Immunotherapy trial for horses in British Columbia with Culicoides (Diptera:Ceratopogonidae) hypersensitivity

Immunotherapy was used to treat horses in British Columbia for Culicoides hypersensitivity. This is a severe, chronic, recurrent allergic disease of horses that results in severe irritation, large lesions, hair loss and secondary infection in the ventral midline, mane, and proximal region of the tail. A crude Culicoides extract was injected subcutaneously, in increasing doses, into 10 horses that were affected severely by the disease. Weekly doses reduced the clinical signs in 9 of the 10 horses in the 1st yr. Eight horses were treated with a maintenance dose during a 2nd yr. After the 2nd yr, 3 horses were completely free of clinical signs, 3 showed much less severe clinical signs than in untreated years, and 2 showed moderate reduction in clinical signs. Dosage, frequency of injections, and possible future applications of this technique are discussed.