Bilateral obturator neuropathy caused by an intrapelvic fibrosarcoma with myofibroblastic features in a dog

Abstract

A nine-year-old female Rottweiler presented with a 6-week history of progressive impairment of hindlimb adduction. Clinical examination showed abduction of both hind legs when walking on a smooth surface, pain at the medial surface of the left thigh, and an intrarectal palpable mass at the pelvic floor. Electromyography demonstrated fibrillation potentials in the adductor muscles on both sides. Pelvic radiographs showed severe osteolysis of the ischium. Gross post-mortem examination following euthanasia disclosed a large retroperitoneal mass, invading the obturator foramina and compressing both obturator nerves. Histopathological examination revealed a high-grade anaplastic sarcoma. Immunohistochemically, the tumour cells labelled positively for vimentin and alpha-smooth muscle actin, hence the tumour was considered a "myofibroblastic fibrosarcoma". This unique case report describes a novel cause of obturator neuropathy in veterinary medicine. To date, clinical descriptions of obturator nerve lesions have been limited to pelvic fractures in small animals and following difficult labour in large animals.

Mid-to-caudal partial hemipelvectomy with limb preservation for ischial tumor in a dog

“…Circumduction and wide-based gait caused by abnormal abduction during ambulation have been reported in dogs and humans with obturator neuropathy [4,11]. A dog with bilateral obturator neuropathy showed instability in standing up and walking on a slippery surface [11]. In this case, frequent outward stepping of the hindlimb when walking on slippery surfaces and wide-based gait were observed after surgery.…”

“…There is limited research on obturator nerve resection and hindlimb preservation in humans and dogs. Circumduction and wide-based gait caused by abnormal abduction during ambulation have been reported in dogs and humans with obturator neuropathy [4,11]. A dog with bilateral obturator neuropathy showed instability in standing up and walking on a slippery surface [11].…”

Evaluation of proximal and distal motor nerve conduction using the electrical root stimulation technique in the femoral and obturator nerves

“…The most common factors are temperature, age, height, and the method used for the measurement of distance (27). The age of an animal has a degenerative diseases such as some inherited polyneuropathies (3,9,10). Electroneuromyography provides a tool to measure the physiological integrity of the nerves and nerve roots, and is currently used as an aid to diagnosis in veterinary medicine and before more invasive tests such as nerve biopsy (11).…”

“…As the obturator nerve courses on the medial surface of the ilium, it is at risk for injury with iliac fractures. Obturator nerve damage has been reported as a possible complication in triple pelvic osteotomy, and intrapelvic fibrosarcoma in dogs (9,10). Electrophysiological investigations are the most important tools used to confirm the diagnosis of nerve damage (11).…”

“…Electrophysiological investigations are the most important tools used to confirm the diagnosis of nerve damage (11). However, techniques for studying motor and sensory conduction and normative data for both the obturator and femoral nerves are not reported in veterinary medicine (10). The motor nerve conduction velocities of the femoral and obturator nerves obtained from healthy dogs can be useful in the investigation of polyneuropathies.…”