Louse infestations in cats and dogs are quite rare. They are most common in vulnerable pets (young, old or unwell) and pets kept in dirty, overcrowded conditions.
Lice cause itchy, scaly skin, dandruff and a dry coat. Some lice cause illness and anaemia by sucking blood.
Treatment from your vet to cure the problem is often relatively simple and the sooner you get the problem diagnosed the easier it is to treat.