Our doctors at the Animal Clinic at Thorndale frequently see dogs with a variety of orthopedic and neurological problems.The term “wobbler” originated from a spinal disease of horses that causes incoordination while walking. The canine version is more appropriately known as Caudal Cervical Spondylomyelopathy. It results in a wobbly gait when walking or running due to pressure on the spinal cord in the lower part of the neck.
Prevalence
Great Danes and Doberman pinchers are the commonly affected breeds, but any large breed is at risk for this disorder. Great Danes are usually affected when they are young, about 1-3 years of age. Doberman pinchers and other breeds are typically 6-9 years of age when the symptoms begin. Slightly more males than females are affected.
Causes/Transmission
The exact cause of this disorder is unknown, but genetics, overnutrition, and conformation problems have all been considered as possible contributing factors. Regardless of the cause, the end result is that either bones or ligaments in the neck develop malformations that lead to compression on the spinal cord.
In Great Danes, the spinal canal is thought to actually narrow due to bony malformations on the cervical vertebrae. In Dobermans, it is thought to result from instability between two or more vertebrae in the lower part of the neck. When instability exists, the body attempts to correct the problem. This results in a thickening of the ligaments that are within the joint; one is above the spinal cord and two are below it. As these ligaments thicken, they put pressure on the spinal cord. Also, an intervertebral disk (cushion between the vertebrae) may put pressure on the spinal cord, adding further compression.
The spinal cord is much like a large telephone cable that contains thousands of wires, each carrying important messages. When the telephone cable is crushed, the tiny wires within are broken so they cannot transmit information. A similar event occurs when the spinal cord is compressed by the thickened ligaments, bony protrusions from the vertebrae, or a disk. They are unable to carry messages from the brain to the nerves in the legs, so the legs cannot move as they should.
Clinical Signs
The pressure on the spinal cord from the thickened ligaments causes the dog to walk in a very uncoordinated fashion. The hind limbs are invariably more affected than the front limbs. Many of these dogs are initially seen to stumble; this progresses to “wobbling” in the hind limbs. The owner may hear the dog drag the toenails of the rear legs or note that the surfaces of the toenails are excessively worn. Eventually, this dragging motion becomes more apparent. There may be rigidity or a spastic tone to the front legs. Interestingly, neck pain is not typical of this disorder.
In most cases, the deterioration is slowly progressive. Rarely, an acute (sudden) trauma may lead to rapid deterioration of neurologic function. When there is a sudden decompensation of the animal, a ruptured disk is most likely.
Diagnosis
Radiographs (x-rays) of the neck often reveal that the cervical vertebrae are not properly aligned. If the dog is the right breed and the symptoms are correct, this provides strong evidence of the wobbler syndrome. However, plain radiographs do not show the spinal cord so the presence of pressure on it cannot be proven in this manner. A myelogram is a radiograph made after a special contrast material (dye) is injected around the spinal cord to demonstrate the site of compression. This procedure is still available in a few veterinary facilities, but most hospitals will now recommend an MRI. An MRI gives detailed look at the spinal cord and its surroundings, often without the injection of dyes. A CT scan can also give a better look at boney structures in the neck. Procedures such as MRI and CT Scan require general anesthesia.
Treatment
Anti-inflammatory drugs and pain relievers are often prescribed in the early stages of this disease. They may provide some relief from the symptoms, but this improvement is only temporary. As the disease progresses, medication will no longer be helpful. Special precautions must be taken when pain relievers and anti-inflammatory medications are given to Doberman Pinschers as there is a very high incidence of inherited bleeding disorders in this breed; some medications may precipitate a bleeding crisis. Also, diminished thyroid function is common in Dobermans. Supplementation with synthetic thyroid medication may be helpful in selected cases.
Successful treatment requires that the pressure be removed from the spinal cord. In some dogs, a specially fashioned neck brace can be helpful in limiting motion in the neck. This can be helpful for awhile. However, many dogs eventually progress to the point that surgical intervention is required. There are several surgical procedures that have been used, but none have been successful in all cases. The findings on the MRI are used to determine the surgical procedure that is most likely to be helpful.
Post-operative Care
The degree of after care will depend on the dog’s ability to walk at the time it goes home from the hospital. If it can walk, but it is uncoordinated, it will need assistance so that a fall does not occur. If it is still paralyzed at the time of discharge, the amount of after care can be considerable because of the dog’s weight. If you are not able to lift your dog and you do not have someone else who can help you do so, you should discuss this situation before you opt for surgery.
Prognosis
Regardless of the treatment option chosen, the overall prognosis is guarded for dogs with Wobbler syndrome. If surgical therapy is to offer improvement, it must be performed early in the course of the disease.