Cat owners know that few cats can resist the taste of tuna. The taste and smell hold a powerful appeal that will bring almost any cat running to the kitchen at the sound of an opening can. However, concerns have been raised about the safety of tuna for cats, and it is important for cat owners to understand the issues involved when deciding on the best foods to meet their cats' nutritional needs. Cats love tuna and can be indulged if it's done right.
The most common concern raised in conjunction with tuna is mercury and not just for cats. Because tuna are predatory fish positioned high in the food chain, environmental toxins like mercury accumulate in their bodies in greater concentrations than are found in prey species, as their bodies retain the mercury present in the organisms they consume. Mercury levels in tuna can vary significantly, though on average, humans are advised not to consume more than two cans of tuna per week. As cats are much smaller than humans, their threshold for safe mercury consumption is commensurately lower.
Nutrient Deficiency and Malnutrition
Tuna that is prepared for human consumption contains an enzyme that destroys thiamine, a nutrient essential to neurological and cognitive function, cardiovascular health, and vision. Cats that eat plain canned tuna on a regular basis can develop thiamine deficiency, which can manifest in various neurological symptoms, including seizure.
One of the biggest problems is not what the tuna contains, but what it lacks. A cat should not be fed a diet primarily consisting of canned tuna because it is nutritionally incomplete. Tuna lacks significant amounts of vitamin E, a deficiency of which can result in a serious condition called steatitis. Many other important nutrients, such as calcium, iron, copper, and numerous vitamins, are lacking in canned tuna, making it a poor substitute for cat food. Most commercial brands of cat food also contain added taurine, a compound essential for feline health. Without taurine, cats can develop several health problems, including hair loss, retinal degeneration and blindness, and heart problems. Any food lacking in these nutrients should ever be used as a cat's primary food source.
Irresponsible Fishing Practices
In addition to the nutritional problems with feeding human-prepared tuna to cats, overfishing is another major concern. Several of the species of tuna used for commercial fishing are endangered or depleted, but continue to be heavily fished. Paul Watson, founder of the organizations Greenpeace and Sea Shepherd, asserts that domestic cats worldwide eat more tuna in total than wild dolphins. Regulation and oversight of the commercial fishing industry is weak, so as long as the demand for tuna remains high, the fishing practices that threaten the survival of many species of tuna will continue.
Cats love the taste of tuna, so many cat owners are reluctant to cut it out of their pets' diet entirely. Feeding a cat the occasional treat of canned tuna is unlikely to harm her, as most of the problems associated with canned tuna for cats occur when tuna comprises a substantial or primary element of the cat's nourishment. Still, there are ways to indulge a cat's taste for tuna more safely. Choosing tuna for cats and treats that contain tuna alongside other seafood or meat ingredients allows a cat to enjoy the taste of tuna without making it a large part of her diet. Commercial cat foods specifically designed to meet a cat's nutritional needs do not carry the same risks as canned tuna for cats, as other ingredients make up for the nutrient deficiencies of the tuna.