Generalized sarcoidosis associated with hypertrophic osteopathy in a Standardbred racehorse.
Authors: Charles A, Kerckhove H Vande, De Maré L, Cassart D, Ficheroulle J, Pouyade G de la Rebière de, Tosi I
Journal: Journal of equine veterinary science
Summary
# Editorial Summary A Standardbred racehorse presented with a constellation of clinical signs—exercise intolerance, weight loss, fever and facial swelling—that prompted imaging investigation and ultimately revealed a rare concurrent diagnosis of equine sarcoidosis with secondary hypertrophic osteopathy. Beyond the initial maxillofacial deformities documented on radiography and ultrasound, the horse developed characteristic periostitis and soft tissue swelling in the distal limbs alongside cutaneous lesions during hospitalization; skin biopsies confirmed granulomatous dermatitis, whilst post-mortem examination identified splenomegaly, pulmonary nodules and disseminated granulomatous lesions throughout thoracic tissues. The hypertrophic osteopathy—a paraneoplastic-type phenomenon typically secondary to chronic intrathoracic disease—likely arose from the underlying pulmonary pathology associated with generalized equine sarcoidosis (also termed idiopathic systemic granulomatous disease), with PCR analysis detecting equine herpesvirus 5 DNA in pooled tissues, suggesting a possible infectious trigger. This case is noteworthy for practitioners because the concurrent presentation of HO with systemic granulomatous disease is exceptionally uncommon, and the radiographic appearance of bilateral, symmetrical periostitis affecting multiple skeletal sites should prompt consideration of underlying systemic pathology rather than localised orthopaedic conditions. Early recognition of such presentations and investigation of intrathoracic involvement may allow more timely diagnosis, though the rapid clinical deterioration in this case underscores the aggressive nature of disseminated equine sarcoidosis.
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Practical Takeaways
- •Recognize that hypertrophic osteopathy in horses may indicate underlying systemic disease rather than primary skeletal pathology; investigate pulmonary and visceral involvement
- •When facial deformity, exercise intolerance, and distal limb periostitis occur together, consider generalized sarcoidosis as a differential diagnosis requiring skin biopsy for confirmation
- •EHV-5 infection may be associated with systemic granulomatous disease in horses; PCR screening of affected tissues should be considered in suspected cases
Key Findings
- •Concurrent presentation of equine sarcoidosis and hypertrophic osteopathy in a single Standardbred racehorse with systemic manifestations
- •Histopathology revealed disseminated granulomatous lesions affecting skin, lungs, spleen, and skeletal tissues
- •PCR testing identified equine herpesvirus 5 (EHV-5) DNA in pooled tissue samples
- •Intrathoracic pulmonary pathology was likely responsible for triggering secondary hypertrophic osteopathy