Why is milk bad for cats? Common dietary misconceptions about cats

Bad idea, little Jimmy

Cats have always had strange myths surrounding them. Although, sometimes I really do feel like my cat has nine lives since he’s been through so much! Some of these misconceptions can actually be dangerous towards a cat’s health. I would never recommend feeding them these things, no matter how much pop culture references these. I find that any type of dairy and most fish is just a big no for cats, and you might be shocked to hear that.

Milk is bad for cats

Let’s get this straight, most cats are lactose intolerant. They stop drinking milk when they are kittens like many animals do in their lives. Specifically, until they’ve been weaned.

At around 8 weeks, they lose their digestive enzymes needed to process milk. That is, they only drink milk for that small period of their life.

If ingested, cats will vomit, have painful stomach cramps, and suffer from diarrhea. What happens is the lactose, which is a type of sugar found in milk, will stay in a cat’s intestines instead of passing into the bloodstream. It will then ferment because of the bacteria in their intestines. This will lead to a whole plethora of problems you and your cat won’t want to deal with.

How did this start anyways? Well cats are attracted to cream and dairy products in general. This is because of the high fat content in cream. When farmers used to milk cows at home much more often, cats would be attracted to the cream that would rise to the top. Our milk nowadays has nowhere near as much fat as the milk from decades ago anyways, so it makes it even harder for them to digest.

The remedy? Just give them water. Cats just don’t need additional milk from the time after they are small kittens. Give them plenty of water and they won’t ask for anything else. We know that cats need a lot of water in their diets anyways so this cannot be ignored.

Canned fish is not good for your cat

It’s true. Contrary to popular belief and pop culture, cats do not need to eat fish. However, you CAN feed them fish now and then, just as long as it’s not their main diet.

In the wild, there are a few species that make rare exceptions and add fish into their diet, but most cats do not consume it in their natural diet, nor their evolutionary ancestors before them.

An actual Fishing Cat

Fish, especially tuna, is notorious for being high in mercury which is deadly for cats. Even in canned food for cats, we just don’t know the percentage of mercury it has. Companies claim to get the smaller tuna that doesn’t have as much mercury, but why even risk it? Your cat would be perfectly happy and fine with a poultry or rabbit based diet anyways.

In fact, any fish or seafood is actually a high allergy risk for cats. Shadow gets gastrointestinal problems when he eats fish (which I learned a few years ago in my journey to wet food) so I avoid it like the plague. The thing is, fish can be found as a secondary ingredient in poultry based canned food too, so keep an eye out for that. We want to avoid fish.

Canned Fish and Hyperthyroidism

Not to mention, a fish based diet is potentially linked to hyperthyroidism. Hyperthyroidism in cats is a very common glandular disorder. It is an excessive production of thyroxine in the bloodstream which leads to extreme weight loss and increased appetite. It comes with excessive thirst, increased urination, panting, diarrhea and even increased shedding.

One of the reasons being is because fish have PBDEs in them. PBDEs were used as fire retardants in carpet and furniture and are now banned. New research suggests that cats are much more sensitive to PBDEs than originally thought. PBDE’s disrupt thyroid function.

These are some good sources if you want to read more about it. Here and here. I could go on and on about this but I want to mention that the link between fish and hyperthyroidism has not been defined yet. In fact, we are still not even sure what causes hyperthyroidism in cats.

Let me be clear. This is for canned wet food diets that contain fish. Unless you’re going to go out of your way and get raw, farm raised salmon it’s just best to stay away from fish in canned wet food. Every cat has a different situation. If you plan to give your cat raw, farm raised salmon or whatever, great! Just make sure to give your cat other meats to get their other essential nutrients.

Also, Omega-3s are good for your cat! Fish oil is a good choice for omega-3s still, but in moderation. I would say to talk to your veterinarian first before thinking about adding a supplement like fish oil into your cat’s food.

For other fish your cat could eat, I have heard that sardines packed in water are good because sardines don’t live long enough to store toxins in their body.

Do your research- don’t fall for weird myths

In the end, doing your research is the best thing you could do for your cat. That’s how I ended up feeding my cat a wet food diet anyways! This post has been a bit more link heavy, but I think the extra reading will benefit you and your cat anyways, if you want to read into it more. I want to promote the best judgments you can make on your own terms!

Let me know what you think in the comments! I think a good discussion about this is in order. What have you heard about fish in a cat’s diet?