Resistencia antihelmíntica de nematodos gastroentéricos en ovinos a febendazol e ivermectina en la región noroeste del estado de Tlaxcala

Abstract

This experiment examined the problem of anthelmintic resistance in gastro-intestinal nematodes (GIN) to Ivermectin (IVM) and Febendazole (Fbz) in naturally infected sheep from Tlaxcala, Mexico. Twenty flocks were selected from three districts in Northern Tlaxcala: Calpulalpan (4), Nanacamilpa (10) and Hueytotlipan (6). Groups ranged from 10 to 14 sheep each and they were designed as follows: I), control, II) treated with Fbz at 5 mg per kg of body weight per os, and group (III) treated with IVM at 0.2 mg/kg of bodyweight by subcutaneous injection. Faecal samples were collected and nematode egg counting was estimated at days 0 and 14. Results were based on the faecal egg counts and from a flock management survey applied to farmers. The results showed that one flock was resistant to IVM, three flocks were classified as suspicious and sixteen flocks were susceptible. Moreover, infected sheep treated with Fbz did not show anthelmintic resistance, however, three flocks were suspicious and seventeen flocks were susceptible to this drug. On the other hand, the survey analysis showed that the frequency of anthelmintic treatments was 75 % to IVM, 65 % to Fbz and 45 % to Salicilanide. Besides, 55 % of experimental sheep were Merino-Dorset acquired from Australia, 75 % Suffolk, 10 % Hampshire, 10 % Cross-breed and 5 % Columbia, these last four breeds were acquired from local regions. Moreover, resistance to IVM appeared to be related to the frequent use of IVM and by infected sheep with GIN acquired from other regions.