Magnetic resonance imaging findings in three Warmblood horses with osteoarthritis of the distal interphalangeal joint

Summary Osteoarthritis (OA) of the distal interphalangeal joint (DIPJ) can significantly affect horse performance and overall health. This article discusses three cases of a rare form of OA in the DIPJ, involving the palmar distal condyles of the middle phalanx and the dorsal articular surface of the navicular bone, as seen on MRI. Lesions of the flexor fibrocartilage surface of the navicular bone have been described in the literature; however, focal hyaline cartilage loss from the opposite articular surfaces of the navicular bone and the middle phalanx has not been reported as a manifestation of OA in the DIPJ. The loss of hyaline cartilage from this location has been clearly defined on MRI images, confirming that standing low‐field MRI is an accurate diagnostic tool for identifying this type of OA in the DIPJ. This condition has a poor prognosis for athletic performance as none of the horses described in this report resumed their previous athletic activity, despite several conservative and/or surgical treatments.