Horse Worming Schedule: New AAEP Veterinary Guidelines (announced in 2009)

Why a new horse worming schedule? Despite rotation regimens, veterinarians are seeing more and more dewormer resistance—cases where the dewormer is no longer effective in clearing parasite infections. Routine worming schedules are vitally important for horse health, and constitute a cornerstone of quality horse care. For this reason, the American Association of Equine Practitioners (AAEP) recently released new deworming recommendations, as follows:

1. Conduct fecal egg count tests for all horses on your property. This is easy to do. You can purchase test kits on-line. All you do is put some of your horse's manure in a small vial, fill out the form, include a check (usually under $20), and mail it off. You'll receive your results in the mail in a week or so. Or you can have your veterinarian do the test for you.

2. Immediately deworm horses with positive test results (more than 100 eggs).

3. For horses with negative test results (100 eggs or less), deworm ONLY TWICE ANNUALLy with a dewormer that contains praziquantel and ivermectin (e.g., Zimecterin Gold or Equimax) or praziquantel and moxidectin (e.g., Quest, ComboCare). The first deworming should be during mid-fly season and the second during the winter freeze.

The reason you must still deworm with praziquantel is that bots and tapeworms don’t show up on fecal egg counts. Praziquantel is especially effective against these kinds of parasites.

If a horse is carrying a very heavy parasite load, it is best to deworm gradually because a large die-off of parasites can make a horse very ill. If your horse has a very high fecal egg count, consult your veterinarian before deworming him.

If you're boarding (or own a boarding facility), make sure that all new horses have been tested (and dewormed, if necessary) BEFORE they arrive on your property. A single horse carrying a high parasite load can shed hundreds of worms in your barn and pastures, which puts all the other horses at the facility at risk.

These new guidelines should help fight back against dewormer resistance. Return from horse worming schedule to successful horse training and care.