The U.S. Food and Drug Administration has conditionally approved the nation’s first drug for the prevention and treatment of New World screwworm infestations in cattle, marking a significant step in protecting U.S. livestock from a dangerous parasitic threat.

The injectable solution, Dectomax-CA1 (doramectin injection), received conditional approval last week for use exclusively in cattle. The drug prevents and treats New World screwworm larval infestations and protects against reinfestation for up to 21 days.

FDA Commissioner Marty Makary, M.D., M.P.H., said the decision reflects the agency’s commitment to helping farmers and ranchers combat the pest, which can cause severe wounds and death in livestock.

“We understand the urgency with which America’s farmers and ranchers are asking for tools to fight New World screwworm,” Makary said in a news release. “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.”

The conditional approval allows Dectomax-CA1 to be marketed while its sponsor, Zoetis of Kalamazoo, Michigan, continues gathering data for full approval. Timothy Schell, Ph.D., acting director of the FDA’s Center for Veterinary Medicine, said the agency 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,” Schell said. “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-CA1 shares the same active ingredient and dosage as Dectomax, a drug already fully approved for treatment and control of certain nematode and arthropod parasites in cattle and swine. Because the FDA had previously reviewed safety and manufacturing data for Dectomax, new information was not required for those aspects of Dectomax-CA1’s approval.

The withdrawal period for treated cattle remains 35 days, identical to Dectomax. The FDA cautioned producers not to use Dectomax-CA1 in female dairy cattle 20 months of age or older and noted that no withdrawal period has been established for preruminating calves. The drug should not be used in calves intended for veal processing.

Dectomax-CA1 will be sold in 250 mL and 500 mL bottles, and its label will list indications for both Dectomax and Dectomax-CA1 under separate application numbers.

To help prevent antiparasitic resistance, the FDA and Zoetis urged veterinarians and producers to use the drug only when necessary, in line with label instructions and as part of a broader parasite management plan.

For more information, visit www.fda.gov.