Habronemiasis in Donkeys: Summer Sores, Stomach Worms, and Fly Control

Quick Answer
  • Habronemiasis is a parasite problem in equids caused by Habronema or Draschia stomach worms, and in donkeys it often shows up as warm-weather skin lesions called summer sores.
  • Flies spread the larvae. When larvae are deposited on wounds, eyes, lips, nostrils, or genital tissue instead of being swallowed, they trigger itchy, nonhealing, proud-flesh-like sores.
  • Common clues include ulcerated sores that drain, intense irritation, yellow gritty material in the wound, and lesions that flare in spring and summer or recur each year.
  • Your vet may diagnose it from the lesion appearance, skin scrapings or biopsy, and sometimes fecal testing or gastroscopy when stomach-worm infection is a concern.
  • Treatment usually combines deworming, wound care, anti-inflammatory therapy, and strict fly control. Early care often shortens healing time and lowers recurrence risk.
Estimated cost: $200–$1,900

What Is Habronemiasis in Donkeys?

Habronemiasis is a parasitic disease of equids, including donkeys, caused by Habronema species and sometimes Draschia megastoma. Adult worms live in the stomach and may cause little obvious trouble there, but the larvae can create a very different problem when flies deposit them on skin or moist tissues. That skin form is called cutaneous habronemiasis, or summer sores.

In donkeys, summer sores often develop around the lips, corners of the eyes, nostrils, sheath or genital area, lower belly, and any wound that attracts flies. Instead of completing their normal life cycle, the larvae get trapped in the tissue and trigger a strong inflammatory reaction. The result can look dramatic: a raw, itchy, proud-flesh-like lesion that does not heal normally.

These sores are usually most active in spring, summer, and early fall when fly pressure is high. Some donkeys improve during colder months, then flare again the next warm season. Because other conditions can look similar, including infected wounds and some tumors, your vet is the right person to confirm what is going on.

Symptoms of Habronemiasis in Donkeys

  • Nonhealing skin wound or ulcer, especially in warm months
  • Raised, fleshy, proud-flesh-like lesion
  • Intense itching or rubbing at the site
  • Yellow-white gritty material or small 'rice-grain' concretions in the sore
  • Blood-tinged or greasy discharge from the lesion
  • Lesions at the lips, eye corners, nostrils, genital area, lower abdomen, or existing wounds
  • Swelling and irritation around the eyes or mouth
  • Recurring sores in the same area each summer
  • Less commonly, vague stomach-worm concerns such as poor coat or mild digestive irritation, though gastric infection often causes few obvious signs

When to worry: call your vet promptly if a sore is getting larger, bleeding, attracting heavy fly activity, or forming thick proud flesh. Eye-area lesions, genital lesions, and any wound that is painful or rapidly worsening deserve faster attention because they can be hard to manage and may mimic other serious conditions.

See your vet immediately if your donkey has a lesion near the eye, trouble eating, marked swelling, severe pain, or a wound that suddenly looks infected. Summer sores can become chronic, and early treatment is often easier than trying to control a large, long-standing lesion later.

What Causes Habronemiasis in Donkeys?

Habronemiasis starts with the life cycle of equine stomach worms. Adult worms live in the stomach and pass eggs or larvae into manure. Fly maggots develop in that manure, pick up the parasite, and later mature into adult flies carrying infective larvae.

Normally, those larvae are deposited around the mouth and then swallowed, returning to the stomach. But when flies feed on wounds or moist tissues like the eyes, lips, nostrils, or genital area, the larvae are misplaced. In the skin, they cannot mature properly, so they trigger a strong local inflammatory reaction instead.

That is why warm weather, heavy fly exposure, poor manure management, wet feed, soiled bedding, and untreated skin injuries all raise risk. Donkeys with recurring summer sores may also seem especially sensitive, although recurrence does not mean anyone did something wrong. It usually means the parasite life cycle and fly exposure were able to restart.

How Is Habronemiasis in Donkeys Diagnosed?

Your vet usually starts with the history and appearance of the lesion. A sore that appears in fly season, does not heal, itches, and contains yellow gritty material is strongly suspicious for summer sores. Location matters too. Lesions near the eyes, lips, genital tissue, and old wounds are classic.

Because several problems can look similar, your vet may recommend skin scrapings, cytology, or biopsy. Biopsy can help confirm calcified concretions and inflammation linked to habronemiasis, and it is especially important when the lesion is large, unusual, or in an area where tumors such as sarcoid or squamous cell carcinoma must be ruled out.

