The FDA Cleared Bravecto to Treat Screwworm. It Is Still a Prescription.

The Food and Drug Administration issued an emergency use authorization on Nov. 3 for Bravecto chewable tablets to treat New World screwworm infestations in dogs and puppies. The authorization went to Intervet Inc., the Merck Animal Health subsidiary based in Rahway, New Jersey, and carries the agency's file number EUA 006767.

Bravecto's active ingredient is fluralaner, and the drug was already approved for fleas and ticks. What the emergency authorization adds is a label that names the parasite. That distinction matters more to a veterinarian than to a pharmacist: until this month, a clinic treating a dog with maggots in a wound was reaching for an approved product on the strength of published evidence and clinical judgment, not a federal authorization covering myiasis specifically.

The Texas counties under screwworm movement restrictions have not changed with the announcement. The Texas Animal Health Commission's notice, checked Nov. 4, lists Brewster, Crockett, Culberson, Edwards, El Paso, Hudspeth, Jeff Davis, Jim Hogg, Pecos, Presidio, Reeves, Schleicher, Starr, Sutton, Terrell, Val Verde and Zapata. Warm-blooded animals may not leave those zones without prior authorization, an inspection and a movement or treatment certificate naming the product used.

The FDA's own framing is deliberately unalarmed. Most dogs in the country are at low risk, the agency said, because confirmed cases sit in a limited geographic region. The dogs that warrant attention are those that live in, travel to, or come back from areas where state or federal animal health officials have identified infestations, plus certain countries south of the border. Owners should watch for visible maggots or a foul odor from wounds and from body openings, eyes, ears, nose and mouth among them, and get an infested dog to a veterinarian immediately.

Why the prescription requirement survived an emergency order is the part worth reading twice. Fluralaner belongs to the isoxazoline class, which the FDA describes as commonly used and safe for most dogs, and also as associated with neurologic adverse reactions including muscle tremors, loss of coordination and seizures. Catching those reactions takes a clinician, so the tablets stay behind the counter.

Bravecto is the fourth isoxazoline to clear the FDA for this parasite. Lotilaner, sold as Credelio by Elanco, was first, authorized in October 2025. Afoxolaner arrived as a NexGard authorization in February, and sarolaner, combined with moxidectin and pyrantel in Simparica Trio, followed in August. Between those, the agency authorized generic nitenpyram tablets over the counter in June and then Capstar in September, when it also revised the generic authorization to cover prevention as well as treatment, the first emergency-authorized prevention option for dogs and cats. Bravecto's authorization is for treatment only.

The emergency authority behind all of this is not permanent. It runs until the FDA revokes it or the Health and Human Services secretary ends the declaration, published in the Federal Register on Aug. 20, 2025, that a screwworm emergency justifies authorizing animal drugs for the parasite.

Texas Public Radio reported Nov. 3 that confirmed cases across Texas, New Mexico and Arizona had reached 99. That figure is the outlet's count of federal and state reporting, not an agency release, and the totals have moved by a handful every few days since June.

For a pet owner in an infested county, the practical change is narrow and real: the next dog with an infested wound has a federally authorized treatment its veterinarian can reach for, with a documented safety caveat attached. For the response as a whole, the bottleneck is unchanged. A drug only helps after someone finds the wound, which on a pasture in Presidio County or the back of a hunt club lease still means a person, a horse and a flashlight. The research money now going into remote detection is aimed at exactly that gap, and it is two years from producing a field tool.