Physiologically speaking, carnitine helps turn fats into fuel for the cells. It is consequently very useful and effective during physical effort, especially when it is sustained. In some dog breeds (Boxers, Dobermans, Cocker Spaniels, etc), serious heart disease is often related to deficient production of carnitine by the body.Weight loss can be accelerated in obese animals by adding carnitine to the food.
Carnitine is a non-essential amino acid normally made by the body from two other amino acids, lysine and methionine. It becomes essential in food only when the body is unable to synthesise enough of it to cover its needs. Its chemical structure allows two forms of the molecule, D and L. Only L-carnitine is active and effective.
Energy is mainly produced in dogs and cats through the oxidation of fat in the mitochondria, which are tiny power generating plants in the cells. The role of carnitine is to shuttle fatty acids through the membrane around each mitochondria. Carnitine also has an important role to play in reproduction. In some species, carnitine supplementation during gestation and lactation increases the weight of newborns and the number of animals in a litter.
Besides synthesis in the liver, food is another source of supply. While plants contain negligible quantities of carnitine, fresh meat is a rich source (mutton and lamb in particular).