FDA Clears Over-the-Counter Nitenpyram for Pets After New World Screwworm Found in Texas and New Mexico

U.S. Food and Drug Administration approved emergency use of over-the-counter generic Nitenpyram Tablets to treat New World screwworm infestations in dogs, puppies, cats and kittens that weigh at least two pounds and are at least four weeks old. The approval follows detections of the parasite in cows and goats in Texas and in one dog in New Mexico.

U.S. Department of Agriculture. The first case this month was found in the umbilicus of a three-week-old calf in Texas.

Nitenpyram is the first animal drug available to treat New World screwworm, the FDA said. Acting FDA Commissioner Kyle Diamantas said the agency spent nearly a year fast-tracking reviews and readying for the arrival of New World screwworm in the United States.

The New World screwworm is a parasitic fly species that feeds on the tissue or flesh of warm-blooded animals and people, the Centers for Disease Control and Prevention said.

Adult female flies lay 200 to 300 eggs at a time in open wounds and body openings such as the eyes, nose, mouth or genitals. Nitenpyram works quickly, killing most larvae within hours of the first dose, the FDA said. A second dose should be administered six hours after the first.

Dosage amounts are based on the pet’s weight. Because the effects are short-acting, Nitenpyram Tablets do not prevent NWS myiasis or protect against reinfestation, the FDA said. Following treatment, a veterinary professional may need to physically remove any remaining live or dead larvae.

A poster with information on the New World Screwworm was displayed during a press conference with government officials at the Texas Division of Emergency Management State Operations Center on June 5, 2026, in Austin, Texas.