Fly strike (myiasis) is a life-threatening emergency in rabbits that occurs when blowflies (most commonly Lucilia sericata — the green bottle fly) lay eggs on a rabbit’s skin, and the hatching larvae (maggots) feed on the rabbit’s flesh. Fly strike can progress from initial egg deposition to life-threatening tissue destruction within hours. The toxins released by feeding maggots cause rapid systemic shock, and death can occur within 24 hours if left untreated. Fly strike is most common in warm weather (spring through fall) and primarily affects rabbits that are unable to keep their hindquarters clean. Prevention is far more effective than treatment, and every rabbit owner should take active measures to protect their rabbit during fly season.
Overview
Blowflies are attracted to moisture, warmth, and the odor of feces and urine. They preferentially lay eggs on the perineal (bottom) region of rabbits that are soiled with feces or urine. Within 12 to 24 hours, the eggs hatch into larvae (maggots) that begin feeding on the rabbit’s skin and underlying tissue. The maggots release proteolytic enzymes and bacterial toxins that cause:
- Progressive tissue destruction (the maggots literally eat into the flesh)
- Severe pain and distress
- Systemic toxemia and shock
- Secondary bacterial infection and septicemia
- Rapid death if untreated
Risk factors for fly strike include:
- Dirty bottom (fecal or urine soiling) — The most important risk factor. Caused by obesity (rabbit cannot reach to eat cecotrophs), dental disease (painful eating leads to soft stools), arthritis (difficulty grooming), urinary incontinence, or diarrhea.
- Obesity — Overweight rabbits cannot reach their perineum to groom.
- Dental disease — Leads to abnormal cecotroph production and inability to eat them.
- Arthritis — Limits grooming ability, especially in older rabbits.
- Damp or dirty housing — Attracts flies and provides a breeding ground.
- Open wounds — Any wound can attract flies.
- Warm weather — Fly activity increases dramatically in warm months.
- Poor husbandry — Infrequent cage cleaning, inadequate bedding.
Symptoms
EMERGENCY — Seek immediate veterinary care if you notice any of the following:
- Visible maggots on or around the rabbit’s body (often around the bottom, tail area, or skin folds)
- Eggs visible as small white/yellow clusters on the fur
- Foul smell from the rabbit
- Lethargy, depression, loss of appetite
- Restlessness, discomfort, or teeth grinding
- Reluctance to move
- Wet, soiled perineal area
- Open wounds with tissue destruction
- Collapse or shock (cold ears, rapid breathing, unresponsive)
Check your rabbit’s bottom at least twice daily during warm weather. Early detection of eggs before they hatch can prevent fly strike.
Treatment
Fly strike is a veterinary emergency. Treatment involves:
Immediate Veterinary Care
- Remove all maggots — Under sedation or anesthesia, all visible maggots are carefully removed using forceps. The entire affected area must be thoroughly cleaned and debrided. This can be an extensive and painful process.
- Wound debridement — Dead and damaged tissue is removed to promote healing and eliminate further maggot food sources.
- Wound cleaning — Thorough lavage with sterile saline or dilute antiseptic solution.
- Pain management — Aggressive analgesic therapy:
| Medication | Purpose |
|---|---|
| Buprenorphine | Opioid for severe pain — fly strike is extremely painful |
| Meloxicam | NSAID for pain and inflammation |
- Fluid therapy — Aggressive subcutaneous or IV fluid support to treat dehydration and shock.
- Antibiotics — Systemic antibiotics (enrofloxacin or trimethoprim-sulfa) to treat secondary bacterial infection from maggot-contaminated wounds.
- Ivermectin — May be given to kill any remaining larvae in the tissue.
- Warmth — Keep the rabbit warm to combat shock.
- Nutritional support — Syringe feeding if the rabbit is not eating.
Post-Treatment Care
- Daily wound care and monitoring
- Continue pain management and antibiotics as directed
- Address the underlying cause of soiling (dental treatment, weight management, arthritis treatment)
- Keep the rabbit in a clean, fly-free indoor environment during recovery
Euthanasia Considerations
In severe cases where fly strike has caused extensive tissue destruction, deep wounds penetrating into the body cavity, or overwhelming systemic toxemia, humane euthanasia may be the most compassionate option. Your veterinarian will help you assess whether treatment is likely to result in a good quality of life outcome.
Prevention
Prevention is critical and involves multiple strategies:
- Check your rabbit’s bottom twice daily during warm weather — this is the single most important preventive measure
- Keep the perineal area clean and dry — Clean any soiling immediately
- Maintain a healthy weight — Obese rabbits cannot groom their bottoms
- Treat dental disease promptly — Dental issues lead to abnormal cecotrophs and soiling
- Treat arthritis — Pain-free mobility allows normal grooming
- Keep housing clean — Remove soiled bedding daily; clean the hutch or enclosure thoroughly at least weekly
- Use fly screens on outdoor enclosures
- Fly prevention products — Products such as Rearguard (cyromazine) can be applied to the rabbit’s fur to prevent maggot development for up to 10 weeks. Consult your veterinarian.
- Keep rabbits indoors during peak fly season when possible
- Ensure proper diet — A hay-based diet promotes normal, firm cecotrophs
Prognosis
- Fly strike caught very early (eggs or very few maggots, no significant tissue damage) — Good prognosis with prompt treatment.
- Moderate fly strike — Fair to guarded prognosis. Depends on the extent of tissue damage and systemic effects.
- Severe fly strike with extensive tissue necrosis or septicemia — Poor prognosis. Many severely affected rabbits do not survive even with aggressive treatment.
Frequently Asked Questions
Can indoor rabbits get fly strike? Yes, though it is much less common. Flies can enter homes through open windows and doors. Indoor rabbits with soiled bottoms are still at risk during warm weather.
How quickly does fly strike develop? Blowfly eggs can hatch within 12 to 24 hours of being laid, and maggots begin causing tissue damage immediately. The condition can progress from normal appearance to life-threatening within 24 hours. This is why twice-daily bottom checks are essential.
Is fly strike always fatal? No. Fly strike caught early, before significant tissue damage occurs, is treatable. However, advanced fly strike has a high mortality rate even with aggressive treatment.
What does Rearguard do? Rearguard is a liquid applied to the rabbit’s fur (mainly around the bottom area) that contains cyromazine, an insect growth regulator. It prevents blowfly eggs from developing into larvae for up to 10 weeks. It does not repel flies but stops maggot development. It should be used as part of a comprehensive prevention plan, not as the sole measure.
My rabbit has soft, sticky droppings around its bottom. What should I do? This is likely cecal dysbiosis (abnormal cecotrophs). Clean the area gently and consult your veterinarian to address the underlying cause (usually diet or dental disease). In the meantime, check the area frequently, as a soiled bottom dramatically increases fly strike risk.