Only a limited number of compounds are registered for treatment of mange in sheep and goats. Hot lime sulfur spray or dip is labeled for use against sarcoptic, psoroptic, and chorioptic mites in sheep. Treatment should be repeated every 12 days if needed. Certain formulations of permethrin sprays are labeled for mange in sheep and goats.
As with cattle, permethrin is generally not considered the compound of choice; however, if used, the animals should be thoroughly wet with the product and re-treated in 10−14 days. Topical treatments are more likely to be effective if sheep are freshly shorn.
Oral ivermectin sheep drench is not labeled for treatment or control of mange. Although single doses of oral ivermectin have been shown to decrease the number of Psoroptes ovis mites within 24 hours, a single oral dose is not considered curative. For these reasons, extra-label drug use of macrocyclic lactones in sheep and goats is common. However, practitioners should consider compounds labeled for a large range of species, the production system of the animals treated, and any warnings against use in species not listed on the label.
Outside the US, injectable ivermectin is approved to treat Psoroptes ovis in sheep at the labeled dosage of 200 mcg/kg, two doses administered 7 days apart. Also outside the US, an oral moxidectin formulation is registered for use against Psorobia ovis, and an injectable formulation at the registered dose (200 mcg/kg) administered 10 days apart has been demonstrated to be effective in treating Psoroptes ovis.
When faced with the treatment of mite infestations in sheep and goats in the US, the National List of Reportable Animal Diseases should be consulted to determine the current reporting status.(1)
Sarcoptic Mange in Sheep and Goats
Throughout the world, Sarcoptes scabieiovis infests sheep and S scabieicaprae infests goats, causing sarcoptic mange. However, S scabieiovis is rare in the US. This mite infests nonwoolly skin, usually on the head and face. Typical of scabies, lesions manifest with formation of crusts and intense pruritus. Affected animals have decreased reproduction, meat gain, and milk yield.
In goats, S scabieicaprae is responsible for a generalized skin condition characterized by marked hyperkeratosis. Lesions start usually on the head and neck and can extend to the inner thighs, hocks, brisket, ventral abdomen, and axillary region.
Both S scabieiovis and S scabieicaprae are zoonotic. Consistent with other animal variants of Sarcoptes, zoonoses are initiated from direct contact with infested animals but are self-limiting infestations.
Chorioptic Mange in Sheep and Goats
Chorioptes bovis infests sheep and goats worldwide, causing chorioptic mange. Prevalence of C bovis is more common in rams than in ewes or lambs. Infestation of C bovis on goats is fairly common, with most of a herd infested. Distribution of lesions is the same as that in cattle, with papules and crusts on the feet and legs.
Most sheep are subclinically infested with C bovis. However, C bovis can cause exudative dermatitis on the lower legs and scrota of rams (scrotal mange). Semen quality may be affected, presumably due to increased temperature of infested scrota.
Psoroptic Mange in Sheep and Goats
Psoroptes ovis is a highly infectious and severe infestation of sheep, causing psoroptic mange. This mite has been eradicated from sheep in Canada, New Zealand, and the US but persists in many countries, including some in Europe.
Intense pruritus leads to large, scaly, crusted lesions that develop in more densely haired or woolly parts of the body. Lesions begin on the back and side but may become generalized and cover a large portion of the body. Animals bite, lick, and scratch in response to the pruritus, which results in wool loss and secondary bacterial infection. If affected sheep are not treated, they may become emaciated and anemic and possibly die.
Courtesy of Dr. Jennifer Ketzis.
Psoroptic mange (ear mange) in goats and sheep is caused by P cuniculi, which is likely a variant of P ovis. P cuniculi typically infests the ears of goats but can spread to the head, neck, and body.
Infestation of P cuniculi in goats can be common, with 80%–90% of a herd infested. Disease can range from subclinical to scaling, crusting, inflammation, alopecia, ear scratching, head shaking, and rubbing of ears and head to alleviate irritation. Although the course is chronic, the prognosis is good with appropriate treatment.
Demodectic Mange in Sheep and Goats
Demodex ovis infests sheep and D caprae infests goats, causing demodectic mange. Demodectic mange in sheep is not common, whereas D caprae mites are relatively common in goats. Lesions are similar to those in cattle.
In goats, nonpruritic papules and nodules develop, especially over the face, neck, shoulders, and sides or udder. Demodectic mange in goats occurs most commonly in kids, pregnant does, and dairy goats. The nodules contain a thick, waxy, grayish material that can be easily expressed; mites can be found in this exudate. The disease can become chronic.
Psorergatic Mange in Sheep and Goats
Psorobia ovis (formerly Psorergates ovis) is a common skin mite of sheep in Africa, Australia, New Zealand, and South America, which causes psorergatic mange. Most infested sheep are not affected, but intense generalized pruritus and scaliness, with matting and loss of wool, can result from infestation with P ovis. All breeds of domestic sheep are susceptible.
Because of their small size, the mites are difficult to find in skin scrapings. This disease can cause substantial economic losses via weight loss and wool damage. Treatments effective against sarcoptic, chorioptic, and psoroptic mange in sheep are expected to be efficacious for psorergatic mange.
References
National list of reportable animal diseases. USDA. https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/monitoring-and-surveillance/nlrad/ct_national_list_reportable_animal_diseases
