FDA issues EUA for product to treat New World screwworm in canine and feline patients

The FDA announced it has granted emergency use authorization (EUA) to afoxolaner chewable tablets (NexGard; Boehringer Ingelheim) for treating New World screwworm (NWS) myiasis in canines, and esafoxolaner, eprinomectin, and praziquantel topical solution (NexGard COMBO; Boehringer Ingelheim) for treating NWS myiasis in felines.

According to the FDA announcement, it concluded that based on the scientific evidence available, Nexgard is reasonable for the agency to believe to be an effective treatment option of NWS myiasis in dogs. Because of its known and potential benefits, it outweighs the known and potential risks. The agency concluded for NexGard COMBO that based on the scientific evidence available, it is reasonable to believe that the product may be effective for treating NWS myiasis in cats.

“These EUAs will be effective until they are revoked or the HHS secretary terminates the declaration that the potential public health emergency presented by NWS justifies the emergency use authorization of animal drugs for NWS,” the FDA stated in the announcement.¹

There have been no cases of NWS detected in the United States as of February 18, 2026, and most dogs and cats are low risk of NWS because of their geographic location. However, pets living near the US-Mexico border as well as any pets that have traveled to countries with active cases are more likely to be exposed to NWS.¹ Each product is only available by prescription from a licensed veterinarian due to the fact professional expertise is required to monitor for and respond to any potential adverse effects.

Along with NexGard and NexGard COMBO, the FDA has issued EUAs for the following products for treating or preventing NWS in multiple species^2-5:

• Ivermectin injectable solution (Ivomec 1%; Boehringer Ingelheim Animal Health)
• Fluralaner topical solution (Exzolt Cattle-CA1; Intervet Inc)
• Otilaner chewable tablets (Credelio Cat; Elanco Animal Health)
• lotilaner (Credelio; Elanco Animal Health)

Afoxolaner, NexGard’s active ingredient, and esafoxolaner, one of the active ingredients in NexGard COMBO, are isoxazoline, which is a class of antiparasitic drugs. Isoxazolines are commonly used and safe for most pets, but the products have been linked with neurological adverse reactions such as ataxia, muscle tremors, and seizures. Any pet parent interested in finding out whether these products are appropriate for their pet should consult with their veterinarian.

“Screwworm infestations can escalate quickly, and treatment delays put animals at real risk,” said Steve Maschmedt, executive director, Pet Veterinary Technical Services, Boehringer Ingelheim, in an organizational release.⁶ “Having authorized treatment options available enables veterinarians to respond quickly when NWS infestations are suspected. Flea and tick control remains important as well. Routine flea and tick control helps minimize skin irritation and small bite-related wounds, which can otherwise create opportunities for NWS flies to lay eggs.”

References

1. FDA issues emergency use authorization for drugs to treat New World screwworm in dogs and cats. News release. FDA. February 18, 2026. Accessed February 18, 2026. https://www.fda.gov/animal-veterinary/cvm-updates/fda-issues-emergency-use-authorizations-drugs-treat-new-world-screwworm-dogs-and-cats?utm_medium=email&utm_source=govdelivery
2. Crossley K. NWS preventive drug for cattle receives FDA emergency use authorization. dvm360. February 5, 2026. Accessed February 18, 2026. https://www.dvm360.com/view/nws-preventive-drug-for-cattle-receives-the-fda-s-emergency-use-authorization
3. McCafferty C. FDA conditionally approves topical drug for cattle to prevent and treat New World screwworm. dvm360. December 4, 2026. Accessed February 18, 2026. https://www.dvm360.com/view/fda-conditionally-approves-topical-drug-for-cattle-to-prevent-and-treat-new-world-screwworm
4. Bautista-Alejandre A. Antiparasitic receives FDA emergency authorization to treat New World screwworm in cats. dvm360. November 21, 2025. Accessed February 18, 2026. https://www.dvm360.com/view/antiparasitic-receives-fda-emergency-authorization-to-treat-new-world-screwworm-in-cats
5. Bautista-Alejandre A. FDA grants emergency use authorization for lotilaner to treat New World screwworm in dogs. dvm360. October 24, 2025. Accessed February 18, 2026. https://www.dvm360.com/view/fda-grants-emergency-use-authorization-for-lotilaner-to-treat-new-world-screwworm-in-dogs
6. Boehringer Ingelheim granted emergency use authorization for New World screwworm treatments in dogs and cats. News release. Boehringer Ingelheim. February 18, 2026. Accessed February 19, 2026. https://www.boehringer-ingelheim.com/us/animal-health/companion-animals-horses/pets/new-world-screwworm-emergency-use-authorization-dogs-and-cats