[Sporotrichosis in a horse].

The study discusses the diagnosis and treatment of an Arabian horse suffering from sporotrichosis, a rarely seen fungal infection in Europe, at the University of Utrecht’s Department of Large Animal Surgery.

Case Presentation

• The study involved a 9-year old male Arabian horse which presented with multiple nodules on the inner part of the right hind leg. The configuration of the nodules suggested they followed a cutaneolymphatic pattern, meaning they were likely related to both the skin and lymphatic systems of the animal.

Diagnostic Process

• A sample from the nodules was examined under the microscope, revealing a granulomatous inflammation. This type of inflammation involves the formation of granulomas, which are collections of immune cells and are typically observed in chronic infections.
• Further analysis of the sample identified spheroid yeast-like organisms with budding throughout the tissue. These were detected in sections stained with Periodic Acid Schiff (PAS) and Grocott’s stain, two techniques used to highlight fungal organisms in tissue samples.
• The presence of these specific features suggested a preliminary diagnosis of sporotrichosis, a rare fungal infection caused by the Sporothrix schenckii organism.

Confirmation of Diagnosis and Treatment

• To confirm the diagnosis, another fresh sample from a nodule was cultured in a lab. The growth and identification of Sporothrix schenckii from this culture affirmed the sporotrichosis diagnosis.
• Following the confirmed diagnosis, antifungal therapy was initiated. The treatment successfully halted the development of new granulomas, indicating a positive response to the therapy.

Relevance of Findings

• The case is significant because sporotrichosis is a rare disease in Europe. However, it is commonly seen in the southern part of the U.S.A. This highlights the importance of including it in the differential diagnosis for horses presenting with skin and lymphatic system abnormalities, irrespective of their location.