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

In an attempt to control natural infection of calves with coccidia of the genus Cryptosporidium Tyzzer, 1910, sulphadimidine was administered to calves aged 1 to 10 weeks prophylactically as a 2 I drench at a daily dose of 30 mg/kg body mass for two 7-day courses seven days apart or at a daily dose of 40 mg/kg body mass for 14 and 7 days at an interval of 6 days or therapeutically as a 1 I 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 cryptosporidia infection, occurrence of diarrhoea and gains in body mass.In the herd under study the proportion of calves shedding cryptosporidia was rather high but the cryptosporidial burden was low.The predominant picture was light infection with irregular shedding of oocysts without clinical sings of disease.Besides cryptosporidial oocysts, faecal examination revealed cysts of flagellates of the genus Giardia Ktinstler, 1882.Cryptosporidium, Giardia, calf diarrhoea, body mass gain, flotation methods.