06/08/2026
🚨 NEW WORLD SCREWWORM (NWS): WHAT PET & LIVESTOCK OWNERS NEED TO KNOW
Recent cases of New World Screwworm (NWS) have increased concerns across Texas and the southern United States. New World Screwworm is caused by the larvae (maggots) of the screwworm fly. Unlike typical maggots that feed on dead tissue, screwworm larvae invade and feed on living tissue, causing painful wounds, severe infections, tissue destruction, and potentially death if left untreated.
What should you watch for?
• Open wounds that fail to heal
• Bloody or foul-smelling discharge
• Excessive licking, chewing, or irritation around a wound
• Visible maggots within a wound
• Depression, decreased appetite, or weight loss
Daily Surveillance & Monitoring is key to early intervention!
Producers should routinely inspect:
• Surgical sites (castrations, dehorning, branding)
• Ear tag sites
• Navel areas of newborn calves, lambs, and kids
• Sheath, v***a, and other natural body openings
• Tick bites and wounds from fences, predators, or fighting
• Any draining, enlarging, or foul-smelling wounds
Prompt Wound Management, treatment of navels at birth, and treatment of wounds daily is necessary to aid in the prevention of an infection. The female screwworm fly is attracted to open wounds and lays eggs along the wound edges. Proper wound care is one of the most important prevention measures.
Recommendations:
• Treat wounds immediately
• Monitor healing closely
• Utilize fly control measures
• Avoid unnecessary procedures during periods of high fly activity when possible
• Check newborn animals frequently during the first weeks of life
Prevention & Treatment Options Available at GVVC:
We offer several products that may help reduce risk and support treatment protocols when appropriate, give us a call if you have any concerns or questions:
🐄 Dectomax® (Doramectin) — FDA conditionally approved for prevention and treatment of New World Screwworm infestations in cattle and prevention of reinfestation for up to 21 days.
🩹 Permethrin Spray — Can be used as part of a fly-control program to reduce fly pressure around animals and wounds.
🐶 Credelio Quattro® – Helps provide broad-spectrum parasite protection and has been authorized for treatment of New World Screwworm infestations in dogs.
🐶 Credelio® – Monthly flea and tick protection and authorized for treatment of New World Screwworm infestations in dogs.
🐱 Credelio CAT® – Monthly flea and tick protection and authorized for treatment of New World Screwworm infestations in cats.
If you notice a wound containing maggots or suspect a screwworm infestation:
• Contact your veterinarian immediately.
• Take photos if possible.
• Do not move affected livestock until veterinary guidance is obtained.
• Early diagnosis and treatment greatly improve outcomes.
We are closely monitoring the New World Screwworm situation and are committed to helping protect the health of your pets and livestock. We are working closely with the Texas Animal Health Commission and other animal health officials as this situation continues to evolve. We will keep our clients and community informed with the latest recommendations, updates, and prevention strategies as new information becomes available.
If you have concerns about a wound or would like to discuss prevention options, give us a call. Early intervention is crucial.
Office: (830) 672- 8676
