Developmental orthopaedic disease and early osteoarthritis of the temporomandibular joint in a 15-month-old Quarter Horse filly

A 15-month-old Quarter Horse filly presented for evaluation of hard swellings over the left temporomandibular joint (TMJ) and the right metatarsophalangeal joint (MTPJ). The TMJ swelling had been noted since she was weaned at 4 months of age and had slowly enlarged since then. Radiographs of both TMJs and the right MTPJ were performed, which revealed severe osteoarthrosis associated with osteochondrosis-like lesions. The filly was subjected to euthanasia due to the poor prognosis for performance. Computed tomography and post-mortem examination, including histopathology of the left TMJ, revealed early osteoarthritis (OA) associated with osteochondrosis-like lesions of the left TMJ and the right MTPJ, while the right hind proximal interphalangeal joint (PIPJ) was diagnosed with early OA.

Automated summary

A 15-month-old Quarter Horse filly presented with hard swellings over the left temporomandibular joint (TMJ) and right metatarsophalangeal joint (MTPJ), which were found to be severe osteoarthrosis with osteochondrosis-like lesions. The filly was euthanized due to poor prognosis, and post-mortem examination revealed early osteoarthritis associated with osteochondrosis-like lesions in the TMJ and MTPJ joints. Early OA was also diagnosed in the right hind proximal interphalangeal joint (PIPJ).