WASHINGTON, D.C. — In a significant achievement for American farmers and ranchers, the U.S. Food and Drug Administration (FDA) has given conditional approval to Dectomax-CA1, an injectable solution aimed at preventing and treating infestations of New World screwworm (NWS) larvae in cattle. This is the first time a drug targeting this harmful parasite has received approval in the U.S.
The newly sanctioned treatment, created by Zoetis and utilizing the active ingredient doramectin, provides both treatment and 21 days of protection against NWS reinfestation — a much-needed relief for livestock producers who are increasingly threatened by this aggressive flesh-eating pest.
“We understand the urgency with which America’s farmers and ranchers are asking for tools to fight New World screwworm,” said FDA Commissioner Marty Makary, M.D., M.P.H. “Today’s conditional approval shows our dedication to rapidly advancing important animal medicines when they are needed most.”
Why This Matters
New World screwworms, which deposit their eggs in the open wounds of warm-blooded animals, can inflict severe tissue damage and even lead to death if not treated. Outbreaks can cause significant economic losses throughout the livestock sector, particularly for cattle producers.
The conditional approval enables Dectomax-CA1 to be available right away, even as the company continues to collect additional data necessary for full FDA approval. Under this designation, the drug must prove its safety and a “reasonable expectation of effectiveness” — a criterion that Dectomax-CA1 meets due to the pressing need and the challenges of conducting large-scale studies on such infestations.
“The FDA will continue to expedite review of animal drugs to help the U.S. fight this devastating threat to our nation’s livestock and the livelihoods of the farmers and ranchers who care for them,” said Timothy Schell, Ph.D., acting director of the FDA’s Center for Veterinary Medicine.
About the Drug
- Product: Dectomax-CA1 (doramectin injection)
- Use: Treatment and prevention of New World screwworm larval infestations in cattle
- Availability: 250 mL and 500 mL bottles
- Withholding Period: 35 days before slaughter, not for dairy cows over 20 months or veal calves
- Manufacturer: Zoetis, based in Kalamazoo, Michigan
Dectomax-CA1 uses the same formulation as the original Dectomax — already approved for other parasites — which helped fast-track its approval due to existing safety and manufacturing data.
The FDA cautions veterinarians and producers to use antiparasitic drugs like Dectomax-CA1 only when medically necessary and as part of a broader parasite control strategy to help prevent resistance and preserve long-term effectiveness.
