Efficacy of albendazole and fenbendazole against Giardia infection in cattle.

Efficacies of albendazole and fenbendazole in suppressing Giardia cyst output of infected calves were evaluated in two clinical trials. In the first trial, 18 naturally infected calves were allocated to an untreated control group (n = 9) and an albendazole-treated group (n = 9). Calves in the treated group were given 20 mg/kg-1 oral albendazole once daily for 3 days. Compared to controls, treated calves showed 98.5%, 97.6% and 90.8% reductions in cysts per gram of feces (cpg) 1, 2 and 6 weeks respectively after the start of treatment. In a second trial, 13 infected calves were allocated to an untreated control group (n = 6) and a fenbendazole-treated group (n = 7). Calves in the treated group were given 10 mg kg-1 fenbendazole orally twice daily for 3 days. Compared to the control group, treatments reduced cpg counts by 100%, 98.5% and 59.5% 1, 2, and 3 weeks respectively after the start of treatment. Both albendazole and fenbendazole appeared to be effective in suppressing cyst excretion by Giardia-infected calves.