What do cats eat
Cats are obligate carnivores requiring animal-based proteins like taurine and arginine. This article details their specific nutritional needs, the risks of plant-based diets, and the differences between dry and wet food formulations.
Cats require a diet composed almost entirely of animal flesh, specifically rich in protein, taurine, and arginine, which they cannot synthesize from plant sources. This biological necessity stems from their evolution as obligate carnivores, meaning their bodies are designed to extract nutrients from meat rather than plants.
Why plant-based diets fail cats
Cats lack the specific physiology to extract nutrients efficiently from raw plant-based materials. They cannot convert carotenoids to vitamin A, cannot synthesize enough vitamin D, and cannot convert tryptophan to niacin. Furthermore, they have an intolerance to glutamic acid, which is abundant in plant matter but low in animal tissue. Without these animal-derived nutrients, cats develop severe health issues, including heart failure from taurine deficiency or liver damage from vitamin A toxicity.
Historical context of cat feeding
Specialized cat food is a relatively modern invention. In the 19th century, cats in London were fed horse meat by itinerant traders known as Cats' Meat Men. The prevailing view that cats were self-sufficient hunters was challenged by French writers in the 1800s, who argued that well-fed cats were actually more effective vermin-killers. By 1876, Spratt's began producing ready-made cat food to replace the unwholesome practice of feeding boiled horse flesh, marking the shift toward commercial formulations.
Dry versus wet food mechanics
The physical form of the food dictates its nutritional profile and moisture content. Dry kibble contains only 8–10% moisture and relies on high carbohydrate levels to maintain its shape during the extrusion process, where meat is ground, cooked at high heat, and molded. This high carbohydrate content has been associated with an increased risk of obesity and type 2 diabetes in felines. In contrast, wet food contains 75–78% moisture, matching the hydration levels of a cat's natural prey, and is typically sold in aluminum or steel cans.
Risks of non-conventional diets
Diets that deviate from established nutritional standards carry specific dangers. Cats fed exclusively on raw freshwater fish can develop a thiamine deficiency, while those fed only liver may suffer from vitamin A toxicity. Homemade vegetarian or "natural" diets often contain excessive protein and phosphorus while lacking essential calcium, vitamin E, and microminerals like copper and zinc. Even soy-based proteins, used as a vegetable protein source in some commercial foods, can interfere with thyroid function by inhibiting enzymes that regulate thyroxine levels.
Managing gastrointestinal health
The cat's digestive system requires specific nutrients to maintain a healthy microbiome and cellular turnover. For cats with gastrointestinal diseases, the solution involves easily digestible ingredients fed in small, frequent portions to avoid overwhelming the system. The inclusion of fermentable fibers like fructooligosaccharides (FOS) can improve gut health by shifting fatty acid production toward short-chain fatty acids, which support cell turnover and immune function. Conversely, undigested fat reaching the colon can be fermented, worsening symptoms like diarrhea.
Regulatory standards and treats
In the United States, products labeled "complete and balanced" must meet standards established by the Association of American Feed Control Officials (AAFCO), either through nutrient profiles or feeding trials. Terms like "premium" or "holistic" have no legal definition. Treats, whether dry, wet, or semi-moist, should not exceed 10% of a cat's daily calorie intake, as they are often used to supplement rather than replace a nutritionally complete diet.
Environmental and industry implications
The pet food industry faces the dual challenge of meeting high meat consumption demands while addressing sustainability. The production of commercial cat food places significant pressure on livestock farming and fish stocks. As the industry evolves, manufacturers must balance the biological imperative of high-protein, animal-based nutrition with consumer preferences for grain-free or sustainable options, all while ensuring that emerging health concerns related to commercial diets are addressed.