FDA Clears Drug to Treat Screwworm in Pets

A nasty livestock parasite just triggered a first-of-its-kind pet drug move from the FDA. The agency on Thursday granted emergency authorization for an over-the-counter generic tablet to treat New World screwworm in dogs and cats—its first generic animal drug cleared to fight the flesh-burrowing pest, the Hill reports. The step follows at least seven confirmed screwworm cases in Texas and New Mexico involving cattle, a dog, and a goat, the first domestic detections in decades

The nitenpyram tablets, given by weight in two doses six hours apart, kill most larvae within hours but don't prevent new infestations; vets may still need to extract remaining worms. In a news release, the FDA said evidence shows the treatment is effective in "certain dogs, puppies, cats, and kittens, and the known and potential benefits of the product outweigh its known and potential risks." Health Secretary Robert F. Kennedy Jr. said the move gives pet owners a relatively low-cost, rapid option and bolsters efforts to contain the parasite's spread.

Kennedy said the government is "moving aggressively to contain and eliminate New World screwworm." Authorities fear the pest, which had been steadily moving toward the border since cases were discovered in southern Mexico in 2024, could devastate the cattle industry, along with deer populations. Edward Burgess, a University of Florida entomologist, tells the AP that more cases will probably be detected soon, but that doesn't necessarily mean the fly is spreading quickly. "When that first case is seen, everyone is being vigilant and their eyes are on it more intensely," Burgess says. "And when you are looking for something, you are more likely to see it."