Use of infrared thermography to detect inflammation caused by contaminatedgrowth promotant ear implants in cattle

Objective-To compare the infrared thermographic appearance of bovine ears t hat had received contaminated growth promotant implants with ears that had received clean implants and ears without implants. Design-Prospective study. Animals-32 yearling crossbred beef steers with a mean weight of 322 kg (708 Ibs). Procedure-Contaminated (n = 16) and clean (16) implants were placed in the ears of feedlot cattle. Nonimplanted (n = 32) ears served as a within-anima l control for thermographic comparisons. Images of rostral and cauda( surfa ces were obtained during a 21-day period, using an infrared thermal imaging radiometer. Repeated measures ANOVA was used to determine the relationship between mean temperature in a zone on the rostral surface of the ear and a t 3 locations (proximal, middle, distal) on the caudal surface of the ear ( response variables) with treatment tears with contaminated implants or clea n implants vs control ears with no implants), time (repeated day of measure ment), and interactions among these variables. Results-Significant temperature differences existed between ears with conta minated implants and control ears. Temperatures for ears with clean implant s were significantly higher than control ears on day 2. At low ambient temp eratures when the ears became wet, a greater temperature contrast was detec ted between ears with contaminated implants and control ears. Conclusions and Clinical Relevance-Thermal imaging of the ears of feedlot c attle is a noninvasive diagnostic tool that can be used to identify cattle with abscesses caused by contaminated growth-promotant implants.