Lice infestation is known as pediculosis. Lice are host-specific, in that, dog lice only infest dogs, cat lice only infest cats, and so on. However, lice can bite a human, but are not considered contagious except for dog to dog or cat to cat transmission.
Chewing lice, also known as biting lice, have wider heads and feed on hair or skin scales. They can cause hair loss, skin irritation or secondary infections.
Sucking lice have narrow heads and feed on blood. They can cause hair loss, skin irritation, blood loss, and secondary infections.
Trichodectes canis is a chewing louse found on dogs and wild canids throughout the world and is a vector of the dog tapeworm, Dipylidium caninum. This louse causes little irritation except in heavy infestations.
Felicola subrostratus, a chewing louse, is usually found in large numbers only on aged or diseased cats and on some wild felids.
Linognathus setosus is a sucking louse occasionally found on the dog (particularly on long-haired breeds) and wild canids throughout the world. It causes little irritation except in heavy infestations.
Pediculosis is a treatable disease. If you suspect your animal is infected with lice, seek veterinary care immediately.