New Standards for FECRT
The fecal egg count reduction test (FECRT) remains the method of choice for establishing the efficacy of dewormers in the field, including the diagnosis of dewormer resistance. The World Association for the Advancement of Veterinary Parasitology (WAAVP) recently established new guidelines for improving methodology and standardization of the FECRT for ruminants, horses, and swine.
The new guidelines are divided into four sections. Compared to the previous FECRT recommendations, four important differences are noted. First, it is now generally recommended to perform the FECRT based on pre- and post-treatment fecal egg count (FEC) of the same animals, rather than on post-treatment FEC of both treated and untreated (control) animals. Second, instead of requiring a minimum mean FEC (expressed in eggs per gram, EPG) of the group to be tested, the new requirement is for a minimum total number of eggs to be counted under the microscope (cumulative number of eggs counted before the application of a conversion factor). Third, there is flexibility in the required size of the treatment group by presenting three separate options that depend on the (expected) number of eggs counted. Finally, the guidelines address all major livestock species, and the thresholds for defining reduced efficacy are adapted and aligned to host species, dewormer drug, and parasite species.