The U.S. Food and Drug Administration conditionally approved Dectomax-CA1 (doramectin injection) injectable solution for the prevention and treatment of New World screwworm larval infestations, and prevention of NWS reinfestation for 21 days. Dectomax-CA1 is conditionally approved for use only in cattle.
According to Zoetis, this conditional approval applies to beef cattle, female dairy cattle less than 20 months of age, pregnant beef cows, newborn calves and bulls.
“We understand the urgency with which America’s farmers and ranchers are asking for tools to fight New World screwworm,” said FDA Commissioner Dr. Marty Makary. “Today’s conditional approval – the first in the U.S. for NWS – shows our dedication to rapidly advancing important animal medicines when they are needed most. We continue to work tirelessly to complete review of other NWS products to protect multiple animal species in the U.S.”
“New World screwworm has the potential to bring unprecedented economic and animal health harm to livestock producers,” said Mike Lormore, DVM, MS, MBA, Director of Cattle and Pork Technical Services at Zoetis. “Our top priority is to support keeping animals healthy and provide timely, efficacious solutions to our customers and partners. With this conditional approval, Dectomax-CA1 Injectable can now be used as part of safe, effective control measures against New World screwworm.”
The FDA says that Dectomax-CA1 is eligible for conditional approval because it is intended to prevent and treat a serious or life-threatening disease in cattle, it addresses an unmet animal health need, and demonstrating effectiveness of the drug would require complex or particularly difficult studies.
“Under this conditional approval, the FDA has determined the drug is safe and has a reasonable expectation of effectiveness. We are making this treatment available to cattle producers immediately while the sponsor collects the data needed for a full approval,” says Timothy Schell, Ph.D., acting director of the FDA’s Center for Veterinary Medicine. “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.”
Dectomax is already fully approved under a New Animal Drug Application for treatment and control of certain nematode and arthropod parasites in cattle and swine. Dectomax and Dectomax-CA1 contain the same active ingredient (doramectin injection) at the same dose. Because the original approval of Dectomax included adequate target animal safety studies, manufacturing information and human food safety information, FDA did not require new information to support those aspects for the conditional approval of Dectomax-CA1.
The withdrawal period for cattle is 35 days for Dectomax-CA1, as it is for Dectomax. Warnings to prevent drug residues in meat from treated cattle are the same for Dectomax-CA1 as for Dectomax: Not for use in female dairy cattle 20 months of age or older. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal.
“New World screwworm has the potential to bring unprecedented economic and animal health harm to livestock producers,” says Mike Lormore, DVM, MS, MBA, director of cattle and pork technical services at Zoetis. “Our top priority is to support keeping animals healthy and provide timely, efficacious solutions to our customers and partners. With this conditional approval, Dectomax-CA1 Injectable can now be used as part of safe, effective control measures against New World screwworm.”
In the first half of 2026, producers and veterinarians will begin to see the 250-milliliter and 500-milliliter bottles of Dectomax Injectable with a new label for Dectomax-CA1 (doramectin injection). Dectomax-CA1 is the same effective doramectin formulation as Dectomax Injectable.
Livestock producers are encouraged to work closely with their herd veterinarian to implement strategic prevention and control measures.
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FDA/Zoetis
