Equine cutaneous fungal granuloma: a study of 44 lesions from 34 horses.

The research discusses a study over a 14.5-year period, on 44 cutaneous fungal granulomas identified in 34 horses. The study concludes that equine cutaneous fungal granulomas, a noninvasive nodular skin condition, are relatively common among horses in the Pacific Northwest. Cure was achieved through surgical removal of the granulomas.

Study Sample and Timescale

• The research was conducted on a sample of 34 horses, with 44 identified lesions over a span of 14.5-years.
• The age of the horses had a mean value of 6.1 years, with a range from 1 to 19 years. This suggests that younger horses were most commonly affected.
• No explicit bias towards a specific horse breed or sex was observed throughout the study.

Characteristics of the Granulomas

• The granulomas, which were identified to be either single or multiple, were mainly found on the head and neck regions of the horses.
• Their histology revealed them to be nodular masses in the dermis with a mean diameter of 7.3 mm, having an intact overlying epithelium.
• Most often, these lesions exhibited severe lymphocytic inflammation, along with pyogranulomatous inflammation that was associated with moderate amounts of fungal elements.

Causative Fungi and Granuloma Incidence

• The causative agents for these granulomas were both pigmented and nonpigmented fungi of varying morphology.
• In three cases, penetrating plant material was identified within the granulomas.
• It was observed that granulomas caused by nonpigmented fungi were more common in horses located in wet regions, whereas horses in dry regions exhibited granulomas caused by both pigmented and nonpigmented fungi.
• The occurrence of these granulomas was found more common from February to November, peaking in April and July.
• No correlation was found between the yearly incidence of the granulomas and the average temperature or rainfall per year.

Conclusion and Treatment

• After studying the characteristics, causative agents, and occurrence pattern of these granulomas, it was observed that equine cutaneous fungal granuloma occurs quite frequently among horses in the Pacific Northwest region.
• Although the morphology of the causative fungi varied, the signalment, historical, clinical and overall histological features amongst the entire sample were quite similar.
• Surgery proved to be an effective curative treatment for these granulomas.