Sporotrichosis is caused by the fungal agent, Sporotrichium (Sporothrix) schenckii. The disease in horses is initiated through contamination of a skin wound. The fungus is a soil saprophyte. Nodules will develop at the site of entry and then the fungus spreads through lymphatics. This causes thickening or cording of the lymphatics with nodules appearing along the chain. The nodules are between 1 and 5 cm in diameter, and will typically begin large and some will ulcerate, leaching a cream-coloured fluid, that is described as honey-like.
Treatment in early cases are local and systemic iodides. For more advanced cases systemic anti-fungal therapy is indicated, such as itraconazole (5 mg/kg PO sid). The course of treatment may be several months (up to 6 months).
Sporotrichium schenckii is a zoonotic concern. Commonly referred to as ‘rose handler’s disease’ and seen in florists, farmers, and gardeners. Transmission of sporotrichosis has occurred between infected horses and vets.
Tags: Dermatology; Zoonoses