Overview of Fleas
Fleas are small, wingless, blood-feeding insects. There are about 2500 different species of fleas, most of them renowned jumpers.
The cat flea (Ctenocephalides felis felis) accounts for more than 90 percent of all flea infections found on domestic dogs and cats in North America and in northern Europe. There are many other species of fleas worldwide that infect pets.
Flea allergy dermatitis, an allergic reaction to the flea's saliva, is one of the most common causes of skin disease in dogs and cats. Flea allergy dermatitis causes severe itching that leads to chewing, compulsive biting, licking, and scratching. Flea allergy dermatitis isn't necessarily caused by an infestation; sensitive pets may react to a single fleabite.
Flea infestations on small or weak pets can cause life-threatening anemia (iron-deficiency anemia, decreased red blood cells circulating through the blood, which means a decreased oxygen level in the blood).
While grooming, cats ingest about 50 percent of the fleas on their body. If the fleas carry pathogens, the cat may become diseased.
Fleas have four life stages: egg, larva, pupa, and adult. Only adults live on pets. The eggs, larvae, and pupae live in carpets and on blankets, so it is important to treat the pet's environment in cases of infestation.