Resistance anthelmintic in sheep in the region of Londrina- Parana State - Brasil

Abstract

Helmintosis is one of the main sanitary problems of modern sheep raising whereas the resistance to anthelmintic is a severe impend for its control. With the objective of verifying the phenomenon in relation to albendazole, ivermectin and moxidectin in the region of Londrina, Parana, Brazil, 850 animals from 10 properties were selected, from January to March 1997. These animals were distributed in four randomic groups, T1-albendazole, T2-ivermectin, T3-moxidectin and T4-control, and were monitored by the method of counting eggs by each gram of faeces in order to obtain the percentage of reduction in the average of gastrintestinal nematod's eggs. The results showed that anthelmintic resistance occurred in all properties with percentages of 100, 80 and 20% for albendazole, ivermectin and moxidectin, respectively. Through the analysis oflarvas's culture it was observed that Haemonchus spp. was the most frequent type of nematodes and, probably, the major reason for the resistance to the drugs used in the experiment.