Antihelmintic Resistance For Gastrointestinal Bovine Nematodes

Abstract

The gastrointestinal nematodes (GIN), in domestic animals, especially in bovines are a very important factor that affects their productivity, because cattle production systems have intervened in the relationship between gastrointestinal parasites (PGI) and the host, breaking therefore the ecological balance between them. In many opportunities the development of parasitic populations have been favored or a parasitic population have been led to extinction, it has made that these populations express genes that would not express under normal conditions, favoring thus, resistance to medications that were made to their destruction. NGI are highly important in all cattle exploitations, but their inappropriate handling, mainly in the pharmacological aspect, has created vermifuge resistance by some parasitic populations. This article will determine the importance of the vermifuge resistance in cattle exploitations, as a factor of risk for the control of parasitic populations. The most important antihelmintic groups used in bovine are Benzimidazoles, Levamisol and Ivermectine and with these products resistance has been reported by parasitic populations such as in Haemochus contortus, Trichostrongylus. colubriformis, Ostertagia circumcicta, Ostertagia ostertagi. Different risk factors were classified in extrinsic (which don’t depend on the gastrointestinal parasite) and intrinsic (which depend directly on gastrointestinal parasites related with genetics) which occupy a great importance in the development of the vermifuge resistance.