Comparison of two fecal egg recovery techniques and larval culture for cyathostomins in horses

To compare the McMaster and centrifugal flotation techniques and larval culture for recovery of cyathostomin (small strongyle) eggs from the feces of horses. Fecal samples from 101 horses. In experiment I, homogenized fresh feces from a single horse were randomly subsampled by use of each technique for 10 replicates. In experiment II, samples from 43 horses that had no anthelmintic treatment were analyzed by use of McMaster, centrifugal flotation, and larval culture techniques. In experiment III, 57 horses were treated with an anthelmintic by owners, and fecal samples were analyzed as for experiment II. In experiment I, use of the McMaster technique recovered 72% of the eggs obtained by use of centrifugal flotation from paired subsamples. In experiment II, use of the McMaster technique recovered 81% of the eggs obtained by use of centrifugal flotation. Only cyathostomins resulted from individual larval cultures. In experiment III, 24 samples had negative results for all 3 tests, 18 samples had positive results only with larval cultures, and 15 samples had positive results of centrifugal flotation (only 5 of which had positive results via the McMaster technique). Centrifugal flotation consistently was superior to the McMaster technique, especially at low fecal egg numbers. The combination of centrifugal flotation and larval culture may provide the best accuracy for evaluation of anthelmintic efficacy.