Guide to Summer Sores

What Are Summer Sores?

Summer sores are skin lesions caused by the larvae of certain stomach worms, particularly Habronema and Draschia species. These larvae are deposited onto open wounds or moist areas (like eyes or genitals) by flies—primarily stable flies and houseflies. Instead of being ingested and completing their lifecycle in the stomach, the larvae burrow into the skin, causing intense irritation and granulomatous inflammation.

Symptoms of Summer Sores

• Non-healing skin lesions, typically on legs, chest, sheath, or face

• Yellowish, gritty discharge (may contain calcified larvae)

• Intense itching and inflammation

• Proud flesh or excessive granulation tissue

• Possible secondary infections

• Lesions that worsen in warm, fly-heavy months

Diagnosis

Veterinarians typically diagnose summer sores based on:

• Clinical signs and lesion appearance

• Seasonality and exposure to flies

• Biopsy or skin scraping (to confirm the presence of larvae or to rule out other causes like squamous cell carcinoma or sarcoids)

Treatment Protocol

1. Veterinary Medical Treatment

• Antiparasitic drugs: Ivermectin or moxidectin administered orally to eliminate stomach worms and migrating larvae. Some studies recommend weekly Ivermectin for 4 weeks or until lesion is inactive and healing - Ask your veterinarian before trying this.

• Corticosteroids: Reduce inflammation and immune reaction (often topical or injectable).

• Antibiotics: If a secondary infection is present.

• Topical treatments: Medications containing corticosteroids and antimicrobials (e.g., dexamethasone/triple antibiotic ointments).

• Surgical debridement: In some cases, removal of excessive granulation tissue may be necessary.

2. Wound Care at Home

• Clean the lesion daily either by wiping with clean towel or gauze, if contaminated with dirt using a mild antiseptic like diluted chlorhexidine or betadine, or plain clean water. Remove any fly larva (white-yellow specks of rice-like areas) as this continues the inflammation cycle and irritation. This encourages the horse to chew and rub, increasing bleeding, attracting flies and inhibits healing.

• Apply prescribed topical treatments as directed by veterinarian. We use our veterinary prescription cream containing steroid/antibiotic/antifungal in a zinc base on active lesions. We use the No Pressure Heal Shield Pads to keep creams on the wounds.

  • Once they are inactive and start healing we try balance wet and dry - keep dry, but not so the skin cracks (we use butt paste), not too wet so tissue breaks down (use cornstarch baby powder or coat defense powder). Its a daily balancing act!!

  • The final step is o prevent reoccurrence. At the very first sign of a fly n that area we spray with Aluminum Spray as a barrier

• Keep the area dry and covered if possible (fly boots, wraps, or masks). This is where Heal Shield can help - 😊

  • For standing bandages check out our friends at Strappy Wrap for the most amazing compression bandages - super easy to use https://strappywrap.com

• Do not use irritating home remedies (like bleach or strong iodine).

Fly Control Is Crucial

Preventing fly contact is essential for both treatment and prevention: Fly spray, fly balm, fly powers. Our favorite is Bug-Off by Pure Sole check out their website https://www.puresolehoof.com (Use our code puresole10)

Environmental Management

• Remove manure daily

• Use fly predators in manure piles

• Keep feed areas clean and dry

Protective Measures

• Use fly sprays and fly masks/boots/sheets

• Stable horses during peak fly hours (early morning and evening)

• Install fans in barns to reduce fly activity

Prevention of Future Summer Sores

• Implement a consistent deworming program with veterinary guidance

• Address wounds promptly and protect them from flies

• Consider routine fecal exams to monitor parasite loads

• Reduce fly population around the property with integrated pest management

When to Call the Vet

Contact your veterinarian if:

• A wound is not healing within a week

• The horse is excessively itching or uncomfortable

• The lesion is rapidly growing or bleeding

• You suspect a summer sore due to the time of year and fly activity

Conclusion
Summer sores are a frustrating yet preventable condition. Early treatment, aggressive fly control, and good wound hygiene are key to minimizing discomfort and ensuring a swift recovery. Partner with your veterinarian for tailored care and prevention strategies.