Which nutrient is essential for a cat's diet but not for dogs?

Taurine is an essential nutrient specifically required in a cat's diet because felines are unable to synthesize it adequately on their own. This amino acid plays a critical role in various physiological functions in cats, including vision, heart function, and reproduction. Without sufficient taurine intake, cats can develop serious health issues, such as dilated cardiomyopathy, retinal degeneration, and reproductive problems.

In contrast, dogs can synthesize taurine from other amino acids like cysteine and methionine, which makes it non-essential for them. Therefore, while both species have unique dietary requirements, taurine's designation as an essential nutrient is specific to cats.

Other nutrients listed, such as vitamin A, omega-3 fatty acids, and fiber, are important for both cats and dogs, although their specific dietary requirements might differ. Cats typically require preformed vitamin A from animal sources, whereas dogs can convert beta-carotene into vitamin A from plant sources. Omega-3 fatty acids are beneficial for both species but are not as uniquely essential to cats as taurine is. Fiber is important for digestive health in both cats and dogs, serving important but similar roles.