FDA Authorizes Drugs for New World Screwworm in Dogs and Cats

FDA CVM Veterinary Medicine Updates

Published February 18th, 2026

Detected March 12th, 2026

Summary

The FDA has issued two Emergency Use Authorizations (EUAs) for NexGard and NexGard COMBO for the treatment of New World screwworm infestations in dogs and cats, respectively. These EUAs are effective until the HHS Secretary terminates the public health emergency declaration for this pest.

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What changed

The U.S. Food and Drug Administration (FDA) has issued two Emergency Use Authorizations (EUAs) for veterinary drugs to treat New World screwworm (NWS) infestations in pets. The first EUA is for NexGard (afoxolaner) chewable tablets for dogs and puppies, and the second is for NexGard COMBO (esafoxolaner, eprinomectin, and praziquantel topical solution) for cats and kittens. These authorizations are based on the FDA's conclusion that the drugs may be effective and that their benefits outweigh their risks for treating NWS myiasis. The EUAs remain in effect until the HHS Secretary terminates the declaration of a public health emergency related to NWS.

While NWS has not been detected in the U.S. as of February 18, 2026, pets near the U.S.-Mexico border or those that have traveled to affected regions are at higher risk. Both NexGard and NexGard COMBO are prescription-only medications, requiring veterinary oversight due to potential adverse neurologic reactions associated with isoxazoline drugs. Veterinarians and pet owners should consult detailed fact sheets for practitioners provided by the FDA. Regulated entities, specifically drug manufacturers and veterinarians, should be aware of these new treatment options and their associated conditions for use.

What to do next

Veterinarians should review FDA fact sheets for NexGard and NexGard COMBO regarding New World screwworm treatment.
Prescribing veterinarians must ensure appropriate monitoring for potential adverse reactions associated with isoxazoline drugs.
Pet owners should consult with their veterinarian to determine the suitability of these treatments for their pets.

Source document (simplified)

February 18, 2026

Today the U.S. Food and Drug Administration issued two Emergency Use Authorizations (EUAs) – one for NexGard (afoxolaner) chewable tablets for the treatment of New World screwworm (NWS) infestations (myiasis) in dogs, and the second for NexGard COMBO (esafoxolaner, eprinomectin, and praziquantel topical solution) for the treatment of NWS myiasis in cats.

For NexGard, the agency has concluded that based on the scientific evidence available, it is reasonable to believe that NexGard may be effective in the treatment of NWS myiasis in dogs and puppies, and the known and potential benefits of the product outweigh its known and potential risks.

For NexGard COMBO, the agency has concluded that based on the scientific evidence available, it is reasonable to believe that NexGard COMBO may be effective in the treatment of NWS myiasis in cats and kittens, and the known and potential benefits of the product outweigh its known and potential risks.

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.

As of February 18, 2026, NWS has not been detected in the United States. Most dogs and cats in America are at low risk of NWS due to their geographic location; however, pets near the U.S.-Mexico border and pets that have traveled to countries with active NWS cases are more likely to be exposed to NWS.

NexGard and NexGard COMBO are available only by prescription from a licensed veterinarian because professional expertise is required to monitor for and respond to potential adverse reactions. Detailed product information about NexGard for veterinary practitioners can be found in the Fact Sheet for Veterinarians: Emergency Use Authorization of NexGard (afoxolaner) Chewables for New World Screwworm (NWS) for dogs. Detailed product information about NexGard COMBO for veterinary practitioners can be found in the Fact Sheet for Veterinarians: Emergency Use Authorization of NexGard COMBO (esafoxolaner, eprinomectin, and praziquantel topical solution) for New World Screwworm (NWS) for cats.

Afoxolaner, the active ingredient in NexGard, and esafoxolaner, one of the active ingredients in NexGard Combo, belong to a class of antiparasitic drugs called isoxazolines. Although isoxazoline products are commonly used and safe for most pets, the products have been associated with neurologic adverse reactions, including muscle tremors, ataxia, and seizures. Pet owners should consult with a veterinarian to determine whether NexGard or NexGard Combo may be appropriate for their pet.

In addition to the EUA, NexGard chewable tablets are FDA-approved for flea and tick-related indications in dogs and puppies. NexGard COMBO topical solution is FDA-approved for flea, tick, and worm-related indications in cats and kittens.

NexGard and NexGard COMBO are sponsored by Boehringer Ingelheim Animal Health USA, Inc. based in Duluth, Georgia.

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