Deworming after a faecal egg count: selective deworming of horses
Today, adult horses are no longer dewormed by the calendar but by the result of a faecal egg count: a horse that sheds few eggs isn’t treated. That slows down resistance. The Friends4horses worm check assesses every faecal egg count according to the ESCCAP recommendation, plans the next one and checks after a deworming whether it worked. It is free and meant as guidance – the vet decides whether and with what to deworm.
For iPhone. The Android app isn’t on Google Play yet.
What is selective deworming?
With selective deworming, an adult horse only gets a dewormer if the faecal egg count suggests it. According to ESCCAP Germany, a horse is treated when more than 200 eggs per gram of droppings (EPG) of small strongyles are counted or when other intestinal parasites are detected. Regardless of the result, ESCCAP recommends at least one deworming a year.
- Only for adult horses. The app sets the limit at four years; for younger horses the vet’s plan applies.
- Roundworms, tapeworms and large strongyles are treated regardless of the egg count (Vetsuisse, parasite management in horses).
- A negative tapeworm result doesn’t rule them out – the eggs are only shed intermittently.
How often should a faecal egg count be done?
In the first year four tests, from April/May to October/November, then three a year (spring, summer, autumn). The app suggests the next test four months after the last one; three or six months can be chosen. The appointment then appears in the calendar and reminds you like any other.
Did the dewormer work? The faecal egg count reduction test
A second faecal egg count 10 to 14 days after deworming shows whether a product still works. The app compares it with the last test before deworming (up to 30 days before) and calculates by what percentage the egg count dropped. According to the AAEP guidelines, the expected drop is:
| Active ingredient | Minimum drop |
|---|---|
| Ivermectin, moxidectin, combination with praziquantel | 95% |
| Fenbendazole | 90% |
| Pyrantel | 85% |
If the drop is smaller, the app says “a sign of reduced efficacy” – a reason to talk to the vet. If the egg count was below 200 EPG before, the test is hardly meaningful, and the app says so too.
How do I enter a faecal egg count?
- In the health record, open the worm check (at the top of the deworming list).
- Enter the date and the egg count (EPG) from the lab report, and roundworms and tapeworms if the lab tested for them.
- The app assesses the test: no treatment needed, discuss with the vet or can’t be assessed.
- For a deworming, choose the active ingredient and have the follow-up check created – it goes into the calendar as a follow-up faecal sample appointment.
Dewormers can have a withdrawal period in horses intended for slaughter. You enter it on the deworming as the vet states it – more under Equine passport and withdrawal period.
Frequently asked questions
From how many eggs should a horse be dewormed?
According to the ESCCAP recommendation, an adult horse is treated when the faecal egg count shows more than 200 small strongyle eggs per gram of droppings (EPG) or when other intestinal parasites are detected. The vet makes the decision.
How often should a faecal egg count be done?
ESCCAP recommends four tests in the first year between April/May and October/November, then three a year. The app suggests four months between two tests; three or six months can be chosen.
Does selective deworming also apply to foals?
No. It only applies to adult horses. Young horses shed more eggs and carry roundworms; for them the vet’s deworming plan applies. The app sets the limit at four years and says so explicitly for younger horses.
Does a negative faecal egg count rule out tapeworms?
No. Tapeworm eggs are only shed intermittently, so the faecal egg count misses most infestations. Roundworms, tapeworms and large strongyles are treated regardless of the egg count.
Sources, as the app cites them: ESCCAP Germany, Recommendation No. 8 (control of endoparasites in horses); Vetsuisse Faculty Zurich/Bern, parasite management in horses (May 2020); AAEP Internal Parasite Control Guidelines (revised 05/2024). Not a diagnosis.