Survival analysis of risk factors associated with the occurrence of lameness in a Michigan horse population.

The study aimed to investigate lameness in horses from Michigan, United States, and identify risk factors associated with it. The findings revealed that horses in larger operations are less prone to lameness. Additionally, stallions and geldings exhibited a heightened risk, as did horses actively participating in performance-related activities such as racing and showing.

Research Methodology

• For the study, the researchers observed 3,925 horses from 138 randomly chosen operations in Michigan over a total period of 814,753 horse-days.
• Horses monitored for less than 60 days were excluded from the source population.
• Following these initial conditions, they generated a case-control study population that included all cases of lameness and a random sample of ‘noncases’, or horses without lameness.
• The researchers analyzed various risk factors associated with the occurrence of lameness using Cox’s proportional hazards regression model.

Results

• The study showed that horses in larger operations exhibited a lower rate of lameness than those in smaller operations. Indeed, horses in the largest operations (4th quartile) had a 46% lower risk compared to those in the smallest operations (1st quartile).
• Compared to mares, stallions and geldings were found to be at a higher risk of lameness. The risk was particularly elevated in stallions, who had a 90% increased risk of lameness.
• Active participation in exercise or performance-related activities like racing and showing was also associated with an increased risk of lameness. Horses involved in racing observed a staggering 370% increased risk, while those in show activities showed a 180% higher risk compared to horses used only for breeding purposes.

Conclusions

• The results indicated a lowered risk of lameness in horses residing in larger operations. Conversely, active horses and those classified as stallions and geldings exhibited a higher risk for this condition.
• In comparing these results with those obtained from multivariable logistic regression, the argument for decreased lameness risk in larger operations and increased lameness in active horses is strengthened.
• Based on these findings, it was proposed that lameness prevention strategies should focus on horses involved in exercise or performance activities, male horses, and horses stabled in smaller operations.