Age, gender, and breed as risk factors for acute and chronic equine laminitis

Abstract

A prospective case-control study of risk factors for laminitis analyzed data of the 258 incident cases seen at six collaborating veterinary teaching hospitals over a 32-month period. Case-control pairs were matched on institution, clinician, and time of diagnosis. The 90% of case-control pairs (78 acute, 155 chronic) having complete data for age, gender, and breed were used in separate conditional logistic recession models for acute and chronic laminitis. The odds ratio was calculated for the three upper quartiles of age (referent lowest quartile); for mares and stallions (referent geldings); and for other breed categories (referent the Thoroughbred). Increasing age increased the risk of acute and chronic laminitis nonlinearly. Mares, but not stallions, were more likely than geldings to develop acute laminitis (OR 2.6. 95% CI 1.1-6.2) and chronic laminitis (OR 2.0, 95% CI 1.1-3.6). In the small acute laminitis data set the breed variable was collapsed into three categories, the Thoroughbred (THB), the Quarter Horse (QH), and Other (non-QH-THB). When compared to the referent category THB, the non-QH-THB group, but not the QH was at increased risk of acute laminitis (OR 3.8, 95%G 1.2-11.8). For the seven breed group categories used in the chronic laminitis model, however, all non-THB breeds appeared significantly at risk as compared to the THB, with ads ratios ranging from 3.3 (95% (71 1.3-8.30) for the QR to 9.1 (95% CI 2.1-39.3) for poles. In general, the results of this study agree with anecdotal evidence and the findings of prior studies, with the exception of no increased risk of laminitis seen in this study for stallions as compared to geldings. However, caution should be used in interpreting lese findings, because this referral population likely differed from Animals that would be seen in private practice, some of the breed categories encompassed multiple breeds, there were relatively few subjects in some of the breed categories, breed was confounded with the type of work or use, and most important, since the case and control series in this study may each have represented differing hospital catchment areas, the exposure breed may have been linked with outcome in this study.