Lysine is an essential or indispensable amino acid. In other words, the dog and cat are unable to produce an adequate quantity to support their normal physiological functions and must therefore obtain it from the diet. If the diet is inadequate it can result in depressed intake, retarded growth and development, and graying of feathers and fur among various species.

L-carnitine is a supplemental amino acid (ingredient) commonly found in low-fat, “light” or so-called diet foods for both dogs and cats. For the most part, the body produces an adequate amount of carnitine (L-isomer metabolite) to fulfill its role in the conversion of fatty acids into usable energy.

Methionine is one of the 10-plus essential amino acids that are required by both the cat and dog

One of the first reports in the literature regarding taurine was its isolation from ox bile in 1901; hence its name was derived from "Taurus" the bull. That's why, among other reasons, today it is found associated with energy drinks like Red Bull, fueling the perception of strength and vitality.