WHAT IS SCREWWORM: How to Prepare
- Winding Branch Ranch
- Jun 11
- 3 min read
Screwworm is a serious animal health threat that every livestock owner, pet owner and animal caretaker should understand.
New World screwworm is caused by the larvae of a fly. These larvae can enter open wounds and feed on living tissue, making even small cuts, scrapes or irritated areas dangerous if they are not treated quickly.
Screwworm can affect cattle, sheep, goats, horses, donkeys, pigs, dogs, cats, wildlife and birds. The biggest risk is any animal with an open wound, recent birth, skin irritation, surgical site or injury.
Why Animal Owners Should Pay Attention
Screwworm can spread quickly and cause serious damage if it is not caught early. A small wound can become larger, deeper, painful and infected.
Animal owners should be especially careful during warm weather, when flies are active and animals are more likely to have bites, scratches or irritated skin.
This is also why summer preparation matters so much for sanctuaries, farms and animal caretakers. Clean water, healthy pastures, dry bedding, good fly control and safe housing all play a role in keeping animals healthier during the hardest months of the year.
Signs of Screwworm in Animals
Check your animals daily and watch for:
Wounds that are getting worse instead of healing
A foul smell from a wound
Maggots or movement in a wound
Swelling, bleeding or drainage
Animals licking, biting or scratching one area
Head shaking
Loss of appetite
Weakness or unusual behavior
Any wound with maggots should be treated as urgent.
Where to Check Your Animals
Pay close attention to:
Ears
Eyes
Nose
Mouth
Tail area
Genitals
Hooves and legs
Tick bites
Cuts, scrapes and puncture wounds
Umbilical cords on newborn animals
Long-haired animals, wool sheep and animals with thick coats may need a closer hands-on check.
How to Prepare for Screwworm
The best protection is early detection, wound care and fly prevention.
Animal owners should:
Check animals every day
Clean and treat wounds quickly
Call a veterinarian if a wound looks unusual
Keep bedding, stalls and pens clean and dry
Remove manure and wet bedding often
Use fly control products approved for your animals
Watch newborn animals closely
Avoid unnecessary animal movement if screwworm is nearby
Quarantine new animals before introducing them to the herd or flock
Keep basic wound-care supplies ready
Do not use medications, insecticides or livestock treatments without reading the label and checking with your veterinarian.
At Winding Branch Ranch, summer readiness is about more than comfort. It helps us keep the animals who call the sanctuary home safer, cleaner and healthier through heat, flies, pasture stress and increased wound risk.
What to Do If You Suspect Screwworm
If you see maggots in a wound or suspect screwworm, contact your veterinarian right away.
Keep the animal contained and separated if possible. Do not move the animal off the property unless your veterinarian or animal health officials tell you to. Fast reporting helps protect your animal and helps prevent spread.
How You Can Help
Our Summer Ready campaign supports the behind-the-scenes work that keeps sanctuary animals safer during the hottest and most demanding months of the year.
This includes clean water systems, pasture and irrigation needs, fencing repairs and animal care supplies that help us respond quickly when animals need extra attention.
If you are able, a gift to Summer Ready helps us continue preparing responsibly for the season ahead.
The Bottom Line
Screwworm is serious, but preparation helps. Check your animals daily, treat wounds quickly, reduce flies and call your veterinarian if anything looks wrong.
A few minutes of prevention can make a major difference for the animals in your care.
Sources:
USDA APHIS: New World Screwworm Prevention for Animals
USDA APHIS: USDA Confirms Presence of New World Screwworm in the United States
Texas Animal Health Commission: New World Screwworms
Texas A&M AgriLife Extension: New World Screwworm
FDA: Animal Drugs for New World Screwworm
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