Resistance of gastrointestinal nematodes of sheep to some anthelmintics.

The occurrence of resistance to three of commonly used anthelmintics, Pyrantel tartrate (Banminth), Albendazole2.5% (Valbazen) and Duramectin 1% (Dectomax) was studied in locally bred sheep in Kafr El Sheikh Governorate, Egypt, by means of faecal egg count reduction test (FECRT). The faecal egg count reduction test showed that Pyrantel tartrate and Albendazole were less than 95% effective, 77% and 89% FECR% value respectively (i.e.: presence of resistance) while Duramectin showed full efficacy, 100% FECR% value. Culture of faecal samples before and after treatment in groups was done to interpret the anthelmintic resistance of individual nematode species. Where Ostertagia circumcincta and Bunostomum trigonocephalumn were susceptible to Pyrantel tartrate and Albendazole (100% FECR for each) but Nematodirus battus and Homonchus contortus have developed varying degrees of resistance for both drugs (56.3%, 48.2% and 88%, 70% respectively). Meanwhile, all nematode species were susceptible to Duramectin.