Q. I have a mare due to foal March 15. I dewormed her Jan. 9 with ivermectin. Should I deworm her again before she foals, and, if so, with which product?

—Via e-mail

A. I typically would not recommend deworming your mare again until she foals. The day a mare foals, we administer the dewormer ivermectin. This is to stop the streak of the parasite Strongiloides westeri (threadworms), which actually travels from the mare into the mammary gland and through the milk into the foal. A dose of ivermectin on the day of foaling will kill any parasites remaining and this will help prevent this parasite as a cause of early foal diarrhea.

Find more information from Dr. Ryan Ferris about preparing for breeding season and foaling in our Ask TheHorse Live: Get Ready for Equine Breeding Season!