A longitudinal study of fractures in 1488 Thoroughbred racehorses receiving intrasynovial medication: 2006-2011.

The research studied the relationship between intrasynovial medication and fracture risk in Thoroughbred racing horses from 2006 to 2011, finding that horses that had received three or more previous injections had a higher likelihood of sustaining a fracture within 56 days.

Objectives of the Study

• The intent of the research was to investigate potential associations between intrasynovial medication, a treatment where drugs are injected directly into the joint of a horse, and fracture risks in Thoroughbred racehorses.
• The research aimed to quantify the proportion and type of fractures that occurred following the administration of the intrasynovial medication.

Methods of the Study

• The researchers adopted a retrospective longitudinal study method to carry out the research. They reviewed clinical records of all Thoroughbred racing horses that received intrasynovial medication between years 2006 and 2011.
• The fractures that were sustained pre and post the medication were categorized by their location, type, and severity. Special focus was given to fractures that occurred within 56 days of administration of the medication.
• Survival analysis using Cox proportional hazards models were conducted to identify associations between factors such as medication type used (corticosteroid vs non-corticosteroid), age at first medication, sex, and total number of medications and their impact on fractures.

Results of the Study

• From 2006 to 2011, about 1488 horses received intrasynovial medication where 8692 synovial spaces were medicated in 3925 sessions.
• There were 96 fractures that occurred within 56 days of the medication. Out of these, 44 were classified as ‘serious’ and 11 horses had to be euthanised because of the severity of the injury.
• About 56.4% (54 of 96 cases) of the horses returned to racing. Only 7 of the 96 horses had imaging of the injury site prior to the injury post-medication.
• Horses that had three or more prior intrasynovial medication sessions encountered greater risks of sustaining a fracture within the 56-day window compared to those receiving three or fewer medication sessions.

Conclusion of the Study

• The researchers concluded that 3% of horses suffered from serious musculoskeletal injury following the administration of intrasynovial medication.
• The study suggests that a reduction in injury rates might be achievable through a more widespread use of premedication diagnostic imaging.