about al of it.

    • Your email just broke my heart and crushed my spirit. HFS. I went through the same thing with a few cats. God damn the formans Wicked people to pretend to care about cats and dogs! both the canning plants they use in thailand have been given warning letters by FDA.

  10. I meant my cat IS on chemo and dying. I knew it was the food so I started searching and found this article. I had taken all the flavors of the cans to two vets and asked if they were safe, one told me he sees obese cats who have never seen a can so I shouldn’t worry and the other told me it was too dangerous to cook myself as I am not a chemist. I never felt comfortable with these foods, I should have listened to my intuition. I then asked a 3rd vet and he told me the vast majority of cans are poison and to keep cooking for my cats. I cant tell you what it is like thinking I was doing a good thing buying the expensive cans, I gave one of my cats a death sentence. I foster a cat that has been with me 2 years, he has never had anything but home cooked food. When I took him to the vet for a check-up, he kept marveling how healthy he was and asked what I was doing, I said this foster has never seen a can since I found him at 5 months, he has solid, dense lean muscle and looks like a greeting card. Stay away from these brands with the fish products. Weruva chicken looks like bleached hair and my cats refused it, I thought my cats didn’t like chicken or steak for years because of Weruva. After I started cooking, my girl loves beef most and my boy chicken.

  11. weruva people are snakes and liars. their subpar cat food killed hundreds of cats this year in Australia.


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