DIAGNOSIS OF ANTHELMINTIC RESISTANCE IN CATTLE
Autor(es): José Henrique das Neves, Nadino Carvalho, Alessandro Francisco Talamini do Amarante
DIAGNOSIS OF ANTHELMINTIC RESISTANCE IN CATTLE
» Área de pesquisa: HELMINTOLOGIA
» Instituição: Faculdade de Medicina Veterinária e Zootecnia de Botucatu - FMVZ
» Agência de fomento e patrocinadores: Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The occurrence of anthelmintic resistance to levamisole, albendazole, ivermectin and moxidectin was investigated in cattle from ten farms located in São Paulo State, using two techniques for counting eggs in faeces: McMaster with a sensitivity of 50 eggs per gram (EPG) and FLOTAC with a sensitivity of 2 EPG. We also evaluated the use of different mathematical and test design approaches to determine the efficacy of the anthelmintics. Treatment groups received either: ivermectin (0.2 mg/kg of body weight (BW); moxidectin (0.2 mg/kg BW); albendazole (2.5 mg/kg BW); levamisole (4.7 mg/kg BW); or control (not treated). Faecal samples from each animal were collected two days before the treatment and again 10 and 28 days post treatment. The FEC reduction (FECR) confidence intervals were always wider when based on data obtained using the McMaster method than those obtained with the FLOTAC method. Excepting albendazole in one farm and levamisole in another farm, in general, these anthelmintics showed high efficacy against GIN. In contrast, ivermectin proved to be totally ineffective. Cooperia spp. was the major parasite displaying resistance followed by Haemonchus spp. The results also indicated the presence of Oesophagostomum spp. and Trichostrongylus spp. with resistance to ivermectin. Only 3 of the 10 farms had used moxidectin previously, but 9 of them showed the presence of gastrointestinal nematodes (GIN) with resistance to this drug. In conclusion, anthelmintic resistance to macrocyclic lactones were present in all herds evaluated. In surveys for anthelmintic resistance in cattle, the use of diagnostic method with higher sensitivity to detect eggs is recommended, as is the case of FLOTAC method. This study indicates that by using techniques (FLOTAC) with high sensitivity and testing the same animals pre- and post-treatment good precision can be achieved with group sizes from8 to 11 and without a control group.
