Comparing the Performance of McMaster, FLOTAC and Mini-FLOTAC Techniques in the Diagnosis of Strongylid Infections in Two Horse Populations in Portugal

The diagnosis of gastrointestinal (GI) strongyle infections in equids is still mainly performed using quantitative coprological techniques, like the McMaster (McM), but more sensitive and precise techniques, like FLOTAC (FL) and Mini-FLOTAC (MF), have been proposed over the past 20 years. The present study aimed to compare the analytical performance of these three methods in the diagnosis of strongyle infections in horses. Between October 2023 and June 2024, 32 fecal samples were processed using the McM, FL and MF techniques to identify strongyles' eggs, estimate their shedding (eggs per gram of feces, EPG), standard errors, sensitivities, precisions, and perform Spearman's correlation and Cohen's kappa analyses. The McM detected a higher shedding (584 ± 179 EPG), in comparison with FL and MF, with both these differences being statistically significant (<i>p</i> < 0.001); FL achieved the highest precision (72%), which differed significantly from McM (<i>p</i> = 0.03). All techniques were positively (r_s = 0.92-0.96) and significantly (<i>p</i> < 0.001) correlated and shared substantial (k = 0.67-0.76) and significant (<i>p</i> < 0.001) agreement. The MF achieved the highest diagnostic sensitivity (93%), followed by FL (89%) and McM (85%), although not significantly (<i>p</i> = 0.90). These results suggest the usefulness of implementing FL or MF methods in equine medicine for precise and, in the latter case, quick parasitological diagnosis.