If stomach-worm infection is also a concern, your vet may discuss fecal testing or, less commonly, gastroscopy. Habronema eggs can be hard to detect on routine fecal exams, so a negative test does not fully rule the parasite out. That is one reason diagnosis often depends on the whole picture rather than one test alone.

Treatment Options for Habronemiasis in Donkeys

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$200–$450
Best for: Mild to moderate suspected summer sores in a stable donkey that is still eating, comfortable, and able to be managed at home
  • Physical exam by your vet
  • Targeted deworming plan chosen by your vet, often using a macrocyclic lactone when appropriate
  • Basic wound cleaning and clipping of surrounding hair
  • Topical wound protection or bandaging when feasible
  • Focused fly control: manure removal, fly spray or repellent, fly mask, and wound protection
  • Short recheck if the lesion is improving
Expected outcome: Often fair to good when the lesion is caught early and fly exposure is reduced quickly.
Consider: Lower upfront cost range, but healing may be slower if the lesion is large, in a difficult location, or already has heavy proud flesh. Some donkeys still need biopsy, stronger anti-inflammatory care, or repeat visits.
Most Common

Recommended Standard Treatment

$450–$900
Best for: Most donkeys with active summer sores, especially lesions that are painful, recurrent, draining, or forming exuberant granulation tissue
  • Exam and lesion assessment by your vet
  • Deworming protocol selected by your vet
  • Sedation if needed for safe wound handling
  • Debridement or more thorough cleaning of the lesion
  • Cytology, skin scraping, or biopsy when diagnosis needs confirmation
  • Anti-inflammatory treatment plan from your vet, which may include corticosteroid therapy when appropriate
  • Topical medications and bandaging plan
  • Structured fly-control program for the donkey and environment
  • Follow-up visit to monitor healing
Expected outcome: Good in many cases, though recurrence is possible in future fly seasons.
Consider: Higher cost range and more hands-on care, but this approach usually gives a clearer diagnosis and better control of inflammation, wound healing, and recurrence risk.

Advanced / Critical Care

$900–$1,900
Best for: Large, chronic, recurrent, eye-adjacent, genital, or nonresponsive lesions, or cases where your vet needs to rule out cancer or another serious condition
  • Everything in standard care, plus more extensive diagnostics or procedures
  • Deep biopsy to rule out underlying tumor or another disease process
  • Gastroscopy or expanded parasite workup if stomach involvement is being investigated
  • Surgical debulking or cautery of excessive granulation tissue when needed
  • Management of difficult eye, genital, or extensive limb lesions
  • Repeated bandage changes, sedation, or referral-level wound care
  • Culture or additional testing if secondary infection or another diagnosis is suspected
Expected outcome: Variable but often improved when advanced care addresses both the lesion and the underlying look-alike conditions.
Consider: Most intensive cost range and more visits, but it can be the most practical option for complex lesions that are not healing or are in high-risk locations.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Habronemiasis in Donkeys

Bring these questions to your vet appointment to get the most out of your visit.

  1. Does this lesion look most consistent with summer sores, or are there other conditions you want to rule out?
  2. Do you recommend a biopsy or skin scraping for this sore, especially based on its location and appearance?
  3. What deworming option makes sense for this donkey, and do you want to treat herd mates too?
  4. Is there proud flesh or secondary infection that needs separate treatment?
  5. What kind of wound covering, topical care, or bandaging is realistic for this body area?
  6. Which fly-control steps will make the biggest difference on our property right now?
  7. How soon should we expect improvement, and what signs mean the plan is not working?
  8. If this comes back next summer, what prevention plan should we start before fly season peaks?

How to Prevent Habronemiasis in Donkeys

Prevention focuses on breaking the parasite-fly cycle and protecting your donkey from fly-fed wounds. The most helpful steps are regular manure removal, disposal of wet feed and soiled bedding, prompt cleaning of cuts and abrasions, and a practical fly-control plan. Fly masks, physical barriers, repellents labeled for equids, and reducing standing organic waste can all help lower exposure.

Work with your vet on a targeted deworming program rather than guessing. Current equine parasite guidance supports using macrocyclic lactones strategically where indicated for spirurid stomach worms, while avoiding unnecessary deworming. That matters because no single schedule fits every farm, climate, or donkey group.

If your donkey has had summer sores before, start prevention before peak fly season. Check common problem areas often, especially the eyes, lips, lower belly, sheath, and any healing wounds. Early attention to tiny lesions can make a big difference. Even with good management, some donkeys may have seasonal recurrence, so the goal is risk reduction and faster response, not perfection.

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