Equine tapeworms (cestodes) require an intermediate host to mature. Tapeworm eggs are ingested by the “orabatid” mite that lives on the blades of grass in pastures. Horses ingest the mites (and the tapeworm eggs inside the mites) while they graze. Inside the horse, the tapeworm eggs mature into adult tapeworms that attach to the intestinal lining.
Packets of eggs break off from the tapeworm and are passed out in the horse’s faeces, where they are ingested by pasture mites and the cycle starts again. Unfortunately, because of the sporadic way in which tapeworms release their eggs, the routine faecal test is not a reliable means of determining whether a horse is infected.
Tapeworms release little packets of eggs at intermittent times, so there is a only a small chance of finding them in a faecal sample although that is not to say they will not show up in a faecal floatation test from time to time so Tapeworm eggs (with its familiar “D” shape) are occasionally found during the routine faecal exam.
For a more accurate Tapeworm test we recommend the Equisal saliva test available separately.