Egg

Raw egg white contains avidin, a protein that binds biotin. Heat breaks down most of it, and the egg in cat food is cooked or dried, so the problem is greatly reduced.

Egg is an animal protein used in many dry cat foods, usually dried. The Merck Veterinary Manual explains that raw egg white contains avidin, which binds biotin and blocks its absorption, and that naturally occurring biotin deficiency is very rare in dogs and cats. The egg in dry food has been cooked or dried. For a cat with a medical condition or an egg allergy, ask your veterinarian.

Source: merckvetmanual.com

Egg adds protein with a very complete set of amino acids. Nutrition scientists use egg as the reference protein when they compare other proteins, and cats digest it easily. Egg also brings biotin, choline and lecithin. In dry food it is often listed as dried egg product, a convenient powder form.

Dried egg product is egg that has been dried into a powder. Labels may also say dehydrated egg, dried egg, dried eggs, egg product or eggs, and Pettings counts all of these as egg. Drying removes the water, so a small amount adds a fair bit of protein. The dried form keeps well in kibble.

Some cats are. Tufts veterinary nutritionists list egg with chicken, beef and dairy as the most commonly reported food allergies in dogs and cats, with fish also common in cats. Most allergic pets react to animal proteins. If you suspect an egg allergy, a veterinarian can run an elimination diet trial to find the cause.

Source: sites.tufts.edu

Pettings gives egg 5 out of 5 and lists it as a named animal protein. It appears on 57 of the 149 dry cat foods we list, counting forms such as dried egg product. The score is for the ingredient alone. Each food's page shows how it scores overall.