Nerve Sheath Tumors in Dogs

Nerve sheath tumors are an uncommon, but potentially life-threatening condition affecting man's best friend. Capable of sprouting in benign and malignant form, it is a cancer that thankfully does not spread through the lymphatic system. Predominantly afflicting aged animals, it is imperative for proper and effective treatment that the tumor be caught in early stages.

  1. Identification

    • Nerve sheath tumors (NSTs) occur in the myelin sheath of the peripheral nervous system (the nervous system outside of the brain and spinal cord.) The tumor originates from the Schwann cells, which make up the myelin sheath, a protective coat to the actual nerve. In addition, the myelin sheath also provides mechanical and physical support to the nerve it surrounds.

    Types of Nerve Sheath Tumors

    • Nerve sheath tumors are called by many different names including neurofibromas, neurofibrosarcomas and schwannomas. However, the difference in name is largely dependent upon the location of the tumor, since all of the tumors are presumed to originate in the Schwann cells surrounding the nerve axon.

    Cause of Nerve Sheath Tumors

    • The cause of nerve sheath tumors is stated as being idiopathic, which means no definitive reason is known. However, NSTs tend to be more common around areas of former injury. The Schwann cells that NSTs originate from partly function to help repair and restore damaged nerve tissue. The tumorous growth is thought to be associated with this restorative process; however, the exact link is still unknown.

    Symptoms

    • According to PetMD, the symptoms of nerve sheath tumors include chronic, progressive forelimb lameness; lameness in hind limbs; peripheral nerve disorder; palpable mass; droopy eyelid; one-sided facial paralysis; decreased pupil size.

    Rate of Occurrence

    • Compared with other carcinomas affecting the canine population, there is a low risk of your pet contracting a nerve sheath tumor. Most often, older dogs are affected. However, due to the similarity of symptoms between NSTs and other geriatric canine ailments, it is often difficult to diagnose in early stages.

    Treatment

    • The most common prescribed treatment for a nerve sheath tumor is surgical removal of the tumor. Often amputation is required due to the inability to catch the tumor in early stages and the high likelihood of re-occurrence (72 percent.) The closer to the paw the NST has developed, the greater the chance of complete recovery in the canine.