Imiquimod treatment for Equus caballus papillomavirus infection in equine aural plaques.

Background Aural plaques are a dermatopathy associated with Equus caballus papillomavirus (EcPV). This disease affects horses of all ages, genders and breeds, and causes sensitivity of the ears. Hypothesis/Objectives The aim of this study was to evaluate the clinical efficacy of 5% imiquimod cream for the treatment of aural plaques and to compare the PCR detection of EcPV 3, 4, 5 and 6 before and after treatment. Animals Eight horses diagnosed with aural plaques (14 ears) were used. Three mares with unilateral aural plaques were used as untreated controls. Methods Imiquimod cream was applied every 48 h until complete resolution of the aural plaques was observed. Animals were evaluated clinically for 180 days after the end of treatment. PCR for detecting EcPV 3, 4, 5 and 6 was performed using aural plaque biopsies collected before and at 90 days after the end of treatment. Results Clinical resolution was observed in 93% of the treated ears. Imiquimod treatment promoted the clearance of EcPV in 71.4% of the treated ears. Clinical remission of the aural plaques and changes in EcPV DNA positivity between the first and second biopsies were not observed in the control group. In 75% of horses, sedation was required in order to carry out pretreatment cleaning. Conclusions The results of this study support the hypothesis that 5% imiquimod cream may be used as an effective treatment for aural plaques in horses.