Evaluation of the dosage of tilmicosin for the treatment of acute bovine footrot (interdigital phlegmon)

Abstract

Two studies on a commercial feedlot in Western Canada investigated the dose of s.c. tilmicosin injection required for treating bovine foot rot. 320 animals with signs of acute lameness including inflammation and swelling of the skin and tissues of the interdigital cleft, coronet, and/or the distal limb were considered suspect cases of foot rot by pen riders and presented to the hospital for diagnosis. Candidates for enrolment were thoroughly examined to eliminate those cases of lameness caused by foreign objects, sprains, fractures, sole abscesses or other causes of lameness not associated with acute bovine foot rot. As animals presented they were randomly assigned to either placebo (saline at 1.5 ml/50 kg), 2.5, 5.0 or 10.0 mg tilmicosin/kg in blocks of 4 animals (study 1) or to either 2.5, 5.0 or 10.0 mg tilmicosin/kg in blocks of 3 (study 2). On day 1 (defined as the point in time that the animal is confirmed for inclusion on the trial and treatment administered), day 2, day 3 and day 4 the animals were scored for lameness, swelling and lesions using a 4 point scale. Treatment was considered successful if on day 4 the animal scored 0 (normal) for lameness and did not require retreatment for foot rot in the next 10 days. Cure rates were 15.0, 68.0, 74.0 and 77.0 %, respectively, for the placebo, 2.5, 5.0 and 10 mg tilmicosin/kg. There were no significant differences between the 2.5, 5.0 and 10 mg tilmicosin/kg doses but all were significantly (p<0.05) higher than the placebo. Efficacy appeared to be dose related.