Comparison of Adhesive Tape Impression Cytology, Hair Plucks, and Fungal Culture for the Diagnosis of Dermatophytosis in Dogs and Cats

SIMPLE SUMMARY: The purpose of this study was to evaluate the sensitivity of adhesive tape impression (ATI) cytology for the diagnosis of dermatophytosis in dogs and cats and to compare this test with the most commonly used diagnostic tests: microscopic examination of plucked hairs and fungal culture. Diagnosis of dermatophytosis can be challenging in some cases, especially in dogs with kerions, and at least two tests should be used for diagnosis since no single test can be identified as the “gold standard”. The present study supports this conclusion, as in comparison between the three diagnostic tests in dogs and cats with dermatophytosis no significant difference was found, apart from dogs with kerion. In this group of dogs, ATI cytology and fungal culture had the same sensitivity that was higher than hair plucks, and hair plucks were significantly less sensitive than fungal culture. Additionally, adhesive tape preparations can be superior to other diagnostic tests in cats. ATI cytology is easy to perform, inexpensive, noninvasive, minimally stressful for the animals, and can be a useful in-house diagnostic test for dermatophytosis. However, more studies with larger populations should be conducted to further evaluate the sensitivity of this diagnostic test in dermatophytosis. ABSTRACT: Rapid diagnosis of dermatophytosis is essential for early treatment induction and prevention of spreading to other animals and humans. No single diagnostic test is identified as the “gold standard”. The purpose of the study was to evaluate the sensitivity of adhesive tape impression (ATI) cytology in dermatophyte identification and to compare three diagnostic tests for dermatophytosis. Thirty dogs, with alopecia (n = 19) or kerion (n = 11), and fifteen cats with alopecia were included in the study. Dermatophytosis was diagnosed with tape preparations in 82.2% (37/45) of cases, while with hair plucks in 66.7% (30/45) and fungal culture in 80% (36/45). In kerions, tape preparations and fungal culture had the same sensitivity (10/11, 90.9%) that was higher than that of hair plucks (4/11, 36.4%). The sensitivity was higher in cats than in dogs with alopecia for all tests, 80% versus (vs.) 73.7%, 86.7% vs. 68.4%, and 93.3% vs. 68.4% for cats and dogs for hair plucks, fungal culture, and tape preparations, respectively. No significant difference was found between the three tests, except for dogs with kerion. Hair plucks were less sensitive than fungal culture in kerions (p = 0.041), while in comparison with tape preparations they were marginally not significantly different (p = 0.078). ATI cytology is a useful diagnostic test in dermatophytosis, in dogs with kerion as well as cats.