Lameness originating from the proximal metacarpus/tarsus: A review of local analgesic techniques and clinical diagnostic findings

Abstract

Summary Accurate diagnosis of conditions of the equine proximal metacarpus and metatarsus presents a clinical challenge. Diagnostic analgesia of this region is nonspecific, which may lead to incorrect interpretation of blocking patterns, potentiating incorrect diagnoses and treatment. Results of local analgesia should be examined carefully during clinical lameness evaluations due to the possibility of diffusion of local anaesthetic solution and inadvertent intrasynovial injection. Supplementary diagnostic analgesia of surrounding anatomic regions and advanced diagnostic imaging, particularly magnetic resonance imaging, are recommended for most accurate diagnosis of lameness. Failure in response to therapy in cases where supplementary diagnostic analgesia and advanced diagnostic imaging have not been performed should prompt the clinician to broaden the approach to better characterise the site of pain.

Outcome following neurectomy of the deep branch lateral plantar nerve and plantar fasciotomy for hindlimb proximal suspensory desmopathy in western performance horses: 21 cases

“…All horses had an abnormal appearing PSL at ultrasonographic examination, with enlargement of the PSL a consistent ultrasonographic feature 12 . However, a false positive result after PSL diagnostic analgesia is well recognized because of potential diffusion of adjacent soft tissue or synovial structures, such as the lower tarsal joints or tarsal sheath 14 . Comorbidity with other hind limb pathologies may have partially influenced outcome results of this study.…”

“…Twenty-one horses in western performance disciplines underwent DBLP neurectomy/ fasciotomy consisting of 16 quarter horses and five paints, which included 13 geldings, seven mares, and one stallion. The median age at time of diagnosis and subsequent surgery was 8 years (range, [3][4][5][6][7][8][9][10][11][12][13][14]. Western disciplines included western pleasure (14/21), barrel racing (2/21),…”

Standing low‐field MRI of the equine proximal metacarpal/metatarsal region is considered useful for diagnosing primary bone pathology and makes a positive contribution to case management: A prospective survey study

“…Finding the cause of proximal metacarpal/metatarsal pain can be challenging due to the lack of specificity of local analgesic procedures, the composition and topography of the suspensory ligament, and difficulties acquiring high-quality diagnostic ultrasonographic images. 3,13 When applied to this region, users associated standing low-field MRI with a considerable impact on case management, particularly in the face of equivocal primary diagnostic findings and poor initial treatment responses. However in support of our hypothesis, detection of standing low-field MRI abnormalities was felt to be dependent on the horses' type or use, with general purpose riding horses less likely to present with detectable abnormalities.…”

“…Accurate diagnosis of pain causing lameness in the proximal metacarpal or metatarsal region can be challenging due to the complexity of interpreting results of diagnostic analgesia and the potential absence of abnormal radiographic or ultrasonographic findings . In particular, the diagnosis of suspensory ligament disease requires considered use of all available diagnostic tools including MRI and this is facilitated by detailed knowledge of the region's normal MRI appearance .…”

Letter to the Editor: Regarding recent paper by Pezzanite et al.

“…The recent paper by Pezzanite et al (2020) raised a variety of important points concerning the challenges of accurate diagnosis of proximal metacarpal and metatarsal region pain. We would like to enlarge on some aspects of the clinical investigation.…”