Every horse owner knows the feeling. You turn your horse out looking perfectly fine, only to find a new scrape, rub, or mystery wound by the end of the day. Most are minor inconveniences, but they serve as a reminder of the importance of daily observation and prompt wound care.
With increased awareness surrounding New World screwworm, now is a good time to revisit the everyday management practices that help protect horses, dogs, and livestock throughout fly season. While there are currently no confirmed cases in U.S. horses, prevention starts with staying informed, managing wounds promptly, and maintaining effective fly control before small problems have a chance to become bigger ones.
What Is New World Screwworm?
New World screwworm is a parasitic fly whose larvae (maggots) feed on living tissue in warm-blooded animals.
Female flies are attracted to wounds and body openings, where they lay eggs. The eggs hatch into larvae that burrow into the affected area and feed on living tissue as they develop. Unlike common maggots, which typically feed on dead or decaying tissue, New World Screwworm larvae require living tissue to survive.
Because even small wounds can attract flies, horse owners should pay attention to cuts, scrapes, surgical incisions, insect bites, and other breaks in the skin.
Animals affected by New World screwworm may develop wounds that become larger over time rather than healing normally. Infested wounds are often painful and may have a foul odor.
Horse owners should watch for:
- Cuts, scrapes, or wounds that aren’t healing normally.
- Excessive drainage or discharge.
- A foul odor coming from a wound.
- Swelling or irritation around an injury.
- Visible larvae in a wound.
- Changes in behavior that suggest pain or discomfort.
If you notice any of these signs, contact your veterinarian immediately.
Make Daily Checks Part of Your Routine
Most horse owners already do a quick once-over during feeding time. But it’s easy to miss small wounds hiding beneath a thick mane, under a fly sheet, or in places we don’t routinely inspect.
Taking a few extra moments to look your horse over from nose to tail can help you spot cuts, abrasions, skin irritation, or areas that aren’t healing normally.
Pay particular attention to areas where injuries can go unnoticed, including:
- Under the jaw and throatlatch
- Around the sheath or udder
- Between the hind legs
- Around the coronary bands and heels
- Beneath blankets, boots, and tack
Catching a wound early often means it’s easier to manage and less likely to develop complications.
Don’t Let Small Wounds Become Big Problems
Any break in the skin deserves a little attention, especially right now. Clean wounds promptly, monitor them regularly, and contact your veterinarian if you notice excessive swelling, drainage, heat, odor, or delayed healing. What starts as a minor injury can become more difficult to manage if it goes unnoticed.
This is particularly important during fly season, when insects are naturally attracted to damaged skin. Flies can irritate wounds, delay healing, and increase the risk of complications if they’re allowed to congregate around an injury. After cleaning the affected area, consider using a fly-repellent product designed for wounds and sensitive skin to help keep flies away from abrasions, cuts, and other vulnerable areas.
For larger wounds or situations where insect pressure is especially high, products such as Screw Worm Aerosol Multi-Purpose Insecticide Spray can provide additional protection. The permethrin-based spray is labeled to help control flies, maggots, and other insects that may be attracted to wounds while supporting a cleaner healing environment.
Fly control doesn’t stop with wound care products. Physical barriers such as fly masks, fly sheets, and fly boots can help reduce insect pressure, especially during the peak of summer. Fly masks protect sensitive areas around the eyes, ears, and face, while fly sheets and boots help shield the body and legs from biting insects. And if you find the bugs really bad, try rotating fly sprays throughout the week and applying them to your horse before and after putting fly gear on. Although they won’t eliminate every fly, these tools can reduce irritation, discourage rubbing, and help limit opportunities for flies to target vulnerable skin.
Related: Help, My Horse Has a Wound!
Fly Control Is About More Than Comfort
Nobody enjoys a horse that spends all day stomping flies, but fly control isn’t just about keeping horses comfortable. Good fly management is an important part of overall herd health.
Simple practices such as removing manure regularly, reducing standing water, cleaning stalls, and using fly-control products appropriately can help reduce fly populations around the barn.
For many horse owners, these are already part of their summer routine. Consistency is often more important than adding new products or completely changing your management program.
Remember the Other Animals on the Property
Many horse properties are home to more than just horses.
Barn dogs, cattle, goats, sheep, and other livestock can all benefit from the same attention to wound care and fly control. A quick visual check while feeding or doing chores can help identify cuts, skin irritation, or healing issues before they become larger concerns.
Good management practices rarely benefit only one species.
Related: Tips for Minimizing Flies on Your Horses and Property
Work With Your Veterinarian
Veterinary organizations continue to evaluate prevention and treatment options for New World screwworm should they become necessary in the United States. Because recommendations and approved products may evolve, your veterinarian remains the best resource for questions specific to your animals and location.
At the time of publication, there have been no confirmed cases of New World screwworm in horses in the United States. The USDA Animal and Plant Health Inspection Service continues to monitor detections through ongoing surveillance efforts and maintains a public dashboard tracking confirmed animal cases and wild fly detections. While active cases have been identified in other livestock species, the absence of confirmed equine cases is exactly why prevention remains so important.
Rather than stocking up on products or making major management changes, focus on practical prevention measures: promptly treating wounds, maintaining effective fly control, and staying vigilant for any signs of infection or delayed healing. Just as importantly, maintain a strong relationship with your veterinarian and stay informed through reputable sources such as the American Association of Equine Practitioners, USDA APHIS, and your state animal health officials. An informed horse owner is the first line of defense against emerging animal health threats.
This article originally ran on HorseandRider.com.
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