Efficacy of the main anthelmintics used in the control of bovine flukes in warm and humid climate in Mexico

Fasciola hepatica and paramphistomids are common endoparasites in cattle. Chemical control is the main method to avoid the effects of both trematodes on herd health. This study aimed to evaluate the efficacy of the most commonly used anthelmintics against trematodes (paramphistomids and F. hepatica) in cattle raised in a warm climate in Mexico. Fecal samples were obtained from 393 cows that were naturally infected with F. hepatica and paramphistomids. The fecal egg count was determined using the sedimentation technique, recording the eggs per gram of feces (EPG). Only trematode-positive cows were used to assess anthelmintics such as nitroxynil (NITROX), triclabendazole (TCBZ), fenbendazole (FBZ), rafoxanide (RAFOX), albendazole (ABZ) and oxyclozanide (OCZ). Efficacy was determined following the WAAVP guidelines; samples were taken 15 days post-treatment to perform the fecal egg count reduction test (FECRT). According to FECRT, the efficacy of anthelmintics was 0–83.3% against paramphistomids and 51.8%–100% against F. hepatica. The most effective anthelmintics against F. hepatica were NITROX (89–100%) and RAFOX (93–100%). Triclabendazole in all its combinations (TCBZ + FBZ and ABZ) had lower efficacy in controlling paramphistomids (0–39%), but high efficacy against F. hepatica (59-73%). Most anthelmintics were effective against F. hepatica; however, control alternatives for paramphistomids require further investigation.