Sheep and goat pediculosis can result in stress-associated production loss, damage to wool and hair, alopecia, dermal irritation, and anemia. Diagnosis can be challenging and requires that the wool or hair be parted at predilection sites. A range of treatments are effective; however, few products are labeled for the control of lice on sheep and goats.
Sheep may become infested with one species of chewing louse (Bovicola [formerly Damalinia] ovis) , and three species of bloodsucking lice (Linognathus pedalis, Linognathus ovillus, and Linognathus africanus); see the table Predilection Sites of Sheep and Goat Lice.
B ovis is also referred to as the sheep body louse. Despite its name, L africanus is found outside Africa, including in the southern and southwestern US, Central America, and India. L africanus has also been reported from a variety of hosts, including goats and several species of deer.
Goats can be parasitized by three types of chewing lice (Bovicola [formerly Damalinia] caprae, Damalinia limbata, and Bovicola [formerly Holokartikos] crassipes); and three types of bloodsucking lice (Linognathus stenopsis, L africanus, and L pedalis).
L stenopsis is found on both short-haired and Angora breeds of goats, and has occasionally been reported on sheep in various parts of the world. It is found mostly on the long-haired parts of the hind legs and back. Severe infestations are rare. The goat biting louse B caprae is most frequently found on short-haired goats. Both B crassipes and D limbata are serious pests of Angora breeds. For the host and predilection sites of each species, see the table Predilection Sites of Sheep and Goat Lice.
Pathogenesis and Disease Transmission of Lice in Sheep and Goats
Affected animals often rub vigorously on fencing and pens, damaging the coat and causing excoriations. Pediculosis is one cause of "wool slip" in sheep. Infestations can result in production loss, weight loss, wool and hair damage, and secondary infections.
Sheep and goat lice are not known to vector any disease agents within the US.
Treatment of Lice in Sheep and Goats
Limited compounds
Pyrethrins and pyrethroids are labeled for control of lice in sheep and goats. Shearing may be necessary to achieve effective louse control on sheep and goats. Treating again 2 weeks after initial treatment is often necessary. Husbandry problems and individual health problems within the flock or herd should be addressed. Shearing must be done carefully, because clippers may carry lice from animal to animal.
Treatment of meat and dairy animals must be restricted to uses specified on the product label, and all label precautions should be carefully observed. Appropriate meat and milk withdrawal times must be observed.
Key Points
Lice on sheep and goats can result in severe dermal irritation.
Treatment options are limited.
Retreatment is usually required.
For More Information
Parasites of sheep and goats. In: Taylor M, Coop R, and Wall R, eds. Veterinary Parasitology. Wiley; 2015:436-523.
