A method for providing nutrition to critical care animals such as dogs and cats is provided which comprises administering an amount of an artificially produced canine or feline milk substitute composition. The canine milk substitute composition comprises, on a dry matter basis, from about 35 to 45% by weight protein, from about 25 to 35% by weight fat, and from about 10 to 25% by weight carbohydrates. The feline milk composition comprises, on a dry matter basis, from about 30 to 50% protein, from about 25 to 50% fat, and from about 10 to 25% carbohydrates.