Equimax Receives FDA Approval for Pregnant and Nursing Mares

The broad-spectrum dewormer Equimax (also labeled for tapeworms) recently received FDA approval for safety in pregnant and nursing mares. A French study confirmed the safety of ivermectin/praziquantel--the active ingredients in Equimax--for this use in December 2003 (www.TheHorse.com/ViewArticle.aspx?id=4765). However, for FDA approval, a U.S. study had to be completed to prove its safety and efficacy against U.S. pharmaceutical standards.

"There was nothing FDA-approved available for pregnant and nursing mares against tapeworms before Equimax received this approval," says Robert Dressler, DVM, manager of equine veterinary operations at Pfizer Animal Health, the product's manufacturer. "We (originally) were required by the FDA to put a warning label stating that it was not to be used in pregnant or nursing mares. Veterinarians and horse owners may have used the product on pregnant and nursing mares prior to approval--but it was not recommended by Pfizer."

The study performed to receive approval, done by Larry Cruthers, MS, PhD, of Professional Laboratory and Research Service, Inc., in Corapeake, N.C., involved 26 mares. The mares and their foals were healthy during and after the study, with no adverse affects on the mares' fertility.

Toxicosis as a result of ivermectin overdose has occurred in previous studies when the anthelmintic was administered at 10 times the recommended dose for two consecutive days. Signs of ivermectin toxicosis in the horse include transient vision impairment, depression, ataxia, and dehydration; none of these signs were detected in the study subjects.

About the Author

Marcella M. Reca Zipp, MS

Marcella Reca Zipp, M.S., is a former staff writer for The Horse. She is completing her doctorate in Environmental Education and researching adolescent relationships with horses and nature. She lives with her family, senior horse, and flock of chickens on an island in the Chain O'Lakes.

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