Occurrence of anthelmintic resistant equine cyathostome populations in Central and Southern Italy

In the present survey, 276 horses bred on 16 farms located in central and southern Italy were investigatedfor the presence of drug resistant cyathostomes by a Fecal Egg Count Reduction Test (FECRT). Sixteen to20 animals were selected on each farm and randomly assigned to one of four equally sized treatment groups.Groups were treated with fenbendazole, pyrantel pamoate, ivermectin or moxidectin. Resistance tofenbendazole was declared on six farms (37.5%) and suspected in two farms (12.5%), with FECR valuesranging from 41% to 88.3%. Resistance to pyrantel was found in two farms (12.5%) and was suspected inone case (6.2%), with FECR values ranging from 43% to 85.4%. Macrocyclic lactones remained effectiveon all farms. Only cyathostome third stage larvae (L3) were found in fecal cultures after treatment. Thispaper reports the first wide survey conducted in Italy for anthelmintic resistance in equine cyathostomes.The results indicate that multiple drug resistant equine cyathostomes are present in the central and southernregions of Italy. These data call for a geographically and numerically broader investigation of horse farms inall regions and for the development and implementation -among veterinarians, owners and managers of a plan to reduce the expansion of these anthelmintic resistant populations and control these importantparasites.[...]