Have you noticed odd-looking ears on bighorn sheep in the South Okanagan, Lower Similkameen, and Ashnola?
When sheep have ears that are oddly shaped, stiff, thickened, crusted, or folded like dog ears, they are showing signs of Psoroptes (pronounced sore-op–tease) infestation. Psoroptes ovis is the name for the mite that causes skin irritation and lesions in sheep — a condition commonly known as sheep scab or mange.
How does it affect sheep?
The first observable signs are yellow-orange staining of hair near the skin, and crusty skin lesions on the neck and shoulders. Mites can cause itching, crusted skin, and hair loss over the whole body, but these extremes have not been reported in BC bighorns since 2011.
Because the lesions are intensely itchy, sheep may spend a lot of time scratching and biting, causing more damage to the skin and distracting from time normally spent feeding. Severe symptoms can cause anemia and weight loss, and may predispose sheep to secondary bacterial infections.
In most cases, adult sheep develop antibodies to Psoroptes ovis, become immune and eventually recover from any disease symptoms. This varies though.
Some sheep are highly resistant to the mites, but can still be carriers that spread mite infestations to other animals. Other sheep may have weaker immune responses and continue to develop skin lesions and hair loss over time.
After an infestation, mites die out on some animals but may persist for months on others that appear healthy and unaffected. In chronically infested herds like some of those in the Lower Similkameen, mites persist primarily in sheep ears.
Mites in the ears can cause excessive head shaking, rubbing and scratching. It is also possible that infested sheep have impaired hearing, as skin crusts build and block the ear canal.
The impacts of this chronic, low level of disease on long-term population health are not clear. Psoroptes infestations have occurred in bighorn herds across the western United States but have only been associated with population declines in a few documented cases. A key factor may be monitoring the health and survival of lambs that are exposed to Psoroptes mites, to ensure that population recruitment is sustainable.
What can be done about it?
Management of Psoroptes infestations in wild sheep is complex. For background, read the review of Psoroptic Mange Occurrence, Risk, and Management Options
We’re planning to develop and address a range of management options during the course of the SOKS Bighorn work. Stay tuned for updates as plans progress.
You can help with disease surveillance
We’re interested in sheep observations anywhere in the South Okanagan and Similkameen, from Kelowna to Keremeos, Princeton to Osoyoos.
Record the date, time, location, group size, number of lambs, and a description of any collars and tags. Keeping in mind the symptoms described above, let us know if you think the sheep look normal or show signs of disease.
Photos are much appreciated! Send us a pic of the whole group if you can – this provides a lot of useful data.
Want to know more about the SOKS Bighorn Psoroptes Monitoring Project? Read all about it here.