Not Just Livestock: Dangerous Screwworm Parasite Infects A Dog in Texas

There is a lot of talk about the New World Screwworm and how it could devastate the Texas cattle industry. Cows are not the only animals at risk. Pet owners in Central Texas need to be on high alert.

Texas Scrambles to Contain New World Screwworm Surge

According to an announcement from the U.S. Department of Agriculture, the state's total case count has now reached four. The newly identified infections involve a calf located in La Salle County and a domestic dog in Andrews County. According to Fox44 News, he infected dog had recently traveled across the border from Mexico.

Deploying the "Sterile Fly" Defense

The battle against the invasive parasite relies on a specialized biological strategy. Governor Abbott recently modified a statewide emergency declaration aimed specifically at accelerating the production of sterile screwworm flies. This technique introduces millions of infertile insects into the wild to disrupt the pest's reproductive cycle.

Beyond Livestock: The Threat of the New World Screwworm to Pets and Humans

The scary thing about the New World screwworm (NWS) is that it affects more than livestock. Veterinarians are warning that this flesh-eating parasite also poses a danger to other warm-blooded species, including household pets and humans.

Why the Screwworm is Especially Dangerous

Olufemi A. Akinkuotu, DVM, MVSc, PhD, and Assistant Professor of Veterinary Parasitology at Texas Tech University School of Veterinary Medicine, is a leading authority on the pest. He says the parasite is uniquely dangerous because it does not require an existing injury to cause harm. Unlike typical blowflies associated with standard larval infestations, the NWS fly can initiate wounds directly in completely healthy, intact tissue. Once a single infestation takes root, it can cause devastating, deep-tissue destruction within just a few days.

Fast Moving Threat

At the time Dr. Akinkuotu was interviewed in June of 2025, the flies had not yet reached the United States. At that point, active cases were documented 700 miles south of the U.S.-Mexico border. Now that the fly has appeared in the southern United States, it appears containment methods, such as the release of sterile male insects throughout Central America and Mexico, have failed to stop the parasite's northward migration.

Behavioral Patterns and Clinical Signs

While the adult female fly is attracted to the odor of open injuries, she is also capable of depositing her eggs directly onto exposed mucous membranes or natural body cavities. This includes an animal's nasal passages, mouth, eyes, and genitalia. Once the eggs hatch, the larvae immediately burrow inward, creating painful lesions that quickly attract additional flies to the site.

What to Look For

When evaluating mammals and birds, veterinarians and owners should look for:

Behavioral Changes: Marked irritability, distress, or persistent head shaking.

Physical Evidence: A distinct odor of tissue decay, or visible maggots clustered inside mucous membranes or deep within wounds.

Insect Identification: The presence of adult flies, which are slightly larger than typical houseflies and possess a metallic blue or green coloration, vibrant orange eyes, and three prominent dark stripes running down their backs.

Domestic Pets

In domestic pets, screwworm infestation is frequently misdiagnosed because it closely mimics other common medical issues, such as deep bacterial abscesses, or necrotizing skin infections. Pet owners need to take action if a minor scratch rapidly degenerates into a foul-smelling injury with visible larvae buried deep beneath the skin's surface.

How to Report Suspected Infections

Time is critical to preventing a widespread outbreak. If you detect a suspicious wound or suspect a parasitic infection, contact state authorities immediately:

For Domestic Pets and Livestock: Contact the Texas Animal Health Commission at 1-800-550-8242.

For Wild Deer and Other Wildlife: Contact the Texas Parks and Wildlife Department at 512-389-4505.

Directions for Pet Owners

Domestic pet owners residing in high-risk zones should proactively minimize environmental hazards. Animals that spend significant time outdoors, such as hunting dogs, working herding breeds, or those living near livestock operations, require daily physical inspections.