Factors influencing recovery from and duration of lameness in Michigan (USA) horses.

The objective of this study was to identify factors that may affect recovery from and duration of a case of lameness in a stratified random sample of Michigan horses. This was done using data from Phase-II of the Michigan equine monitoring system (MEMS Phase-II), the equine health-monitoring study [Kaneene et al., Prev. Vet. Med. 29 (1997b) 277-292; Ross and Kaneene, Prev. Vet. Med. 28 (1996a) 209-224; Ross and Kaneene, Prev. Vet. Med. 29 (1996b) 59-75; Ross et al., Am. J. Vet. Res. 59 (1997) 23-29]. In this study, statistical modelling was conducted to evaluate risk factors affecting recovery from and duration of lameness using multivariable logistic regression and Cox's proportional hazards regression, respectively. Of 357 incident lameness cases reported during MEMS Phase-II, 280 (78.6%) were reported to have recovered. The median duration of a lameness case was 18 days (1st quartile (Q): 1, maximum (Max): 360). A total of 296 of 357 (82.9%) incident lameness cases received some type of treatment. Of 619 total treatments used, 329 (53.2%) were administered, conducted or applied by a veterinarian. Horses experiencing other types of lameness were less likely to recover than those experiencing hoof lameness (odds ratio (OR) = 0.48; 95% CI: 0.25, 0.93). Horses that had participated in exercise-related activities during the study period and prior to the lameness were more likely to recover (OR = 1.91; 95% CI: 1.05, 3.50). Treatment of the lameness was associated with an increased likelihood of recovery (OR = 1.82; 95% CI: 0.97, 3.45). Cases with a veterinarian involved in the diagnosis were associated with a decreased risk of recovery (OR = 0.48; 95% CI: 0.27, 0.84) and a longer duration lameness (HR = 0.58; 95% CI: 0.45, 0.73)--which might indicate that these cases were more complex or severe. Although cases treated for lameness were more likely to recover (OR = 1.82; 95% CI: 1.05, 3.50), treatment was not associated with lameness duration (HR = 0.58; 95% CI: 0.45, 0.73).