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Investigation into the Potential Association of Equine Gammaherpesviruses and Cutaneous Equine Sarcoidosis

Fellow: Celine Garandeau

Mentor: Jeanine Peters-Kennedy

Department of Population Medicine and Diagnostic Sciences
Sponsor: Research Grants Program in Animal Health
Title: Investigation into the Potential Association of Equine Gammaherpesviruses and Cutaneous Equine Sarcoidosis
Project Amount: $7,570
Project Period: January 2025 to December 2025

DESCRIPTION (provided by applicant):

Equine gammaherpesviruses are commonly found in healthy horses worldwide. Although most horses are asymptomatic, equine herpesvirus 2 (EHV2) has been associated with granulomatous nodular dermatitis in one horse and EHV5 has been associated with equine multinodular pulmonary fibrosis (EMPF) and interface dermatitis on the face of horses. Equine sarcoidosis is a granulomatous skin condition of horses that can cause exfoliative dermatitis and nodular skin disease. Because gammaherpesviruses have been associated with granulomatous inflammation and because the cause of sarcoidosis is unknown, in this study we want to investigate a potential association between equine gammaherpesvirus and cutaneous sarcoidosis. Our plan is to identify approximately 25 cases of equine cutaneous sarcoidosis from our pathology archives. We will use formalin-fixed paraffin-embedded tissue, extract DNA, and test for EHV2/5 using polymerase chain reaction (PCR). We will use the shared pathology research lab to perform this work. Because DNA extraction from formalin-fixed tissue can be difficult, we will also perform in situ hybridization {ISH) for EHV2/5 through the Animal Heath Diagnostic Center. Because fungal infections and mycobacteria spp. have been associated with granulomatous skin disease in horses, we will also perform special histochemical stains on each case  including Gram (for bacteria), Gomori methenamine silver (for fungi) and Ziehl Neelsen (for acid fast bacteria). We will identify 10 non-sarcoidosis cases of skin disease in equids and 10 samples of normal equine skin that can be used as controls.