Relationship of biosecuriy practices with the use of antibiotics for the treatment of infectious disease on U.S. equine operations

This study is the first report estimating, on a national basis, the use of various biosecurity practices, singly and in combination, on U.S. equine operations. Use of biosecurity practices is described for operations by risk level, based on reported exposure of resident horses to outside horses during the previous 12 months. In addition, the association between use of various biosecurity practices and use of antibiotics to treat infectious disease in both adult equids and foals is reported. The comparison of these study findings with previously reported data in the literature is limited by the fact that few estimates of biosecurity practice use on equine operations have been reported and none has been published on a national basis beyond those in the National Animal Health Monitoring System (NAHMS) equine reports. A total of 78.5% of operations had some risk of exposure of resident horses to outside horses between summer 2004 and the time of the interview in summer 2005. For the majority of biosecurity practices, there was a significant (p<0.05) difference between different exposure risk levels in the percentage of operations using the practice. A higher percentage of high- and medium-risk operations implemented a combination of 4 or more biosecurity practices compared to low-risk operations. There was less use of antibiotics to treat infectious disease in adult horses on operations that required those who visit the operation to use separate equipment, change clothes/overalls, disinfect boots and equipment, or park vehicles away from animals than on those that did not. None of the other biosecurity practices were associated with use of antibiotics in adult horses and none of the biosecurity practices included in this study was associated with use of antibiotics in foals. For adults the use of antibiotics for infectious disease increased with decreasing herd size; this trend was reversed for antibiotic use in foals. The effect of exposure risk level was different for adults and foals. For adults, antibiotic use was lower for operations at higher risk; for foals, antibiotic use was higher for operations at higher risk.