SARCOPTIC MANGE AND IATROGENIC HYPERADRENOCORTICOIDISM IN A DOG UNDERGOING HYPOSENSITIZATION FOR ATOPY BASED ON RAST TESTING

A 3.5-year-old Labrador Retriever was presented with a two-year histor y of non-seasonal, severe pruritus, which was not responsive to daily corticosteroids. Immunotherapy based on a positive in vitro RAST(1) (r adioallergo sorbent testing) for aeroallergens was used unsuccessfully for 18 months. At presentation, the dog showed typical signs of hyper adrenocorticism. Adrenocorticotrophic hormone (ACTH) stimulation testi ng demonstrated that this was iatrogenic in nature. Sarcoptic mange wa s diagnosed on skin scrapings. Response to ivermectin therapy and cort icosteroid withdrawal was dramatic. There has been no relapse of the d isease during a 10-month follow-up period. This suggests that sarcopti c mange was the primary disease rather than secondary to corticosteroi d therapy, although longer follow-up is needed to rule out a seasonal allergen. The use of serological testing for the diagnosis of atopy is discussed.