The Food and Drug Administration (FDA) today issued an emergency use authorization (EUA) for a generic drug, nitenpyram, to treat New World screwworm (NWS) in dogs and cats. Nitenpyram, the first generic animal drug authorized for use against screwworm, can be used in animals who weigh at least two pounds and are at least 4 weeks old.
The FDA based the authorization on “the totality of the scientific evidence available,” noting that “the known and potential benefits of the product outweigh its known and potential risks,” the agency said in a statement. The FDA has issued 10 EUAs and three conditional approvals for drugs to combat NWS, a number that could grow as drugmakers submit additional applications.
“The FDA has spent nearly a year fast-tracking reviews and readying for the arrival of New World screwworm in the US,” Acting FDA Commissioner Kyle Diamantas said in the statement.
The US Department of Agriculture has confirmed seven cases of screwworm in cattle, a goat, and a dog. Although the first six animal infestations were in Texas, the dog is from New Mexico, raising fears of a widening outbreak.
Public health and animal health experts have been on alert for the larvae of the parasitic fly, which has sickened 27,449 animals in Mexico since November 2024, along with 141 people.
Increased risk for pets in areas with confirmed cases
Although most dogs and cats are at low risk of NWS, pets who live near areas with confirmed cases have a higher risk.
Caused by the larvae of the Cochliomyia hominivorax fly, NWS is a serious threat to livestock, wildlife, pets, and, in rare cases, people. The larvae (maggots) burrow into the living tissue of any warm-blooded animals, causing severe wounds and infections, and infection can be fatal.
Nitenpyram kills most NWS larvae within hours of the first dose. Pet owners should administer a second dose six hours after the first. Nitenpyram tablets do not protect against reinfestation.
After treatment, a veterinarian may still need to physically remove any remaining live or dead larvae, according to the FDA. The agency cautions pet owners against trying to remove the larvae themselves, to reduce the risk of infection or damaging tissue. Pet owners should ask their vet about wound care and how to reduce the risk of new infestations.
Nitenpyram tablets, sponsored by Felix Pharmaceuticals Pvt Ltd in Ireland, are sold over the counter. Dosages are based on a dog’s or cat’s weight.
The American Veterinary Medicine Association has created a website to help veterinarians recognize and treat NWS infestations in pets. The website advises vets to report any potential cases to state or federal animal health officials.
