Why Fish Is Bad For Your Cat

On January 2, 2013 by AntheaAppel

cat-and-goldfish We’ve all seen the Saturday morning cartoons of a cat trying to grab the swimming goldfish in a bowl and more than likely if the cat caught the fish, he’d eat it. But, then I’ve seen my cats chase spiders and flies, catch them and then eat them. And, my Burmese is fascinated by the cursor on my computer screen and I bet if he caught that he’d eat it, too. What I’m trying to say is: cats chase small moving objects…it’s part of their predatory instinct.

Yes, cats are meat-eaters and fish and bugs are meat, but it’s a rare sight to see a cat go fishing. I’ve seen photos of bears standing in shallow water catching jumping salmon swimming upstream, but I’ve yet to see a National Geographic photo of a Mountain Lion doing the same. The bottom line is: fish is not a significant food source for cats (even IF you do see a Mountain Lion catching salmon).

It’s a good thing fish is an insignificant food source for cats, because a consistent diet of raw fish can be quite dangerous for a cat. Why? Some fish contain thiaminase, an enzyme that will destroy thiamine (vitamin B1). Thiamine deficiency causes severe neurological symptoms, such as, seizures, stupor, head tilt, ataxia, coma, and left untreated can be fatal. Cats have a higher requirement for thiamine compared to dogs. According to the NRC, an adult cat needs 5.6 mg per kg (2.55 lbs) and an adult dog requires 2.25 per kg. Deficiency is very rare in cats that consume a daily species appropriate diet of raw meaty bones and organs, and that’s because B vitamins are plentiful in animal tissues (chicken liver and beef liver have the highest percentage of B1).

NOTE: Atlantic salmon, trout, cod, flounder, which are common fish that might be fed to cats or dogs, does not contain thiaminase. But, whitefish, goldfish, catfish, bass, smelt, tuna, mackerel, herring, does contain thiaminase (see more HERE).

Yes, thiaminase is destroyed during cooking, but don’t think commercial cooked/processed foods with its added synthetic vitamins are any better. There have been quite a number of pet food recalls in recent years due to thiamine deficiencies. See article HERE. (Preservatives in processed “all-meat” cat-foods inhibit thiamine absorption. Be careful if you feed commercial meat-only products that have been preserved with a sulphur dioxide preservative. These preservatives “hold” the color of the meat for an unnaturally long time so they stay looking good in the fridge. The preservatives can also trigger asthma in cats. Products marketed for pets (eg commercial fresh ‘pet meat’, ‘pet mince’ or processed/manufactured ‘pet food rolls’) may contain sulphite preservatives. Thiamine deficiency can occur when dogs and cats are fed a diet containing sulphite preservatives).

It doesn’t take long to see a thiamine deficiency in a cat. Clinical studies have shown that when a cat was fed a thiaminase-containing seafood diet on a daily basis, such as, raw carp or raw salt-water herring, it only took 23 to 40 days to see signs of a thiamine deficiency. The good news is, the deficiency and its symptoms can be easily reversed on a Thiamine Supplement Therapy, sometimes in just a matter of hours.

This is what a thiamine deficiency in a cat looks like:

(NOTE: The cat in the above video did eventually make a good recovery once he was started on a Thiamine Therapy)

Another reason not to feed your cat a fish-based commercial diet is: it was discovered during clinical trials that when cats were fed canned salmon or tuna the animals developed a Vitamin K deficiency. Symptoms included prolonged blood-clotting time and hemorrhage. While cats can synthesize their own Vitamin K from most food sources, fish-based commercial products may not support sufficient Vitamin K synthesis (researchers don’t know why processed fish products stops Vitamin K synthesis in cats). Therefore, pet food manufacturers will add the synthetic Vitamin K supplement: Menadione. Menadione/Vitamin K3 is toxic, and it has been proven to cause damage to kidneys, lungs, liver, mucous membranes, in lab animals, and yet the AAFCO requires it to be used in any pet food containing at least 25% fish matter. Advocates of Vitamin K3/Menadione say it’s safe in low dosages and that holistic practitioners are making “much ado about nothing.” But since there are little to no regulations as to “how much of whatever” is going into commercial pet food, why take the chance?

NOTE: A cat (and, a dog) on a species appropriate diet, which is full of live enzymes and nutrients will synthesize Vitamin K by the presence of naturally occurring bacteria in the large intestines.This is just one reason why a probiotic is important for your dog or cat.

But my cat loves fish

Of course, he does. Kitties love protein, and even though fish is not a natural food source for felines they can become addicted to fish. But they can also become addicted to chicken, or to any protein source that is fed to them exclusively. The pet food industry knows this and that’s why most commercial cat food is either fish or chicken. The best way to handle this is to rotate your cat’s (or dog’s) diet to avoid addiction to any particular food. Some folks believe that “over-consumption of any one food may lead to an allergy of that particular food.”

NOTE: Animals in the wild don’t develop allergies to their prey food sources (raw food). So, a dog or a cat may develop an allergy to a particular food when they are fed a processed commercial diet and that’s because the chicken, lamb meat, ect., is cooked, and thus, denatured, then it’s mixed with starches and carbohydrates, like grains and veggies, which carnivores cannot digest, plus toxic preservatives, MSG, artificial flavorings, and synthetic vitamins which nobody, including humans, should be consuming. Allergies are the immune systems reaction to toxins. Remove the toxins, and you’ll remove the allergy.

