Chromomycosis in a horse.

The research details the diagnosis and treatment of chromomycosis, a rare skin disease, in a 6-year-old Quarter Horse. The condition was identified due to a spherical lesion on the horse’s skin, with microscopic examination confirming the presence of fungal elements.

Study Background

• This article discusses a case of a 6-year-old Quarter Horse gelding that was investigated because of a dermal nodule at the right tuber ischii.
• The nodule was firm, brown-black, and clearly defined. It was roughly spherical in shape.

Diagnosis and Excision

• The nodule was excised and did not reappear afterwards, leading to the conclusion that the cause of the nodule was completely removed.
• A microscopic analysis was carried out on the dermis of the taken specimen. Multiple pyogranulomas were observed in the dermis.
• Many of the pyogranulomas contained thick-walled, dark brown fungal elements. Some had an internal division (septation) that is associated with chromomycotic fungi.

Conclusion

• The horse was therefore diagnosed with chromomycosis, a skin condition that is rarely seen in such animals.
• The authors suggest that chromomycosis should be considered as a possible diagnosis for horses presenting with nodular and/or pigmented skin lesions.
• Other possible causes of such lesions include melanoma, pyogranuloma, mycetoma, squamous cell carcinoma, habronemiasis, and onchocerciasis.