So is tuna good for cats?
Sort of. Tuna contains lots of protein, and cats need protein. It also has certain mineral and vitamins that your cat needs. At the same time, it lacks many other essential nutrients. In other words, tuna contains some good stuff, but not enough good stuff.
So what happens if my cat eats too much tuna?
Tuna isn't a part of a cats natural diet. Although they might love the way it tastes, cats didn't evolve eating tuna and other fish. They developed in dry deserts or jungle environments, where they lived off very different protein sources. As a result, a cat who eats too much tuna is likely to struggle with some of the following issues:
Tuna can't provide a cat with everything it needs to stay healthy. What's more, excess tuna consumption can actually reduce your cat's vitamin B levels. This can lead to yellow fat disease, a medical condition where the body's natural fat stores start to swell and then harden. Symptoms include fever, loss of appetite, extreme sensitivity to touch, and even aggression.
Some cats are allergic to tuna, but this won't stop them trying it! So if you're introducing some tuna into your cat's diet, start off by feeding them a small amount. Then wait 10 mins. If your cat develops any swelling or irritation in or around the mouth, then they've probably had an allergic reaction. Just don't give them any more tuna and it should clear up on its own.
A lot of fish contains mercury, with tuna having a particularly high mercury content. Although harmless in small doses, too much mercury can cause nasty symptoms like tremors, weakness, muscle atrophy, and fever.
It might sound strange, but some cats have been known to suffer from tuna addiction. The smell and taste become so attractive that a cat can refuse to eat any other types of food!
So how much tuna can my cat eat?
This is different for each cat. But, generally speaking, fish should never make up more than 10% of your cats diet. Given that a lot of tuna isn't ideal for your cat, it's best to feed it to them in moderation. Give it to your cat as a treat, or mix some in with their food. Tuna should never be used as a meal replacement.
Can cats eat canned tuna?
Canned tuna is fine for cats, but make sure the tuna is in water and not oil. Cats have very delicate stomachs; greasy oil will easily upset them.
Always read the label, and try to stick to 100% natural tuna products. Some brands are full of artificial flavours which aren't good for your cat. In fact, certain preservatives and additives have been linked to hypothyroidism in cats.
Fresh tuna is probably the best option for your cat. If you're buying it from the fishmonger, just make sure all the bones have been removed and that the tuna hasn't been seasoned. Again, your cat's stomach won't react well to lots of salt, pepper, or other spices.
And it's always best to cook the tuna. Cats will certainly eat raw tuna, but it comes with a much higher risk of food poisoning. Raw fish can also spread parasites.
What about other types of fish?
Most cats will nibble on any kind of fish, and many of them will eat as much fish as you put in front of them. But whether it's tuna, mackerel, cod, or any other kind of fish you can think of, it should always be a treat rather than a staple part of your cat's diet. Stick to the 10% rule. The other 90% of their diet should be high-quality, protein-based cat food.
Tuna is a safe food for cats, but only when eaten in moderation. It should never be used as a substitute for specially designed cat food. It's best to mix it in with your cat's regular meals, or just feed them a few teaspoons of tuna each week. This is a great way of treating your cat without upsetting their natural dietary requirements.