Another cause of food allergies are vaccines (another toxin). Over a hundred years ago, a Nobel Prize winning doctor named Charles Richet discovered that proteins injected into the bloodstream will result in the development of allergy to that protein. Today, the CDC has come to the same conclusion: food proteins in vaccines can cause the development of food allergies. Read the research HERE.

Fish contains iodine, and cats aren’t designed to process a large consumption of iodine, and doing so may lead to hyperthyroidism. Also, long-term ingestion of oily fish, particularly tuna, can also deplete vitamin E resources. Vitamin E deficiency can also cause a very painful condition called steatitis, or “yellow fat disease.” If left untreated, steatitis can be life-threatening.

Unfortunately, because the rivers and oceans have become so polluted—whether from the BP oil spill in the Gulf, or the radioactive contamination from the Fukushima reactors in Japan, or just from years of garbage and chemical waste being dump into our waters—our seafood is now a toxic mess. Therefore, fish at the top of the food chain, such as tuna and salmon, tilefish (listed on pet food labels as “ocean whitefish”), along with king mackerel, shark, and swordfish may contain very elevated levels of heavy metals (including mercury) as well as PCBs, pesticides, and other toxins, such as, PBDEs.

PBDEs are fire retardant chemicals that can be found in high concentrations in some fish and also in house dust. Since PBDEs are known to affect thyroid function, then feeding your cat either a raw fish or a canned fish diet may increase the chances for hyperthyroidism.

More bad news: Farmed fish is not safe either!

Farmed or “pen-reared” salmon (usually marketed as Atlantic salmon but sometimes as Canadian king salmon) has generated front page news in the Washington Post because it can contain cancer-causing contaminants (PCBs and dioxins) in dangerous amounts. These are present in levels sufficient to pose an “unacceptable cancer risk” from eating only one 8 oz. portion per month, according to a peer reviewed study by Dr. David O. Carpenter and his team of scientists as published in “Science” (1/9/04) the Journal of the American Association for the Advancement of Science (AAAS). The source of the contaminants is in the feed given to most “farmed” salmon in their net pens. European farmed salmon had the highest levels, those from South America had the lowest and those from major U.S. markets, including Washington, D.C., had moderately high levels.

For more specific information on the dangers of eating “farmed” salmon (also marketed as “organic” salmon) and its multiple problems (including escapees, disease and parasite transmission to wild populations, and habitat degradation), check out this LINK.

It gets worst: Franken-Fish

On December 17th 2012, the Obama Administration OK’d the first genetically-modified food for human consumption: Aquabounty’s salmon, aka the Frankenfish.

And, because Frankenfish will be cheaper than natural wild salmon—or, even “Farmed” salmon—you can bet it will definitely be in commercial pet food.

What are the risks?

(1) GMO fish are designed for factory farms, where the fish are so crowded and inactive they need to be pumped full of drugs to ward off disease. But GMO fish are less robust, so they’d require more doping.

(2) Inevitably, some fish will escape into the wild, where they will compete and breed with already severely challenged wild fisheries. 5% of frankenfish are fertile. Once their modified DNA makes it into the wild stock, there’s no recalling it.

There are many potential food safety risks posed by GMO salmon, including the potential human (and your pet) health impacts of GMO salmon’s higher hormone levels and increased allergenicity.

(3) Anyone concerned about unknown health impacts from consuming genetically-modified fish would have no label distinguishing GMO fish from natural fish. For more information, visit this LINK.

The Fishing Cat

I did a little research and I discovered this species of cat, The Fishing Cat. This little guy is found in Asia, he loves the water, and he actually does go fishing, hence the name. But the man in the video failed to mention that even though this cat dines on seafood, it also eats rodents and birds. Animals instinctively know what’s good for them, and this cat is smart enough to rotate his protein source.

One Last Word

Does this mean I should never feed fish to my cat? No. Cats need a dietary source of Omega-3 fats, and unless you are feeding your cat grass-fed free-range meats every day (a natural prey in the wild would have plenty of omega-3s) then your cat isn’t getting omega-3s, only omega-6s, and that is not a balanced diet. The best source of omega-3s is going to be fish (or, better yet, fish oil).

So, what to do? I would suggest you look for the safest fish, like, perhaps salt-free can of cooked sardines packed in water. Sardines have a short life-span and there’s a better chance that less toxins have accumulated in the fish. It is also high in calcium and Omega-3s. You could add a few sardines to their raw meaty bone diet of rabbit, duck, turkey, etc. once or twice a month (Note: Raw sardines contain thiaminase). However, I prefer to just add fish oil to my cats’ meals. This way I can see how much EPA and DHAs are in the oil. And because omega-3 is so unstable and quickly goes rancid once exposed to air, I use the gel-caps rather than a pump-bottle. I simply snip them open and pour on top of the food. But, more importantly, remember to always rotate the cat’s protein source, and don’t feed exclusively just a fish dinner.

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