Descriptive Study of Medication Usage and Occurrence of Disease and Injury During Gestation in Thoroughbred...

The study aimed to (1) describe the use of reproductive therapeutics; (2) estimate the incidence of disease and injury; and (3) describe non-reproductive medications administered during pregnancy in Thoroughbred broodmares. A prospective birth cohort was established on seven farms across the UK and Ireland. Details of dams' signalment, breeding history, reproductive management during the breeding season(s) and veterinary-attended episodes of illness or injury and medication usage during gestation were retrieved retrospectively for 275 pregnancies in 235 mares over two breeding seasons. Results are reported at pregnancy-level of mares with data available. Preoestrus medications, ovulatory agents and post-covering treatments were administered to 55% (n = 85/155, 95% Confidence interval (CI) 47-62), 64% (n = 101/157, 95% CI 57-71) and 73% (n = 109/150, 95% CI 65-79) of mares respectively. Antibiotics were utilized in 69% (n = 75/109, 95% CI 60-77) of post-covering treatments. Of mares with no visible fluid on post-covering ultrasound, 37% (n = 24/65, 95% CI 26-49) still received treatment. Thirty-four percent (n = 70/203, 95% CI 28-41) of mares suffered at least one veterinary-attended episode of disease or injury, with conditions affecting the musculoskeletal system (23%, n = 46/203, 95%CI 17-29) and placentitis (5%, n = 10/203, 95% CI 3-9) most prevalent. Forty-seven percent (n = 95/203, 95% CI 40-54) of mares received at least one non-reproductive medication during gestation, antibiotics (25%, n = 51/203, 95% CI 20-31) and non-steroidal anti-inflammatory drugs (23%, n = 47/203, 95% CI 18-29) being most frequently prescribed. Post-covering treatments often included antibiotics and were sometimes given in the absence of fluid, highlighting a need to further understand therapeutic rationale. Disease occurrence and medication usage during gestation were frequent and warrant additional investigation.