Flystrike

Flystrike, also known as myiasis, is an infestation of living tissue by fly larvae (maggots), most commonly affecting sheep in temperate climates. Blowflies, particularly the common green bottle fly (Lucilia sericata), lay eggs on damp wool, torn skin, wounds, or areas contaminated with urine or feces. The eggs hatch within 24 to 48 hours in warm conditions, and the maggots feed on tissue, often causing rapid tissue destruction and secondary bacterial infection.

Two major forms occur. Breech strike is the most frequent, where maggots gather in the hindquarters, tail, or breech area, causing foul odor, swelling, and discomfort. Body strike involves maggots invading existing wounds or damaged skin elsewhere on the animal. Severe cases can lead to systemic illness, extreme weakness, and death if not treated promptly.

Diagnosis is typically clinical, based on visible maggots in fleece or wounds, foul smell, and signs of distress. Identification of the fly species can aid prevention but is not essential for treatment.

Treatment is an emergency veterinary matter. It involves removing maggots manually, clipping surrounding wool, cleaning and disinfecting the affected area, and applying appropriate topical or systemic antiparasitics. Wound care and antibiotics may be necessary to treat secondary infections, along with analgesia. In some cases, herd treatment and environmental control are advised to prevent recurrence.

Prevention focuses on good husbandry and fly control. Regular crutching or dagging, timely shearing, maintaining dry, clean fleece, promptly treating wounds, and removing or disposing of carcasses can reduce attack risk. Fly traps, repellents, and insect growth regulators may be used in high-risk periods. Prognosis improves with early intervention.