Flea Control and Flea Bite Allergies in Dogs & Cats http://www.petmd.com/dog/conditions/skin/c_mult... Flea bite hypersensitivity or flea allergic dermatitis is very common in dogs and cats. In fact, it is the most common skin disease for pets. Flea allergies usually develop when pets are young (less than one and up to five years of age), but it can begin at any age. A flea's saliva is actually believed to be cause for the pet's allergy or sensitivity.
The flea life cycle includes the adult flea, eggs, larva and pupa. Adult fleas do bite, but cannot survive long if they are not on the pet. Once they lay their eggs they will fall off the pet. The rest of the flea's life cycle then occurs on the host pet.
