Objectives: This study aims to evaluate the distribution and severity of bone and soft tissue lesions in the proximal metacarpal region of warmblood horses in lame and control groups. Correlation between lesions and ability to return to work was evaluated in the lame group.Methods: This restrospective analysis evaluated 62 horses with MRI examination of the proximal metacarpal region between Sept 2015 and Feb 2021. There were 36 lame limbs and 26 control limbs. The control group included seven contralateral limbs.Results: Proximal suspensory ligament (PSL) size was not different between the lame and control groups. Hyperintensity seen on T1W/T2*W GRE images within the dorsal collagenous part of the PSL and hyperintense Short-TI Inversion Recovery (STIR) signal within the dorsal collagenous part of the PSL or within the McIII were only present within the lame group. Palmar cortical McIII resorption and dorsal margin irregularity of the PSL and McIII sclerosis were more severe within the lame limbs, but mild gradations were also seen in control limbs. Intermediate gradings for a subset of lesions were commonly seen in the non-lame contralateral to lame limbs. Return to work in the lame group is not statistically different for any measured observation(s), and 19/33 of the lame horses returned to work at similar or higher levels.Conclusion and clinical importance: Fifty-eight percent in this group of warmblood horses returned to work within a variable time frame. The majority (81%) of lame limbs showed bone and soft tissue abnormalities, but no enlargement of the PSL was noted in lame horses, and no correlation was seen between the severity or type of lesions and the ability to return to work. The presence of STIR hyperintensity within the proximal McIII or dorsal collagenous part of the PSL and hyperintensity within the dorsal collagenous part of the PSL on T1W GRE and T2*W GRE images, as well as significant palmar cortical McIII resorption are considered clinically relevant lesions. Contralateral limbs may not truly represent the normal condition, showing nonclinical variations and adaptive remodeling.

Distal sesamoidean ligament (DSL) injury is a recognized cause of lameness in horses. The purpose of this study was to describe the contrast-enhanced computer tomography (CE-CT) findings in horses with injury to the DSL compared to a control group without injury to the DSL. Medical records of horses referred for CE-CT between 2008 and 2015 were reviewed. Cases were selected retrospectively based on a CE-CT imaging finding of injury to the DSL. Three horses had DSL injury as the only finding, while the remaining horses had one or more concomitant injuries. DSL injury and fetlock trauma and/or suspensory branch desmitis were the most frequent injury combinations. CE-CT can be of value in diagnosing DSL injury. The high number of concurrent DSL and fetlock and/or suspensory lesions suggests that further investigation should be considered when evaluating horses with injuries related to either of these structures.