Analysis of morbidity and mortality data in riding school horses, with special regard to locomotor problems.

The incidence of disease, mortality and survival of horses, focusing on locomotor problems, at riding schools were studied, using data from an animal insurance database during 1997-2002. In total 5140 horses from 136 riding schools were included in the analysis. The overall yearly incidence rate (IR) was 1584 events of veterinary care per 10,000 horse-years at risk (HYAR). The total and diagnostic mortalities were 790 and 763 deaths per 10,000 HYAR. Rates varied substantially among riding schools. For locomotor problems the rates were 1116 events of veterinary care and 524 deaths per 10,000 HYAR. Multivariable Cox proportional-hazards analysis was performed on horses enrolled in insurance during the study period, including riding schools as frailty effects. For the outcome veterinary care for locomotor problems, the hazard ratios (HR) increased with increasing life-insurance value and Swedish warmbloods and other horses had increased HR compared to ponies. In the model with outcome life claim because of locomotor problems the breed groups Swedish warmblood and other horses also had higher HR than ponies. Age at entry > or = 8 years was associated with decreased HR for settled life-insurance cases due to locomotor problems and the two highest categories for insurance value had increased HR compared to the two lower categories. In the model with the outcome life claim because of previously claimed locomotor problems Swedish warmbloods had a higher HR than other horses and ponies. The HR increased by 33% for each year of age at entry. In south-urban areas of Sweden the HR was decreased compared to in all other areas, including baseline. Overall riding schools utilised the insurance more compared to all horses in the insurance database ( approximately 22% for the veterinary-care insurance and approximately 79% for the settled life insurance).