New World Screwworm Is in the US: How To Protect Your Pets

Lisa Selvaggio
by Lisa Selvaggio

Now that there have been confirmed cases of New World screwworm in the United States, specifically in Texas and New Mexico, including farm animals and a dog, pet parents are encouraged to become aware of the risks of infection and the steps they can take to protect their pets.

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New World screwworm (NWS) is a parasite that affects wildlife, livestock, and pets, and can also infect people. The fly lays its eggs in body orifices and wounds, and when the eggs hatch, the larvae feed on healthy surrounding tissue.  


Treatments for NWS in Pets


The good news is there are treatments available from veterinarians if your pet is diagnosed with NWS.


In 2025, because of the risk of NWS in the U.S., the FDA issued an Emergency Use Authorization (EUA) for Credelio CAT and also issued an EUA for Credelio for dogs.


Then, in February 2026, the FDA issued two Emergency Use Authorizations for NexGard for dogs and NexGard COMBO for cats infected with New World screwworm.


In June 2026, the FDA issued yet another EUA for generic nitenpyram to treat NWS infestations in puppies, dogs, kittens, and cats.


What to Look For


Because NWS larvae infect open wounds, check your pet’s skin every day to ensure you promptly and properly treat any wounds that occur, especially if you live in a high-risk area. Ensuring wounds are clean and heal well may help prevent NWS.


Cuts, sores, scrapes, hot spots, and abrasions are a few examples of what to look for. Letting your veterinarian know about these wounds is a good idea, as they can provide guidance on how to ensure they heal properly. Also, let your veterinarian know about any wounds that aren’t healing like they should.


If there is an NWS infection, you might see the larvae in your pet’s skin. Experts also advise seeking veterinary care if you notice symptoms like foul-smelling wounds, lethargy, restlessness, lesions, or your pet licking or biting their wounds. 


Left untreated, an NWS infection can be fatal, as the larvae destroy the tissue that surrounds the wound. So, don’t delay seeking veterinary care even if you only suspect your pet might be infected.


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Lisa Selvaggio
Lisa Selvaggio

Lisa Selvaggio is a freelance writer and editor, and our resident cats-pert, with certifications in pet nutrition and pet first aid. She enjoys producing content that helps people understand animals better so they can give their pets a safe and happy home.

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