What Texas Pet Owners Need to Know About New World Screwworm

“Check your pets regularly for wounds,” Texas veterinarians say.

Pet owners should be vigilant, but not panicked, about New World Screwworm (NWS), Texas veterinarians say. 

“NWS is moving rapidly north through Mexico and will likely appear on our side of the border soon,” said Dr. Nancy Carter, president of the Texas Veterinary Medical Association. “This pest is primarily a threat to livestock, but it can also infect pets, wildlife and even humans.” 

NWS flies lay eggs in wounds or skin openings of mammals and birds. The flies can infest even small breaks in the skin, like scratches, insect bites or surgical incisions. NWS can cause severe tissue damage, infections and even death if left untreated. Along with state, national and international authorities, large animal veterinarians and livestock owners have been anxiously tracking the flies from their former quarantine zone in Panama. Most recently, an infected cow was found less than 70 miles from the Rio Grande. 

Here's what Texas pet owners should watch for, Dr. Carter says: 

• Unusual swelling or discharge from any skin wound, no matter how small 
• Foul odors. Infested wounds have a very distinctive, strong smell. 
• Behavioral changes such as pain, licking or chewing at a wound, loss of appetite or lethargy 

“If you suspect your pet might have NWS, seek veterinary care immediately,” Dr. Carter said. “Do not try to treat the infection. There are no safe home remedies.” 

Veterinarians will examine your pet and send any specimens off to the Texas Animal Health Commission for testing. Veterinarians are staying alert for any suspicious wounds on their patients and training their clinical staff to recognize NWS. 

“We’ve eradicated NWS before,” Dr. Carter said. “There’s no need to panic.” 

The last U.S. outbreak of NWS, in 2016, was controlled quickly thanks to a Florida veterinarian who identified a case in a stray dog. In the 1960s, millions of sterilized male flies were released over infected herds in Texas and other states. This worked because sterilized male flies stop NWS flies from reproducing. The U.S. Department of Agriculture is constructing large new sterile fly production facilities in South Texas and in Mexico. The Texas Department of Agriculture is deploying other new technologies, and the U.S. already has closed its ports to cattle, bison and horse imports from Mexico.

“Remember,” Dr. Carter said, “check your pets regularly for wounds, keep them clean, and call your veterinarian right away if you see anything unusual.” 

For more information contact Trent Hightower, JD, Director of Government Relations/General Counsel, 512-452-4224.