Can immunosuppressive therapy facilitate the diagnosis and affect the clinical signs of canine scabies? A retrospective study of 79 cases.

Abstract

Scabies infestation is one of the most pruritic dermatoses of dogs. It is often misdiagnosed and dogs are treated with immunomodulatory drugs (IMD) to relieve pruritus. The primary goals of this study were to determine the impact of IMD on skin scraping results, pruritus level and extent of skin lesions, and to evaluate whether disease duration is associated with positive skin scrapings and contagion. Seventy nine dogs with a final diagnosis of scabies. Inclusion in this retrospective study required a positive skin scraping for scabies or a clinical response to an acaricidal treatment trial. The average pruritus score of dogs that received IMD (8.71) was significantly higher than those that did not (7.43; P = 0.03). However, there were no significant differences in either the rates of positive skin scrapings (79.6% versus 59.1%; P = 0.13) or the mean number of body sites affected (3.8 versus 3.4; P = 0.30) between dogs that received IMD and those that did not. Neither skin scraping status nor duration of clinical signs were correlated with a report of contagion within the household. IMD was associated with a significant increase in the pruritus level, but not with the mean number of lesional body sites. Dogs exposed to IMD had a 20.5% higher rate of positive skin scrapings. This difference could be clinically relevant and lack of statistical significance may indicate an underpowered study.