FDA Emergency Authorization Covers Bravecto for Screwworm in Dogs

By Elena Vasquez

On November 3, 2026, the U.S. Food and Drug Administration issued an emergency use authorization for Merck Animal Health's Bravecto (fluralaner) chewable tablets to treat New World screwworm myiasis in dogs and puppies.

The action gives U.S. veterinarians another FDA-authorized option for an infestation whose larvae feed on living tissue of warm-blooded animals and whose complications can become fatal without rapid intervention.

The FDA concluded that available scientific evidence provided "a reasonable basis to believe" the medication may be effective and that expected benefits outweigh known and potential risks when used as authorized.

New World screwworm myiasis results from infestation with Cochliomyia hominivorax. Federal animal health officials are responding to a parasite capable of harming livestock, wildlife and companion animals, with occasional human involvement.

What changes for companion-animal practices?

For companion-animal veterinarians, the immediate change is treatment access. Bravecto is already widely used for flea and tick control; its active ingredient, fluralaner, belongs to the isoxazoline class of antiparasitic medications. Under the authorization, veterinarians may use the specified chewable tablet product according to FDA conditions to treat affected dogs and puppies.

Emergency authorization does not replace comprehensive veterinary management. Affected animals require prompt clinical assessment, appropriate wound management and additional supportive treatment as indicated by infestation severity. The established isoxazoline safety warnings still apply. Although these products are generally well tolerated, neurologic adverse reactions reported in some dogs include tremors, ataxia and seizures.

More treatment choice does not simplify comprehensive care.

How do veterinarians recognize screwworm?

Unlike many fly species that lay eggs in dead or decaying material, the New World screwworm fly deposits eggs in wounds or around body openings. After the eggs hatch, larvae burrow into living tissue. The resulting painful lesions can progress rapidly to extensive tissue destruction, secondary infections and potentially fatal complications.

Clinicians may find visible larvae within a wound, often with foul odor, swelling, pain and tissue damage. Infestations may also develop around the eyes, ears, nose, mouth or other body openings. Most U.S. dogs remain at low risk because confirmed detections are geographically limited, but dogs living in or traveling through affected areas require closer monitoring.

Early recognition remains essential when an unusual wound suggests exposure.

What does emergency authorization mean?

This FDA Center for Veterinary Medicine (FDA CVM) action is not conventional FDA approval for the added indication. It creates an FDA-authorized treatment option under defined conditions rather than a standard approval for the new use. Veterinarians must meet the authorization conditions for the specified chewable tablet product.

The announcement identifies no parallel European Medicines Agency (EMA) or U.S. Department of Agriculture (USDA) authorization for this Bravecto use.

This is emergency use, not conventional approval.

What are the food-animal and public-health implications?

Food-animal implications. Screwworm can disrupt agricultural operations because otherwise healthy animals can become infested through relatively small wounds. Untreated cases may cause substantial tissue destruction, reduced productivity and animal mortality.

The new Bravecto authorization covers dogs and puppies. FDA has already issued other emergency authorizations and conditional approvals for products intended to help prevent or treat infestations in various animal species; this action does not extend Bravecto's use to food animals.

Public-health implications. The parasite can affect livestock, wildlife, companion animals and, occasionally, humans. Veterinarians play a central role by identifying suspected cases, educating owners and coordinating with animal health officials when they find an infestation.

That role matters because infestations can progress rapidly, and early recognition and veterinary intervention remain essential. Surveillance also supports efforts to limit the parasite's impact.

Early action limits damage across sectors.

What should practices do now?

Small-animal teams should now take travel histories and unusual wound presentations more seriously during routine examinations, even though New World screwworm remains uncommon for most U.S. companion-animal veterinarians. Prompt assessment, wound care and supportive treatment remain the immediate priorities.

Teams should also educate owners to seek rapid evaluation of suspicious wounds and to provide relevant travel information when dogs live in or visit affected areas. Suspected cases should prompt coordination with animal health officials because early recognition, appropriate treatment and effective surveillance limit the parasite's impact.

Looking ahead, if confirmed detections expand beyond currently affected areas, early recognition and coordinated surveillance will become more important; the new treatment option cannot substitute for timely diagnosis.