Attempted Therapy and Prophylaxis of Cryptosporidiosis in Calves by Administration of Sulphadimidine

Abstract

In an attempt to control natural Cryptosporidium infection of calves, sulfadimidine was administered prophylactically to calves aged 1-10 weeks as a 2-litre drench at a daily dose of 30 mg/kg for two 7-day courses seven days apart, or at a daily dose of 40 mg/kg for 14 and 7 days at an interval of 6 days, or therapeutically as a 1-litre drench at a daily dose of 200 mg/kg body mass for three 3-day courses, three days apart. These treatments had practically no effect on cryptosporidial infection, occurrence of diarrhoea or weight gain. In the herd under study the proportion of calves shedding cryptosporidia was rather high but the cryptosporidial burden was low. There was light infection with irregular shedding of oocysts and no clinical sign of disease. In addition to cryptosporidial oocysts, faecal examination revealed cysts of flagellates of the genus Giardia.