Phaeohyphomycosis due to Pyrenophora phaeocomes and Drechslera nobleae in an Appaloosa mare.

The study details the successful diagnosis and treatment of a skin infection called phaeohyphomycosis in a 21-year-old Appaloosa mare. The infection, caused by the pigmented fungi Pyrenophora phaeocomes and Drechslera nobleae, was identified through histopathology, PCR, and 18S rRNA gene sequencing, and effectively treated through surgical excision.

Identification and Diagnosis

• The 21-year-old Appaloosa mare, a horse breed, was presented with a pigmented skin mass at the base of the right side of her neck.
• The mass was suspected to be an infection known as phaeohyphomycosis, which is a deep cutaneous or subcutaneous mycosis caused by pigmented fungi.
• To confirm the infection and identify its exact cause, histopathology was utilized in combination with Polymerase Chain Reaction (PCR) and 18S rRNA gene sequencing.
• The histopathology report confirmed the presence of the infection while the PCR and 18S rRNA gene sequencing further identified the pigmented fungi causing the infection as Pyrenophora phaeocomes and Drechslera nobleae.

Treatment and Outcome

• Once the diagnosis was confirmed, the next step was treating the mare.
• The treatment involved surgically excising, or removing, the mass.
• The surgery was successful, with clean margins obtained in the procedure indicating that all infected tissue was likely removed.
• Surgical excision is usually a curative measure, suggesting a positive prognosis for the mare post-surgery.

Significance of the Study

• This research provided valuable insights into the diagnosis and effective treatment of phaeohyphomycosis in horses – which could be useful for veterinary medicine.
• The identification of the fungi Pyrenophora phaeocomes and Drechslera nobleae as the cause of such infections could add to the understanding of equine diseases and contribute to the overall knowledge of animal mycology.
• The study also underscored the utility of combining histopathology with molecular methods like PCR and 18S rRNA gene sequencing in accurately diagnosing fungal diseases.