Hog lice and mange mites are two external parasites that thrive during cold weather, and they can spread quickly by direct contact between animals. Hog lice use piercing-sucking mouthparts to feed on blood. Infestations can be especially serious for young pigs.
The hog louse spends its life on an animal. Females glue single eggs (or nits) to bristles; eggs hatch in 2 to 3 weeks. The slate blue to brown lice can blend in with animal skin and be overlooked, even though adults are about ¼ inch long. Preferred feeding sites are around and in ears, under the neck, and inside upper legs.
In combination with other winter stresses, lice can harm large animals, too. A hog louse lives about 5 weeks, but it probably seems a lot longer to swine because lice feed about 6 times a day. Irritation can cause excess scratching and skin lesions, reduced feed consumption, and stunted growth.
Mange mites burrow within the skin of the animal. Strong digestive enzymes dissolve the animal’s tissue and produce a liquid upon which the mites can feed. Infestations cause severe itching, and infested animals rub frequently to get some relief. Scabs usually show up first on the head, especially around eyes, nose, and ears. Mites present in the ears may be missed during examination or treatment and can result in a resurgence of the problem.
Diagnosis and Management
Do not make a hasty “eye-ball” diagnosis; skin scraping from infested areas need to be examined under a microscope to detect these tiny arthropods. Mangy animals tend to gain poorly and are more susceptible to other stresses. Infested animals may bring discounted prices at market.
Options for lice and mange control include sprays, dusts, pour-ons, injection, or feed-through (See Insect Control on Swine, ENT-23). When using sprays, remember where these pests are on the animal and treat thoroughly. Spray pressure must be sufficient to be effective against mites and the animal must be wetted thoroughly. Treat when conditions will allow animals to dry rapidly.
by Lee Townsend, Extension Entomologist