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New World Screwworm in Texas: Latest Cases, Symptoms, and How to Help Protect Your Pets
A parasite that was eradicated from the United States decades ago has recently been detected in several Texas counties, prompting increased monitoring by animal health officials.
Known as New World screwworm, the parasite can infect livestock, wildlife, pets, and, in rare cases, people. While the current risk to most household pets remains low, Texas pet owners should understand what the parasite is, how it spreads, and when to seek veterinary care.
The SPCA of Texas is committed to helping pet owners stay informed about emerging animal health concerns. Here’s what we know about New World screwworm, the latest reported cases in Texas, and practical steps you can take to help keep your pets safe.
What We Know Today
Animal health officials continue to actively monitor and respond to confirmed New World screwworm cases in Texas.
Here’s what we know:
“The average pet owner in North Texas should be aware of the situation, but there’s no reason to panic,” said Dr. Valarie Tynes, Chief Veterinarian for the SPCA of Texas. “The best protection is what we already recommend every day: routine veterinary care, monthly parasite prevention, and prompt attention to wounds.”
What Pet Owners Need to Know
Despite its name, New World screwworm is not actually a worm. It is the larval stage of a fly.
The adult female fly lays eggs in open wounds or natural body openings of warm-blooded animals. When the eggs hatch, the larvae feed on living tissue. Unlike many common maggots that feed on dead tissue, screwworm larvae attack healthy tissue, causing painful and potentially life-threatening injuries if left untreated.
New World screwworm can affect:
“One of the reasons New World screwworm is taken so seriously is that the larvae feed on living tissue rather than dead tissue,” said Dr. Tynes. “That means even what appears to be a minor wound can become a significant medical problem if an infestation develops and treatment is delayed.”
Recent Confirmed Cases in Texas
While New World screwworm has received significant media attention, it is important to keep the current situation in perspective.
As of mid-June 2026, animal health officials have confirmed 11 cases in Texas across six counties: Zavala, La Salle, Gillespie, Edwards, Tom Green, and Sutton counties. Most of the confirmed cases have involved livestock, including calves, goats, and sheep.
The currently confirmed Texas cases have been concentrated in South and West Texas. No cases have been reported in North Texas at this time.
To put that into perspective, Texas is home to millions of dogs and cats. While any confirmed case is taken seriously, the number of affected animals remains extremely small relative to the state’s overall pet population.
“These confirmed cases demonstrate why surveillance is so important,” Dr. Tynes explained. “Early detection helps animal health officials respond quickly and can significantly reduce the risk of additional spread.”
For pet owners, the key takeaway is simple: monitor wounds carefully, keep pets on veterinarian-recommended parasite prevention, and seek veterinary care promptly if something does not look right.
The Latest Veterinary Updates
Veterinary researchers and animal health agencies across the country are closely monitoring the situation.
Recent developments include:
Increased Surveillance and Response Efforts
State and federal agencies have expanded monitoring, inspection, and containment activities in affected areas of Texas. Additional animal health personnel are being deployed to identify and respond to cases quickly.
New Treatment Option for Pets
The U.S. Food and Drug Administration recently issued an emergency authorization for generic nitenpyram tablets for the treatment of New World screwworm infestations in dogs and cats. The medication can kill larvae quickly, though veterinary care is still necessary to properly treat wounds and prevent complications.
Why Animal Welfare Organizations Are Paying Attention
While the currently reported Texas cases have primarily affected livestock, New World screwworm can impact multiple species.
“Animal health threats rarely affect only one species,” said Dr. Tynes. “Protecting animals requires a One Health approach that recognizes the connections among pets, livestock, wildlife, people, and the environment. That’s why animal welfare organizations, veterinarians, and animal health agencies are all paying close attention to this situation.”
Can Flea and Tick Prevention Help?
Some commonly prescribed flea and tick preventives contain medications from a class known as isoxazolines, including:
These medications have demonstrated activity against a variety of parasites and may provide additional protection if exposure occurs. However, they should not be considered a substitute for wound care, routine monitoring, or veterinary treatment.
“Keeping pets on veterinarian-recommended parasite prevention is always important, but pet owners should still check their animals regularly for injuries and seek prompt veterinary care for any wounds,” said Dr. Tynes.
Pet owners should consult their veterinarian about which preventive product is most appropriate for their individual pet.
What Pet Owners Should Watch For
Early detection is critical.
Contact your veterinarian immediately if you notice:
“Pet owners know their animals better than anyone,” said Dr. Tynes. “If a wound suddenly looks worse, has an unusual odor, contains visible larvae, or your pet seems uncomfortable or ill, contact your veterinarian immediately.”
Do not attempt to remove larvae or treat a suspected screwworm infestation yourself. Veterinary treatment is necessary to fully address the infestation and prevent additional damage.
How to Help Protect Your Pets
✔ Check pets regularly for cuts, scratches, hot spots, and skin irritation.
✔ Keep wounds clean and monitor them until fully healed.
✔ Stay current on veterinarian-recommended parasite prevention.
✔ Pay extra attention to pets recovering from surgery or injuries.
✔ Contact your veterinarian if a wound appears to worsen or heal slowly.
✔ Seek immediate veterinary care if you see larvae, unusual drainage, swelling, or foul odors around a wound.
Why This Matters
The reappearance of New World screwworm in the United States is a reminder that animal health threats can emerge quickly and affect pets, livestock, wildlife, and communities.
Fortunately, animal health agencies, veterinarians, researchers, and animal welfare organizations are working together to identify cases, contain the outbreak, and protect animals.
Texas pet owners do not need to panic, but staying informed is important.
“Awareness, routine veterinary care, and prompt attention to wounds are the best steps pet owners can take right now,” said Dr. Tynes.
Stay Informed
The SPCA of Texas will continue to monitor developments and share updates that may affect pets and animal welfare in our community.
For more pet health resources, animal care tips, and updates affecting Texas animals, visit SPCA.org and follow the SPCA of Texas on Facebook, Instagram, LinkedIn, and YouTube.
If your pet has a wound that concerns you or appears to be getting worse, contact your veterinarian promptly.
Because when it comes to protecting animals, early action can make all the difference.
About the Expert
Dr. Valarie Tynes, DVM, DACVB, DACAW, serves as Chief Veterinarian for the SPCA of Texas. She is board certified in both veterinary behavior and animal welfare and is among a small number of veterinarians in the United States to hold both certifications. Dr. Tynes earned her veterinary degree from Texas A&M University and has spent her career advancing animal welfare through clinical practice, behavior medicine, shelter medicine, and animal welfare leadership.
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