Control of clinical coccidiosis of calves due to Eimeria bovis and Eimeria zuernii with toltrazuril under field conditions.

The efficacy of metaphylactic treatment with toltrazuril (Baycox 5% suspension) against natural infections with Eimeria bovis and/or Eimeria zuernii in calves was investigated. The study was conducted with 208 calves on five calf-rearing farms in Germany and the Czech Republic. All participating farms had a notable incidence of coccidiosis. Animals were treated 14 days after stabling in the respective facility. One group was treated with 15 mg toltrazuril/kg body weight, and a second group served as the sham-treated control. Assessment of efficacy was based on faecal consistency and oocyst excretion of E. bovis and E. zuernii, both investigated throughout the study. Duration and rate of oocyst excretion as well as number of scour days with E. bovis or E. zuernii oocyst shedding and the severity of diarrhoea were significantly lower in the toltrazuril-treated groups. It is concluded that a single metaphylactic treatment with toltrazuril controls coccidiosis of housed calves under various field conditions.