RESUMO
BACKGROUND: Radiological findings in the proximal sesamoid bones (sesamoids) are a persistent source of controversy at Thoroughbred sales, due to inconsistent classification and conflicting assignment of potential clinical importance. OBJECTIVES: To define the prevalence of sesamoid findings on sales repository radiographs in yearling and 2-year-old Thoroughbreds and to analyse associations with racing performance. To track the changes in sesamoid findings between 1 and 2 years of age in horses that present for sale at both ages. STUDY DESIGN: Prospective cohort study using an enrolled sample. METHODS: Horses were enrolled from a 2016 yearling sale and five 2017 2-year-old sales with consignor permission. Radiological findings relating to sesamoid vascular channel appearance, abaxial contour changes and sesamoid fragments were examined. Associations between sesamoid findings and racing performance from 2 to 4 years of age were examined using multivariate regression analyses. Clinical follow-up was sought to ascertain why horses that did not race never started. RESULTS: A total of 2508 yearlings and 436 2-year-olds were included for evaluation. Interobserver agreement using the new grading system was substantial. Yearling findings associated with a significantly reduced probability of starting a race were: Grade 3 vascular channels in forelimb sesamoids (0.52, P < 0.001, 95% confidence interval (CI): 0.37-0.67), abaxial new bone in forelimb sesamoids (0.62, P = 0.01, 95% CI: 0.49-0.73), apical or abaxial fragments in forelimb sesamoids (0.55, P = 0.005, 95% CI: 0.37-0.72). For affected horses that did race, Grade 3 vascular channels in forelimb sesamoids were associated with fewer race starts (9.9 starts, P = 0.03, 95% CI: 8.0-12.2) and Grade 3 vascular channels in hindlimb sesamoids were associated with a delayed start to racing careers (54 days, P = 0.01, 95% CI: 20-89). Abaxial new bone in forelimb sesamoids was associated with a 54% reduction in total earnings (P = 0.003, 95% CI: 24-72) and a 46% reduction in earnings per start (P = 0.002, 95% CI: 21-64). Abaxial concavity occurred predominantly in yearling medial forelimb sesamoids, had no impact on racing performance and mostly resolved by 2-year-old sale. MAIN LIMITATIONS: These findings are applicable to horses presented for sale at public auction and may underestimate the prevalence of severe lesions in non-sales horses. CONCLUSIONS: Grade 3 vascular channels, forelimb sesamoid abaxial new bone and forelimb sesamoid fragments are important findings in sales repository radiology. The new grading scale assigns a numerical grade for vascular channel appearance that matches the number of enlarged vascular channels evident in a given sesamoid. Abaxial contour changes, when present in sesamoids that are Grade 0 for enlarged vascular channels, are noted separately as either abaxial new bone or abaxial concavity. Fragments are also noted and interpreted separately.
RESUMO
BACKGROUND: To the authors' knowledge, the effect of a combination of butorphanol tartrate and detomidine hydrochloride on the laryngeal function and symmetry of the arytenoid cartilages in young Thoroughbred horses has not been examined. Therefore, this study aimed to examine the effects of administration of butorphanol and detomidine on left-to-right rima glottidis ratio (L:R RGR), cross-sectional area of the rima glottidis (CSARG) and grade of laryngeal function of Thoroughbred yearlings examined endoscopically at rest. METHODS: Forty-six Thoroughbred yearlings underwent laryngeal video endoscopy, at rest, before and after sedation with butorphanol and detomidine. Three clinicians assigned grades of laryngeal function after reviewing the video recordings. The L:R RGR and CSARG were measured at the point of arytenoid cartilages' maximal abduction. Student's t-test was used to compare the L:R RGR and CSARG. Cohen's kappa (κ) was used to compare the intra- and interobserver agreements. Spearman's rank order was used to assess agreement between CSARG and grade of laryngeal function. RESULTS: Sedation had no effect on L:R RGR and CSARG. Mean intraobserver agreement of grade of laryngeal function of unsedated yearlings was 93.1%, and that of sedated yearlings was 92.9%. Mean interobserver agreement of grade of laryngeal function of unsedated yearlings was 92.8%, and that of sedated yearlings was 92.7%. Correlation between CSARG and laryngeal function grade was significant for both groups (p < 0.001). CONCLUSION: Sedating Thoroughbred yearlings with detomidine and butorphanol, before endoscopically examining the larynx, did not significantly affect the grade of laryngeal function.