Detection of Equus caballus Papillomavirus in Equine Aural Plaque Samples.

Aural plaques have been linked to Equus caballus papillomavirus (EcPV). Ten types of EcPVs have already been described; however, only EcPVs 1, 3, 4, 5, and 6 have been observed in association with aural plaques. Accordingly, the objective of this study was to evaluate the presence of EcPVs in equine aural plaque samples. A total of 29 aural plaque samples (from 15 horses) were collected and assessed for the presence of the DNA of these EcPVs by PCR. Additionally, 108 aural plaque samples used in previous research were evaluated for the presence of EcPVs 8 and 9. Previously described primers were used for PCR to detect EcPVs 1 to 8, and specific primers were designed for EcPV 9. Minigenes were synthesized and used as a positive control in the PCRs for the undetected EcPVs. EcPVs 2, 7, 8, and 9 were not detected in any of the evaluated samples, suggesting that these viral types are not involved in the etiology of the equine aural plaque in Brazil. EcPV 6 was the most prevalent (81%), followed by EcPVs 3 (72%), 4 (63%) and 5 (47%), which reinforces the idea that these viruses play an important role in the etiology of the equine aural plaque in Brazil.

Frequency of Equus caballus papillomavirus in equine aural plaques.

Despite the reported association between aural plaques and the presence of Equus caballus papillomavirus (EcPV), there are few data regarding the distribution of viral types in different geographic regions or possible correlations for different papillomaviruses and lesion characteristics. We detected the presence and frequency of EcPV (1-7) DNA in aural plaque biopsies of horses from different regions of Brazil and identified the patterns of these infections or coinfections and their possible association with lesion severity. A total of 108 aural plaque biopsies from horses in the 5 geopolitical regions of Brazil were examined. We performed PCR to detect EcPV DNA in the biopsies. At least 1 type of EcPV was detected in 97% of the samples. EcPV coinfection was observed in 59% of the samples. Compared to the other viruses, EcPV-4 was found at the highest frequency in coinfection (84%) or individually identified (32%). EcPV-2 and -7 were not detected. No significant association was found between lesion characteristics (type and distribution) and either the viral type detected or the presence of coinfection. EcPV is widely distributed in Brazil, both isolated and in coinfection; the viral type does not appear to influence the clinical characteristics of equine aural plaques.

Factors associated with equine aural plaque in Brazil.

BACKGROUND: Aural plaques can be found on the inner surfaces of one or both ears of horses. Despite their low malignancy, these lesions can sometimes cause discomfort and sensitivity in horses, and a loss in commercial value due to their aesthetic effect. There has been a study describing the epidemiological features and the clinical prevalence of equine aural plaques in Brazil. HYPOTHESIS/OBJECTIVES: To determine the clinical prevalence and selected associated factors of aural plaques. ANIMALS: In the study, 891 horses were assessed for aural plaques. The sample group had a median age of 5 years and comprised both sexes and various breeds from different regions of Brazil. METHODS: Horses were evaluated by a general observation of the body and a detailed observation of both ears. Data on the management system, characteristics of the lesions, the presence of ticks and ear grooming were collected for 109 clinically affected horses. An assessment of the frequency distribution of the disease and its characteristics was performed. Association tests were conducted to establish the relationships between the variables studied. RESULTS: In 85% (40 of 47) of farms assessed, at least one horse presented with aural plaques. In 14.8% (132 of 891) of the horses, lesions characteristic of aural plaque were detected. Significant associations between the prevalence of "coalescing" lesions and a "semi-intensive" management system and ear grooming were detected. CONCLUSIONS: The findings confirm the extensive distribution of this disease in Brazil and its association with several management factors.

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.