Cats love seafood, and most cats are especially fond of canned tuna and tuna juice. While tuna is fine for cats in moderation or as a treat, too much canned tuna can be bad for your cat. Fish is a great source of protein, but there are a few reasons why a steady diet of human-grade canned tuna can cause health problems for your cat.
Tuna alone is not nutritionally complete, and many cats are allergic to fish. Most fish contain trace amounts of mercury, and the higher up on the food chain a fish is, the more mercury is accumulated in the fish. Tuna is relatively high on the food chain and therefore contains higher amounts of mercury than other fish, leading to an increased risk of mercury poisoning.
Tuna is also high in unsaturated fats. While it is healthy for humans to choose unsaturated fats in their diet, too much can be bad for cats. Consuming too much tuna can cause your cat to develop a Vitamin E deficiency, leading to an inflammation of the fatty tissue, a condition known as steatitis (“yellow fat disease”). Cats that consume large amounts of red tuna in particular are more prone to this painful condition.
Commercial canned “tuna” cat foods are not just straight tuna, but have other added ingredients, vitamins and minerals as well as the amino acid taurine, which is essential to cats. Just make sure to feed your cat a high-quality pet food formulated for cats, and if you choose to feed your cat human-grade canned tuna, limit it to an occasional treat.