Diagnostic Tests for Everyday Dermatology Practice

Skin scrapings should be the most common diagnostic test performed in veterinary dermatology. A dull scalpel blade or similar instrument is moistened with mineral oil and used to scrape away some of the epidermis, in which may reside a number of different parasites. There are 2 types of skin scrapes that should be performed. A superficial skin scrape to rule out ecotoparasites of the superficial epidermis and deep skin scrapes to look for demodex (except demodex gatoi). Superficial skin scrapings are helpful in diagnosing Sarcoptes, Notoedres, Demodex gatoi, Cheyletiella, Otodectes, and Eutrombicula (chiggers). For demodicosis, deep scrapings must be performed, as Demodex inhabits hair follicles (although some variants appear in the stratum corneum).