It is important to remember that all deworming protocols should weigh the likelihood of infection to the safety and efficacy of the medication. Risk of infection is based on environmental factors such as housing and geographic location, age of the animal, overall health status, and exposure to other animals. Efficacy of medication will be determined by the type of internal parasite, its location within the animal, and any suspected drug resistance.
The following protocol is a general suggestion for horses in the Pacific Northwest. We recommend having your horse examined annually by a veterinarian to establish a specific protocol based on your horse’s exposure and requirements.
Pregnant mares: De-worm with ivermectin or fenbendazole 14 days prior to foaling date.
Foals: De-worm with pyrantel at 6-8 weeks old; if after 10 weeks, give ½ dose followed in 1 week with full dose to avoid ascarid impaction.
Dogs: Many de-wormers are toxic to dogs; Be especially careful to properly dispose of any leftover medication and packaging.
Environmental measures that break the life cycle of internal parasites are as important as administering de-wormers. Follow good management practices to control the frequency and spread of internal parasites.
- Remove manure daily from stalls and weekly from pastures.
- Be sure pastures and paddocks are well-drained and not overpopulated.
- Compost manure rather than spreading it on fields where horses graze.
- Use a feeder for hay and grain and avoid ground feeding.
- Initiate effective fly control programs.