Habronemiasis (Equine Summer Sore) in an 8-year-old Arab Horse

Abstract

Introduction: Habronemiasis, equine summer sore, is caused by habronema larvae, commonly in tropical and subtropical climates. House flies, face flies, and stable flies transmit the pathogenic nematode larvae. Cutaneous habronemiais is the most common form of habronemiasis in horses. Cutaneous habronemiais is associated with the deposition of larvae in areas where they cannot complete their life cycle. Deposition of larvae is related to local hypersensitivity. Habronema larvae could cause preocular infectious resulting in conjunctivitis, blepharitis, or dermatitis.  

Case report: An eight-year-old male Arabian horse was referred to the Large Animal Medicine Unit, Veterinary Clinical hospital, Shiraz University, Shiraz, Iran, with a history of wounds on the preocular region and hind limbs. The right eye's ocular examination revealed abundant mucopurulent discharge, blepharospasm, and chemosis. The granulomatous tumor had a diameter of 1.8 cm and was evident on the palpebral conjunctiva of the medial canthus. The skin lesion was identified as habronemiasis based on the history, clinical symptoms. Treatment includes prednisolone tab with reducing dosage for 30 days, an oral dose of Ivermectin, topical oxytetracycline ointment for seven days, chloramphenicol and triamcinolone eye drop for seven days. The diagnosis was confirmed due to the positive reaction of the lesions to treatment protocol.

Conclusion: Ocular habronemiasis is the common form of habronemiasis. Deposing of dead larva causes a hypersensitivity reaction. Treatments include corticosteroid to reduce inflammation-association tissue proliferation, antibiotic ointment for prevention of second bacterial infection, an antihistamine for the prevention of histamine-mediated pruritic and allergic conditions, and oral antihelminth for the killing of adult form in the stomach. The current study authors suggest fly control is essential in preventing habronemiasis.