Neurofibromas in dogs are a type of cancer tumor that can form on the nerve endings of, or the peripheral part of, a dog's nervous system. They can occur on any nerve but are most commonly found in the connective nerve tissue. Some are benign and pose no threat. Many are malignant and can cause extreme discomfort and even threaten the dog's comfort life if not removed.
It Forms in the Myelin Sheath
Neurofibromas form in the myelin sheath, which is the protective encasement around the axons of nerves in the canine peripheral nervous system. This system is located outside the brain and spinal cord. Neurofibromas get their start from dysfunctional Schwann cells surrounding the nerve axon. Research conducted as recently as February 2014 indicates neurofibromas tend to form in areas of previous injury, though veterinary researchers were still studying the issue.
Pain Is a Prime Symptom
The most obvious symptom -- the one dog owners first notice -- is the canine being in severe, unexplained, uncontrollable and chronic pain. Generally, this first appears in the hind limbs before it does in the forelimbs. Dogs may experience partial loss of movement and may be unable to coordinate their muscles. Depending on the location of the tumor, dogs with neurofibromas can have droopy eyelids and partial face paralysis.
Diagnosis Can Be Challenging
Neurofibromas' interior location makes early detection challenging. Veterinary researchers believe that two to 24 months may elapse between the tumor developing and it being detected. For diagnosis, the first step is a complete physical examination followed by blood work, an electrolyte panel and urinalysis. The veterinarian most likely will ask questions regarding your dog's history prior to the onset of symptoms. The veterinarian may order a computed tomography scan or magnetic resonance imaging, or both, to document the extent and exact location of the neurofibroma.
Treatment Is Usually Surgery
Surgical removal of the neurofibroma is the treatment of choice for a large percentage of veterinarians. Recurrence is common. In cases where the tumor returns, the veterinarian may recommend amputation. When the neurofibrama is putting pressure on the spine, a laminectomy to remove a portion of the vertebral bone may be necessary. Radiotherapy, which is the use of high-energy rays to kill cancer cells, is an option available to retard growth of a small, nonthreatening neurofibroma.