Photodynamic therapy in the treatment of cutaneous habronemosis in a horse: Case report

Habronema muscae is a parasitic nematode that causes habronemiasis in horses, leading to chronic skin lesions. The parasite is transmitted via flies, and larvae deposited in wounds result in difficult-to-heal “summer sores”. This case study involved treating a 9-year-old gelding male horse with recurrent habronemiasis using photodynamic therapy (PDT) concurrent with conventional treatments. The horse presented with ulcerated, exudative wounds on its limbs and face, unresponsive to traditional treatments. PDT was applied over six months, using methylene blue (MB) as a photosensitizer, combined with LED irradiation. Additionally, an ivermectin-based ointment and other healing agents were used. The results showed a reduction in lesion size after two months, complete healing of the thoracic wounds by month four, and facial wound healing after six months. In this case, PDT was an effective adjunct treatment for managing habronemiasis.