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Veterinary dermatology2026; doi: 10.1111/vde.70101

Cutaneous Equine Sarcoidosis: A Case Series and Investigation Into a Potential Association With Equine Gammaherpesviruses-2 and -5 in 30 Equids.

Abstract: Gammaherpesviruses have been associated with granulomatous inflammation in the skin of various species. Equine sarcoidosis (idiopathic granulomatous disease) can cause granulomatous dermatitis, and its cause remains unknown. Objective: This retrospective study aimed to investigate the possible association between equine gammaherpesviruses-2 and -5 (EHV-2, -5) and cutaneous equine sarcoidosis (cES). Methods: Thirty client-owned equids. Methods: All animals had histologically and clinically confirmed cES. Signalment, geographical location and clinical features were recorded. Gram, Ziehl-Nielsen and Grocott-Gömöri methenamine silver histochemical stains, quantitative (q)PCR and in situ hybridisation were performed on formalin-fixed paraffin-embedded tissue samples. Results: Quarter horses and thoroughbreds were overrepresented, and ages ranged from 10 months to 31 years old, with minimal difference in sex distribution. Localised, partially generalised, and generalised forms were noted in 13, 11 and six animals, respectively. The most common lesions were alopecia, crust and scale, and the limbs were the most affected site. Neither bacteria nor fungi were detected with histochemical stains. EHV-5 and -2 DNA were detected by qPCR in eight and four of 30 animals, respectively. Of those eight horses, EHV-5 hybridisation signals were found within skin lesions of five. ISH did not detect EHV-2 in any of the 29 animals tested. Conclusions: Although the exact cause of sarcoidosis remains uncertain, these findings suggest that EHV-5 may play some role in the pathogenesis of cES. This study also reports a single case of cES in a donkey.
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Publication Date: 2026-07-03 PubMed ID: 42399093DOI: 10.1111/vde.70101Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study investigated whether two types of equine gammaherpesviruses (EHV-2 and EHV-5) are linked to cutaneous equine sarcoidosis (cES), a skin disease characterized by granulomatous inflammation in horses and donkeys.
  • Researchers analyzed clinical data and tissue samples from 30 affected equids to identify the presence of these viruses and their potential role in the disease.

Background and Purpose

  • Granulomatous inflammation is a type of immune response seen in various species and can be linked to infections by gammaherpesviruses.
  • Cutaneous equine sarcoidosis (cES) presents with granulomatous dermatitis, but its cause is currently unknown.
  • The main goal was to explore a possible association between cES and equine gammaherpesviruses types 2 and 5 (EHV-2 and EHV-5).

Study Design and Methods

  • Retrospective analysis of 30 client-owned equids diagnosed with cES both clinically and histologically.
  • Data collected included the breed, age, sex, geographical location, and clinical features of the affected animals.
  • Skin tissue samples fixed in formalin and embedded in paraffin were analyzed using:
    • Histochemical stains: Gram stain for bacteria, Ziehl-Nielsen for acid-fast bacteria, and Grocott-Gömöri methenamine silver stain for fungi.
    • Quantitative PCR (qPCR) to detect viral DNA of EHV-2 and EHV-5.
    • In situ hybridisation (ISH) to localize viral genetic material within tissue lesions.

Findings

  • Breed distribution showed overrepresentation of Quarter Horses and Thoroughbreds.
  • The age range of affected equids was broad, from 10 months to 31 years, with a balanced sex distribution.
  • Clinical presentation varied:
    • Localized lesions in 13 animals.
    • Partially generalized lesions in 11 animals.
    • Generalized lesions in 6 animals.
  • Common clinical signs included alopecia (hair loss), crusting, and scaling, with the limbs being the most commonly involved sites.
  • Histochemical staining showed no evidence of bacterial or fungal infection in any cases.
  • Viral DNA detection results:
    • EHV-5 DNA was found in 8 out of 30 animals by qPCR.
    • EHV-2 DNA was found in 4 out of 30 animals by qPCR.
  • In situ hybridisation results:
    • EHV-5 signals were present within skin lesions in 5 of the 8 qPCR-positive cases.
    • EHV-2 was not detected by ISH in any of the 29 animals tested.
  • The study also included the first reported case of cES in a donkey.

Conclusions and Implications

  • The exact cause of cutaneous equine sarcoidosis remains unclear.
  • The detection of EHV-5 within skin lesions suggests this virus might contribute to the development or progression of cES.
  • The absence of bacteria and fungi supports the non-bacterial, non-fungal nature of the disease.
  • EHV-2 appears less likely to be involved as its genetic material was not localized within lesions despite some DNA detection.
  • These findings provide a basis for further research on the role of EHV-5 in equine skin granulomatous diseases and may guide future diagnostics or treatments.

Cite This Article

APA
Garandeau C, Champion CP, Lejeune M, Peters-Kennedy J. (2026). Cutaneous Equine Sarcoidosis: A Case Series and Investigation Into a Potential Association With Equine Gammaherpesviruses-2 and -5 in 30 Equids. Vet Dermatol. https://doi.org/10.1111/vde.70101

Publication

Veterinary dermatology
ISSN: 1365-3164
NlmUniqueID: 9426187
Country: England
Language: English

Researcher Affiliations

Garandeau, Celine
  • Department of Clinical Sciences, Cornell University, College of Veterinary Medicine, Ithaca, New York, USA.
Champion, Christopher P
  • Department of Population Medicine and Diagnostic Sciences, Cornell University, College of Veterinary Medicine, Ithaca, New York, USA.
Lejeune, Manigandan
  • Department of Population Medicine and Diagnostic Sciences, Cornell University, College of Veterinary Medicine, Ithaca, New York, USA.
Peters-Kennedy, Jeanine
  • Department of Population Medicine and Diagnostic Sciences, Cornell University, College of Veterinary Medicine, Ithaca, New York, USA.

Grant Funding

  • Harry M. Zweig Memorial Fund for Equine Research
  • 180291 / American College of Veterinary Dermatology
  • Danny W. Scott

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This article includes 31 references
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