PARSIPPANY, N.J., August 13, 2026
Zoetis Inc. announced that the U.S. Food and Drug Administration has issued an Emergency Use Authorization (EUA) for Simparica Trio® (sarolaner, moxidectin, and pyrantel chewable tablets) for the treatment of infestations caused by New World screwworm (Cochliomyia hominivorax) larvae in dogs and puppies. The authorization provides veterinarians with an additional tool to respond to a parasite that can cause severe tissue damage, pain and potentially death in affected animals. New World screwworm larvae feed on living tissue, including tissue around open wounds, and the expanding threat has increased the need for rapid detection and effective treatment strategies for companion animals and livestock.
Simparica Trio Gains Emergency Use Authorization for Screwworm
Under the FDA authorization, Simparica Trio can be used to treat New World screwworm infestations in dogs and puppies during the period covered by the emergency declaration. The company emphasized that the EUA applies specifically to this emergency use and that Simparica Trio is not FDA-approved for New World screwworm treatment under its standard approval. Simparica Trio is otherwise approved for dogs and puppies for prevention of heartworm disease and for treatment and control of several intestinal parasites, fleas and ticks. The monthly chewable combines sarolaner, moxidectin and pyrantel, providing broad parasite protection in a single administration. Zoetis said the new authorization could help veterinarians and pet owners respond more effectively as New World screwworm remains a concern in the United States.
Zoetis Expands Multi-Species Screwworm Response
The Simparica Trio EUA expands Zoetis’ animal-health response to New World screwworm beyond livestock and into companion animals. The company also offers Dectomax®-CA1 Injectable, a parasite-control product used for prevention and treatment of New World screwworm infestations in certain cattle populations. The FDA has separately authorized Dectomax and Dectomax-CA1 for specified emergency uses involving dairy cattle, swine, sheep, deer and horses. Early detection and rapid intervention remain important because screwworm larvae can rapidly damage living tissue. Zoetis said its coordinated approach across companion animals and livestock reflects a broader One Health strategy for addressing emerging and transboundary animal-health threats..
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FDA Authorization Adds Tool for Veterinarians and Pet Owners
The EUA gives veterinarians another option when managing dogs and puppies exposed to Cochliomyia hominivorax infestations. Zoetis advises pet owners to work closely with veterinarians when they observe suspicious wounds, maggots or possible infestations. Simparica Trio also carries important safety considerations, including caution in dogs with a history of seizures because sarolaner belongs to the isoxazoline class, which has been associated with neurologic adverse reactions such as tremors, ataxia and seizures. Vomiting and diarrhea were among the most frequently reported adverse reactions in clinical trials, and safe use has not been evaluated in breeding, pregnant or lactating dogs. The FDA EUA represents an important expansion of emergency treatment options, while continued surveillance and rapid veterinary assessment remain essential in managing New World screwworm threats.
Source: Zoetis ,press release
