The hypersensitivity of horses to culicoides bites in british columbia.

Culicoides hypersensitivity is a chronic, recurrent, seasonal dermatitis of horses that has a worldwide distribution, but has only recently been reported in Canada. It is characterized by intense pruritus resulting in lesions associated with self-induced trauma.A survey of veterinarians and horse-owners in British Columbia showed no differences in susceptibility due to the sex, color, breed, or height of the horses. The prevalence of the disease in the 209 horses surveyed was 26%. Horses sharing the same pasture could be unaffected. The disease was reported primarily from southwestern British Columbia; it occurred between April and October and usually affected the ventral midline, mane, and tail. Horses were generally less than nine years old when the clinical signs first appeared ([unk]=5.9 yr). Culicoides hypersensitivity was common in the lineage of several affected horses, possibly indicating a genetic susceptibility. Most cases were severe enough to require veterinary attention and some horses were euthanized.