Hemicastration in Chilean rodeo stallions in competition

Abstract: The objectives of this study were: a) establish the frequency, age and reason for hemicastration, b) determine the most frequently removed testicle and c) compare the athletic performance between unilaterally castrated and intact Chilean rodeo stallions. Two hundred and sixteen Chilean Horse stallions participating in the 2016 Chilean rodeo qualifying rounds and National Championship (CRNC) were evaluated. Owners and/or riders were interrogated about age, hemicastration, age at hemicastration, removed testicle, reason and effects of hemicastration on athletic performance of stallions. The statistical analysis was descriptive and the results were expressed in means and percentages. Chi-square test was used to compare the performance between unilaterally castrated and intact stallions. Performance was qualified based on qualification to the CRNC and ultimately participation in the Champion series. Fifty-three percent of the stallions were unilaterally castrated (47% left testicle; 53% right testicle) (P>0.05). Mean age of hemicastration was 6.97±2.24 years. Main reasons reported for hemicastration were: traumatic (76%), increased volume (13%) and preventive (11%), but not all of them with medical confirmation. Seven owners or riders were unaware of the reason of hemicastration. Forty-six percent of the qualified stallions to the CRNC (P>0.05) and 29% of the qualified to the Champion series were unilaterally castrated (P=0.0122). It was concluded that half of the 2016 elite Chilean Horse stallions were unilaterally castrated, without preference for a testicle, after the age of initiation of sporting activity. A 43.5% of hemicastration in Chilean rodeo stallions are performed preventively or based on subjective assessments of owners and riders without veterinary diagnosis, however, it is unclear that hemicastration affected the athletic performance in these cases.