Generalized sarcoidosis associated with hypertrophic osteopathy in a Standardbred racehorse.

This research investigates a case of a Standardbred racehorse that developed generalized sarcoidosis (an inflammatory disease affecting multiple organs) and hypertrophic osteopathy (abnormal bone growth or swelling), manifested through physical impediment, weight loss and fever. The diagnosis was confirmed via various tests including radiography, ultrasonography and computed tomography, with identification of an equine herpesvirus (EHV-5) potentially being linked to the condition.

Case Presentation and Diagnostic Measures

• The study shares a case of a racehorse that started showing multiple signs of illness including exercise intolerance, weight loss, fever, and facial deformity.
• The team employed radiography and ultrasonography which exposed abnormal bone growth (periostitis) and regional tissue swelling in the horse’s maxillary (upper jaw) bones.
• Dental or sinus origins of these abnormalities were excluded through computed tomography.
• Additional deformities on the limbs, and skin lesions developed during the horse’s hospital stay.
• Radiographs identified similar periostitis and tissue swelling in the distal radius and metatarsal bones of the limbs, pointed towards a possibility of hypertrophic osteopathy.

Sarcoidosis Diagnosis and Post Mortem

• Skin biopsies revealed granulomatous dermatitis, an indicator of equine sarcoidosis, a skin disease caused by an abnormal immune response.
• The horse’s condition rapidly worsened leading to euthanasia. On examination after death, the horse was found to have an enlarged spleen (splenomegaly), numerous lung nodules, and spread out granulomatous lesions.
• The post-mortem presentation and histopathological examinations confirmed the diagnosis of generalized equine sarcoidosis (also known as equine idiopathic systemic granulomatous disease), implying the disease was widespread across multiple organs.

Association with a Virus

• The association of hypertrophic osteopathy was believed to be linked to the noted pathology in the thorax (chest region).
• Furthermore, polymerase chain reaction tests on the horse’s tissues identified the presence of equine herpesvirus 5 (EHV-5) DNA, suggesting a possible connection between the virus and the horse’s disease.