Texas vets warn pet owners about flesh-eating screwworm

Pets are now part of the warning

Texas veterinarians are warning pet owners to take New World screwworm seriously as the flesh-eating parasite moves from a livestock problem toward a broader animal-health concern in the Southwest. The latest reporting says the risk is no longer limited to cattle, goats and sheep. It now includes pets that spend time outdoors, especially animals with wounds or skin openings that could attract the fly.

Lori Teller, executive director of the Texas Veterinary Medical Association, told Axios that any pet spending time outside could be at risk. The parasite lays eggs in wounds, scratches, insect bites, surgical incisions and other openings in the skin. Once the eggs hatch, the larvae feed on living tissue.

That feeding behavior is what makes screwworm so dangerous. If an infestation is not treated quickly, the damage can worsen fast and can become severe enough to kill the animal.

How the outbreak reached this point

The current U.S. detections began with livestock in Texas in early June. Houston Chronicle reporting said the first Texas case was confirmed in a calf in Zavala County by the USDA's National Veterinary Services Laboratory. Texas officials then urged continued vigilance after what they described as the state's first case since 1966.

From there, the reporting moved from a single livestock case to a wider regional concern. Axios reported on June 24 that Texas had confirmed 15 animal cases, mostly in goats, cattle and sheep, and said a dog in Lea County, New Mexico, had also been diagnosed. The Guardian later reported 16 known animal cases in Texas, showing that the outbreak count is still moving as officials and journalists track new developments.

The different totals do not change the core picture: this is an active outbreak with ongoing surveillance, and the number of known cases is still being clarified.

What pet owners should watch for

Pet-owner guidance published by People on June 18 described the signs owners should not ignore. Those include wounds that worsen quickly, visible larvae, white egg masses, lethargy and loss of appetite. The symptoms can be easy to miss at first, especially in animals that roam, work outdoors or spend time near livestock.

That is why veterinarians are emphasizing early checks and rapid treatment. A wound that looks unusual, smells bad, enlarges quickly or seems more painful than expected should be examined promptly. Waiting at home is risky because screwworm larvae feed on living tissue and can spread damage as they grow.

Axios also reported that several flea and tick preventives prescribed for dogs and cats have FDA authorization to treat New World screwworm infestations. That does not mean every routine parasite medication will help, but it does mean some treatment options already exist if a veterinarian identifies the parasite early.

Why ranchers and farmworkers are worried too

The concern extends beyond pet owners. The Guardian reported that no human cases have been identified, but said the outbreak has raised concern for agricultural workers in the U.S. Southwest because they are more likely to encounter animals, open wounds and contaminated environments.

That risk is especially relevant in ranching areas, where livestock, outdoor pets and workers may all be in closer contact. The parasite's ability to infect through wounds means any animal or person handling potentially infested animals needs to be careful about cuts, bites and other skin injuries.

The outbreak is being treated as both an animal-health problem and a biosecurity issue. If screwworm continues moving north, it could increase costs and workload for ranches, veterinarians and state officials monitoring animals across Texas and neighboring states.

The broader background

New World screwworm was eradicated from the United States decades ago, but it has been moving north from Mexico and Central America since 2023. That movement has put Texas on the front line of renewed surveillance.

The June 4 case in South Texas marked the first Texas detection in years and set off the warning phase that is now widening to pets. What began as a livestock alert has become a broader reminder to check wounds early and take unusual lesions seriously, whether the animal is a calf, a goat, a dog or a cat.

For now, officials and veterinarians are still tracking the outbreak and refining the case count. The practical advice has stayed consistent: keep a close eye on outdoor animals, inspect wounds quickly and get veterinary care immediately if a lesion looks suspicious or gets worse fast.