Estudo retrospectivo de achados radiográficos no exame de compra de equinos da raça puro sangue inglês e sua correlação com a longevidade e o desempenho atléticos

Abstract

Locomotor conditions are the most frequent causes of discontinuity of horses´ training and performance. Radiology is the most used noninvasive technique for the identification of bone diseases in horses due to its portability and economic viability. The aim of this study was to investigate bone maturity and prevalence of radiographic abnormalities (RA) in Thoroughbred horses between 18 and 24 months of age, raised and commercialized in Brazil, prior to the beginning of training, and to correlate bone maturity and radiographic abnormalities with longevity and athletic performance. Radiographic images obtained through direct digital radiology between 2012 and 2015 were evaluated by two experienced veterinarians. In study 1, 286 radiographic images obtained in dorsopalmar view of the left carpus were evaluated. The distal epiphysial closure stage of the radius was evaluated and classified in A, B or C. The results were submitted to regression analysis and adjusted to linear and quadratic models. In the study 2, purchase exams of 100 horses with at least 18 radiographic projections were evaluated. The radiographic studies were classified as without (G1) or with radiographic abnormalities (G2), and had their anatomical location described. To each of the RA observed, a severity score was assigned that summarized forming an individual general severity radiographic score (IGSRS). The horses on G2 were separated by IGSRS in 3 groups. To investigate the prevalence and anatomical location of the RA, a descriptive statistical study of frequency was performed with comparison by chi-square test. The multivariate discriminant analysis technique was used to evaluate the significance of the group separation. All animals had their athletic performance obtained, including both qualitative and quantitative information, and a control group was formed of 100 different animals from those evaluated in groups 1 and 2. The severity scores of the RA on G2 were correlated to the horses´ athletic performance. All the data obtained were analyzed considering the level of statistical significance of 95%. The linear regression demonstrates the influence of age at first start over the total number of races and over the duration of the athletic campaign in months. Of the 100 animals evaluated in the study 2, 7% did not present RA while 93% presented RA. Of the 645 RA observed, 75.97% had a severity radiographic score of 1. The most prevalent RA were the changes detected on the proximal sesamoid bones in the thoracic and pelvic limbs. Horses that ran for the first time between 30 and 35 months of age and had a frequency of participation in races of approximately once a month had the most enduring athletic campaigns. The most prevalent radiographic abnormalities detected on purchase exams were in the metacarpophalangeal region, being mostly of a low degree of severity. The presence of moderate to severe radiographic abnormalities on the radiographic purchase exam of Thoroughbred foals at 18 months of age, decreased the duration of the athletic campaign and the athletic performance.