A cat looking at a pig made of meat

4 dangerous ingredients that should not be in cat food (but are!)

1. Pig meat

A can of cat food usually contains multiple kinds of meat mixed together. We often see meats such as cow, chicken, lam, bird, salmon, duck and so on. But pig meat is rarely included. Why is that?

If you see pork on the can, give it a pass

Aujeszky disease (aka pseudorabies) is a type of illness caused by a virus known to be carried by pigs. Pigs themselves are completely resistant to the virus, but cats are extremely sensitive and will easily get infected by it. Uncooked pig meat in particular is highly dangerous because it is known to contain viral Aujeszky.

Once the virus enters the body, it will spread to all parts of the nervous system and do tremendous damage within the span of a few days. There is currently no known cure for Aujeszky disease, so you would be wise to avoid cat food with pig meat altogether.

2. Canned and raw tuna

You’ve probably seen someone feed their cat a can of tuna before. Is it bad? Yes, says Dr. Joanna Woodnutt (MRCVS):

“Tinned tuna is not nutritionally complete, so giving too much can unbalance your cat’s diet. It’s also high in fats, and contains a lot of calories – one 95g tin contains more than half of a cat’s daily allowance of calories! Tuna, especially in brine, has too much salt (sodium), which can cause dehydration, changes in blood pressure, and put strain on the kidneys.”

Other canned fish like salmon and sardines also contain a lot of added salt. When given occasionally as a treat, the risk is small. But if you make canned fish a major part of the diet, all that added sodium could become very stressful on your cat’s kidneys.

Mercury levels

There is also the issue of high mercury levels present in fish meat. This metal tends to accumulate in species that are higher up the food chain. And since cats have relatively small bodies, a small amount of mercury is enough to elicit the symptoms of mercury poisoning, which could eventually result in kidney failure.

3. Soy

Soy is a high quality plant protein that contains many essential nutrients: It is high on vitamins and fibers, and contains little to no cholesterol.

Since it is essentialy made up from the same building blocks as meat, cat food producers use it all the time as a cheap alternative to real meat. But is it a viable one? As it turns out, soy is definitely not the healthiest of foods in many regards.

You definitely want to avoid any cat food that lists soy as an ingredient on the packaging

Soy is one of the most gentically modified plant species on our plant, and it’s effects in cats are profound. Certain studies have shown that there can be very severe negative effects upon ingestion:

  • The amount of indigestible fibre can lead to excessive gas production
  • Those fibers also retain a lot of liquid, which can result in diarrhea
  • The large amount of carbohydrates may lead to high blood sugar
  • Pyto-esterogen has an effect on hormone levels; has been shown to led to developmental issues.
  • Anti-trypsine makes the metabolisation of proteins more difficult

Taking all these into consideration, I think it’s safe to say that soy is not a great alternative to meat in cat food. You may want to consider spending your food money on something else.

4. Carrageenan

This additive is often used to thicken up foods and drinks, and also helps preserve food. Carrageenan is a natural ingredient made from seaweed. It comes in two forms; degraded and undegraded. Degraded carrageenan is very bad for cats, as research has shown that it can cause ulcers and cancer in the stomach and digestive tract. No wonder the FDA has banned this stuff.

The real issue however, lies in the fact that undegraded carrageenan is not banned and supposedly “safe for consumption”. The issue here is that the body itself can degrade carrageenan, which effectively makes this form of the substance just as toxic.

Our advice? Give it a pass.

Time for a change?

That’s it folks! Here’s three ingredients that you definitely want to avoid from now on. If you just discovered that your cat food is no bueno, you probably want to switch over to a different brand or product. Since cats are often pretty reluctant to try new things, we wrote this handy little guide on how to change a cat’s diet.


  1. So what food is the best for the cat’s. Usually i give or rather i by fish for my cat’s, i cooked with vinegar & when is done i mix with rice, also i lways buy cuties flavor tuna, is that good?

    1. Hey Gina 🙂

      Cooked fish meat is OK to give every now and then, but you really need to be careful not to feed too much of it. General guidelines state no more than 10% of daily calories. The reason is, some species of fish like tuna contain a lot of mercury, which will build up in your cat’s body and eventually cause mercury poisoning. Fish meat also does not contain all essential nutrients. We therefore recommend making fish only a small part of your cat’s diet.

      Tuna flavored food (from a brand like Cuties) is fine. The best food is one that is matched to your cat’s life phase (kitten, adult, senior) and has a balanced profile, which means it contains all the essential nutrients in the right proportions. You can give that as often as you want!

      Hope this answers all your questions!

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