FDA Authorizes Emergency Use of Drug for New World Screwworm in Dogs

The U.S. Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for Simparica TRIO, a medication containing sarolaner, moxidectin, and pyrantel chewable tablets, for the treatment of New World screwworm (NWS) infestations in dogs and puppies. This authorization provides a new treatment option for veterinarians and pet owners should animals become infested with the parasitic New World screwworm.

While most dogs in the United States currently face a low risk of exposure to New World screwworm due to their geographical location, owners should remain vigilant, particularly if their pets live in, travel to, or have returned from areas where NWS has been identified by animal health officials, or from certain countries south of the U.S. border. Signs of infestation can include visible maggots or an unpleasant odor emanating from wounds or body openings such as the eyes, ears, nose, or mouth. Prompt veterinary care is crucial if an infestation is suspected. Current confirmed detections of New World screwworm in the U.S. are limited to specific regions within Texas and New Mexico, according to the U.S. Department of Agriculture’s dashboard.

The FDA’s decision to authorize Simparica TRIO for this emergency use is based on scientific evidence indicating that the drug may be effective in treating New World screwworm myiasis in dogs and puppies when used as directed. The agency concluded that the potential benefits of the medication outweigh its potential risks. It is important to note that Simparica TRIO is authorized for treatment, not prevention, of New World screwworm infestations.

Pet owners are encouraged to stay informed about the situation and recognize the signs of infestation without causing undue alarm. Consulting with a veterinarian is advised if there are any concerns about potential exposure or infestation. Simparica TRIO, previously approved by the FDA in 2020 for other indications such as heartworm, flea, and tick prevention, contains sarolaner, an active ingredient in the isoxazoline class of antiparasitic drugs. While isoxazoline products are generally considered safe and effective for most dogs, they have been associated with rare neurological adverse reactions, including tremors, loss of coordination, and seizures. Due to the need for professional monitoring and management of these potential reactions, Simparica TRIO is available only by prescription from a licensed veterinarian. Veterinarians can help determine if Simparica TRIO is an appropriate treatment option for an individual dog.

The Emergency Use Authorization for Simparica TRIO will remain in effect until it is revoked by the FDA or the Secretary of Health and Human Services terminates the public health emergency declaration related to New World screwworm. Zoetis Inc., located in Kalamazoo, Michigan, is the sponsor of Simparica TRIO. Further detailed information for veterinarians and pet owners regarding this EUA, including potential adverse events associated with isoxazoline products, can be found in fact sheets and related documents available from the FDA.

Article by Mel Anara, based upon information from the U.S. Food and Drug Administration.

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