Raw egg white contains an enzyme which destroys biotin in the ration. Experiments show with25 to 30 percent of the ration as raw egg whites, this condition will develop. Newborn foxes will show the deficiency if the females are deficient.
Symptoms take a number of weeks to develop (up to 12 or 15). They include fur loss over body and tail. The fur color becomes gray, especially around the muzzle. Eye infections may develop along with leg weakness. Eggs are an excellent source of high quality protein provided they are cooked, thus destroying the harmful enzyme.