Tibial nerve deficits secondary to gastrocnemius musculotendinopathy in a dog

Abstract A 10‐year‐old labrador retriever presented to its primary care practice with reports of pelvic limb pain and spontaneous knuckling following an unwitnessed trauma. On neurological examination, tarsal hyperflexion, delayed proprioception and a reduced withdrawal reflex led to a neurolocalisation to the left tibial nerve or L6–S1 myelopathy. Computed tomography of the lumbar spine and pelvic limbs demonstrated enlargement of the lateral head of gastrocnemius on the affected limb with focal compression of the left tibial nerve. Ultrasonography showed loss of normal myofibrillar architecture and internal calcified foci, consistent with gastrocnemius musculotendinopathy. The dog was managed conservatively, which led to both improvement in the ultrasonographic appearance of the muscle and in the neurological examination. Gastrocnemius musculotendinopathy should be considered as a differential diagnosis for veterinary patients presenting with pelvic limb lameness alongside tibial nerve deficits.