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Merck gets US FDA emergency use nod for treatment of screwworm in dogs

By Thomson Reuters Nov 3, 2026 | 3:13 PM

Nov 3 (Reuters) – The US Food and Drug Administration on Tuesday issued an emergency use authorization for Merck’s Bravecto tablets to ​treat New World screwworm in dogs and ‌puppies, expanding treatment options to combat the parasite.

Here are more details:

• The agency said most dogs in the US remain at low risk because confirmed cases are limited ‌to ​a restricted geographic area

• However, ⁠dogs living in, traveling ⁠to, or returning from affected regions should be monitored for signs of infestation, including visible maggots or foul-smelling wounds, it added

• The FDA ​said it concluded, based on available scientific evidence, that it is reasonable to believe Bravecto ⁠may be effective in ⁠treating screwworm infestations and that its ​potential benefits outweigh its risks when used as authorized

• ​The FDA issues emergency use authorizations to ‌allow the use of unapproved treatments during public health threats when no alternatives are available

• Bravecto, whose active ingredient is fluralaner, is already approved ⁠for certain flea- and tick-related uses in dogs and puppies

• The drug belongs to a class of antiparasitic ⁠medicines called isoxazolines, ‌which have been associated with ⁠neurological side effects such as muscle ​tremors, loss ‌of coordination and seizures, the FDA ​added

• The ⁠agency said the drug will remain available only by prescription through a licensed veterinarian

• The FDA issued the authorization to Intervet, Merck’s US animal health unit

(Reporting by Siddhi Mahatole in Bengaluru; Editing by ​Leroy Leo)