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

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.

Prevalence of dermatophytosis and Malassezia infection in dogs and cats in Thonglor Bangkok Pet Hospital in Ho Chi Minh City, Vietnam

“…The indirect examination for identification of dermatophytosis was fungal culture, which commonly used Sabouraud dextrose agar (SDA) or Dermatophyte test media (DTM) (Bouza-Rapti et al, 2023). The DTM was an innovative SDA adding cycloheximide, gentamycin, and chlortetracycline to prevent fungal and bacterial contamination (Kaufmann et al, 2016).…”

“…Dermatophytosis should be identified by rapid diagnostic tests for early treatment and prevention. At least two diagnostic tests were essential for dermatophyte detection, as no single test could be considered the "gold standard" (Bouza-Rapti et al, 2023). So the most common techniques used for dermatophyte identification were the hair plucking and fungal culture.…”

“…So the most common techniques used for dermatophyte identification were the hair plucking and fungal culture. And another method was ATI that was the valuable and sensitive diagnosis to detect dermatophytes in dogs and in cats with kerion for quick test (Bouza-Rapti et al, 2023). After collecting samples by impressing three times on the suspected lesions, then the slide was stained with a few drops of Giemsa or Blue Diff-Quik and observed under the microscope with 40x or 100x magnification to identify the presence of fungal hyphae, macroconidia, or arthrospores (Figure 1) (Begum & Kumar, 2021).…”

“…The diseases gradually became a special attention in public health, particularly in dogs and cats. Various diagnostic methods could be used in Malassezia infection and dermatophytosis, including cytological examination and fungal culture, such as cotton swab methods, adhesive tape impressions (ATI), and dermatophyte test medium (DTM) culture (Bouza-Rapti et al, 2023). Malassezia otitis could be detected through cotton swab methods and microscopic examination.…”