Neoplasia of the Peripheral Nerves and Neuromuscular Junction in Animals

Nerve sheath tumors can occur in most domestic animals but are most common in dogs and cattle. In dogs, nerve sheath tumors commonly arise from the brachial plexus or trigeminal nerve (see trigeminal nerve sheath tumor image). In cattle, nerve sheath tumors commonly arise from the vestibulocochlear nerve. For more information, see Neoplasia of the Nervous System.

Trigeminal nerve sheath tumor, dog

Image

Dog with a trigeminal nerve sheath tumor. Note atrophy of the right temporalis and masseter muscles and loss of sensation in the face on the right side, consistent with a lesion of the right trigeminal nerve.

Also see Paraneoplastic Disorders in Small Animals.

Paraneoplastic neuropathy in animals is associated with neoplasia unrelated to tumor infiltration of nerves.

Paraneoplastic neuropathy in animals has been associated with a variety of tumors, including bronchogenic carcinoma, multiple myeloma, sarcoma, and adenocarcinoma. In dogs, paraneoplastic neuropathy is most commonly reported in patients with insulinoma. In dogs and cats, as is the case for other species, acquired myasthenia gravis can occur as a paraneoplastic syndrome associated with a thymoma.

The pathogenesis of paraneoplastic neuropathy is not well understood; however, it could be related to an immune response directed against the tumor that cross-reacts with nerve components.

Clinical signs of paraneoplastic neuropathy include paraparesis or tetraparesis that progresses over several weeks, as well as decreased spinal reflexes and muscle atrophy.

Diagnosis is based on identification of the underlying tumor, clinical and electrodiagnostic findings consistent with neuropathy, and, in some cases, nerve biopsy results.

Successful treatment of the underlying tumor can potentially improve clinical signs of paraneoplastic neuropathy.

• Also see pet owner content regarding neoplasia of the peripheral nerves and neuromuscular junction in dogs and cats.