Efficacy and safety of oral praziquantel against Dicrocoelium dendriticum in llamas.

Dicrocoelium dendriticum can cause severe pathological changes of the liver and bile system in camelids, and therapeutic options for treatment are limited. To address this problem, the efficacy of two different dose rates of praziquantel was investigated in llamas suffering from natural D. dendriticum infections. 53 llamas were examined under field conditions on two occasions: before and two weeks after treatment. At the beginning of the study, the animals were weighed, randomly allocated to one of the treatment groups (n=21 each) or the control group (n=11) and dosed orally using a praziquantel-containing paste (250 mg/ml) at a dose of either 25 mg (group 1) or 50 mg (group 2) per kg of body weight. Criteria for efficacy were faecal egg count reduction (FECR) and extensity effect. Animals treated with 25 mg/kg of body weight showed a FECR of 85%. Therapy with 50 mg/kg led to a FECR of 91%. Almost twice the number of animals of group 1 (33%) still shed eggs two weeks after treatment compared with group 2. The results of this study indicate that 50 mg/kg oral praziquantel is required for efficacious dosing and that this dose rate is safe in llamas and thus is recommended for the treatment of camelids naturally infected with D. dendriticum.