FDA Authorizes Emergency Use of Ivermectin to Fight New World Screwworm in Horses

WASHINGTON, D.C — The U.S. Food and Drug Administration has issued an Emergency Use Authorization for ivermectin liquid for horses to help prevent New World screwworm infestations in horses, federal officials announced Thursday.

The authorization allows the prescription medication to be used for the short-term prevention of New World screwworm myiasis when administered within 24 hours of a horse's birth or during initial wound care. The FDA emphasized the product is authorized only for horses and is not approved for use in other animal species.

"The Trump administration will use every available tool to stop New World screwworm from threatening America's horses and livestock," U.S. Health and Human Services Secretary Robert F. Kennedy Jr. said. "This EUA expands our defenses, strengthens our preparedness, and helps protect the animals, producers, and communities that drive American agriculture."

U.S. Department of Agriculture Secretary Brooke Rollins said the authorization supports the Trump administration's broader effort to combat the pest.

"President Trump has directed his entire administration to do what it can to combat and stop the spread of New World screwworm," Rollins said. "Today's announcement is another step in the right direction."

New World screwworm is a parasitic fly whose larvae feed on the living tissue of warm-blooded animals. Newborn animals with healing umbilical wounds and animals with open wounds are especially vulnerable because adult flies are attracted to those areas to lay eggs. Left untreated, infestations can become severe and life-threatening.

The FDA said its review concluded there is sufficient scientific evidence to believe the product may be effective for short-term prevention of screwworm infestations in horses and that its potential benefits outweigh the known and potential risks.

Acting FDA Commissioner Kyle Diamantas said the authorization marks the agency's 11th emergency authorization issued to address the New World screwworm threat.

"The Trump administration is leaving no stone unturned in our fight to shield American ranchers, livestock producers, and the agricultural economy from this threat," Diamantas said.

Federal officials stressed the authorization applies only to prevention, not treatment. Horse owners whose animals already have an active screwworm infestation are advised to contact a veterinarian for appropriate treatment.

Timothy Schell, director of the FDA's Center for Veterinary Medicine, said horse owners should continue using other protective measures because the medication provides no more than 24 hours of preventive protection.

"This product's window of prevention lasts no more than 24 hours, so it is important that the product be used alongside other preventive measures such as bandaging, repellents, and other fly-control methods," Schell said.

Ivermectin liquid for horses is a ready-to-use oral solution that may be administered by oral drench or through a stomach tube. It is available only by prescription from a licensed veterinarian.

The emergency authorization will remain in effect until it is revoked or until the U.S. Department of Health and Human Services ends the public health emergency declaration related to New World screwworm.

The product is manufactured by Alberta Vet Labs Ltd., a Canadian veterinary pharmaceutical company.