Both abrade the skin surface and feed off of body fluids that exude through the very superficial wounds they create. Light infestations usually go unnoticed. Heavy infestations are usually accompanied with excessive itching, scratching and some hair loss. Scabs may also be evident on and around the ears. A veterinarian can confirm the diagnosis by direct examination of the haircoat.
Direct examination is usually all that is necessary, though use of a microscope is very helpful.
The veterinarian will usually prescribe an insecticide shampoo or an injectible insecticide to treat affected guinea pigs. Lice can be transmitted by direct and intimate contact between infested and uninfested guinea pigs. Therefore, pet guinea pigs are very unlikely to harbor these parasites unless they are recent acquisitions that were previously in contact with louse-infested guinea pigs. Established pet guinea pigs could also be infested by being placed in close contact with new, infested guinea pigs. Guinea pig lice do not parasitize people.