Proliferative tenosynovitis in Brazilian Mangalarga Marchador horses.

The study describes proliferative tenosynovitis (PT), a type of inflammation and proliferation disorder of the synovial membrane in tendon sheaths, identified in three Brazilian Mangalarga Marchador horses, marking the first documentation of this condition in the horse species.

Research Objective and Process

• The researchers conducted a study on proliferative tenosynovitis (PT) in horses, a condition that was not previously identified in this species. PT is an inflammation and growing disorder that affects the synovial membrane of the tendon sheath, a structure that permits smooth movements of the tendons.
• The goal of this research was to better comprehend this relatively rare disease in animals. To do so, the team analyzed the necropsy and biopsy records of horses presented to the Universidade Federal Rural do Rio de Janeiro from January 2017 to December 2020, aiming to find any potential cases of proliferative tenosynovitis within the records.

Findings of the Study

• Three adult Brazilian Mangalarga Marchador horses having nodular lesions on various joints were identified with PT.
• All three horses were younger than six years old, showing symptoms of lameness and pain upon palpation, common symptoms of an inflammation or disorder in the locomotor apparatus.
• Two of the horses experienced repeated occurrence of the condition after surgical removal, indicating a potential issue with surgical treatment or the resilience of this condition.
• Using radiographic and ultrasound examinations, the researchers detected masses in the flexor or extensor tendons and subtendinous bursa of the affected animals.
• A histological study, which involves microscopic examination of tissue, of the synovial membrane and the tendon sheath, revealed an elevated number of vessels, increased connective tissue growth (fibroplasia), bone tissue formation in normally non-osseous tissues (osseous metaplasia), and infiltration of lymphocytes, plasma cells, and siderophages.

Conclusions and Implications

• This study is the first one to describe the occurrence of PT in horses, significantly contributing to the understanding of rare equine conditions and enhancing the available literature on equine health matters.
• The authors recommend, based on the findings, that PT should be included as part of the differential diagnosis when treating lameness, particularly in Mangalarga Marchador horses.
• The discovery of this condition in horses provides new avenues for continuing research on PT in animals, with future studies potentially focusing on possible causes, improved treatments, and preventative measures.