Bone oedema-like lesion is characterized by hyperintense signals in short tau inversion recovery (STIR) sequences on magnetic resonance imaging (MRI). The pattern of bone oedema-like lesions involving the enthesis of the collateral ligament (CL) of the distal interphalangeal joint (DIPJ) has not been investigated as a cause of lameness in horses. This pattern was detected in 10 forelimbs of nine horses, involving the medial collateral fossa of the distal phalanx in six feet. The STIR signal was graded as ‘severe’ in two feet, ‘moderate’ in two feet, and ‘mild’ in six feet, and involved the dorsal two-thirds of the fossa in seven feet. The bone lesion was the only lesion in six feet, while in three feet, the ipsilateral CL presented abnormalities. Follow-up MRI was available for three horses and revealed a reduction of the STIR signal. Five horses returned to a lower level of athletic activity, while four returned to the same or a higher level. Bone oedema-like lesion at the CLs enthesis is a potential cause of lameness even if the ipsilateral CL appears normal. The prognosis for return to athletic activity is good, although further studies with a larger number of horses are required.