Prevalence of Demodex gatoi in shelter and feral cats in a southeastern region of the United States.

Demodex gatoi is a contagious ectoparasite that causes pruritic dermatitis in otherwise healthy cats. The diagnosis of this mite can be difficult, and its prevalence is unknown. The goal of this study was to identify the prevalence of D. gatoi in a population of cats with no known previous exposure to treatments using real-time PCR and superficial skin scrapings. Fifty cats from shelters and 50 cats from feral populations of eastern Tennessee were included in this study. To identify the presence of D. gatoi, superficial skin scrapings and plucked hairs were collected from multiple sites for microscopic and PCR evaluation, respectively. Ten of 100 cats were positive for D. gatoi. Nine cats had a positive PCR for D. gatoi with negative skin scrapings. One mite was identified on superficial skin scrapings from one cat, which was negative on PCR. Four of 50 feral cats (8%) were positive for D. gatoi. Of the shelter cats, four of 20 stray cats (20%) and two of 30 owner-surrendered cats (6.67%) were positive. Only one of 10 positive cats had skin lesions. These findings demonstrate that asymptomatic cats represent a source of infection for D. gatoi to healthy cats. This mite should be considered a differential diagnosis in pruritic cats with a history of potential exposure. Additionally, skin scrapings appear to be insensitive; thus, multiple diagnostic tests, including PCR, should be performed to identify the presence of D. gatoi.