Cervical disk disease involves degeneration of the intervertebral disks in the neck region with compression of the spinal cord or nerves. To better understand the disease and how it may affect your pet, it is first important to understand the basic anatomy and physiology of the spine.
The spinal column is made up of a number of small bones called vertebrae, which are lined up like building blocks. A hole in the center of each vertebra forms a tunnel in which the spinal cord lies. The spinal cord is extremely important because, much like a telephone cable that has many smaller wires, it transmits signals from the brain to control the internal organs, legs and muscles. As the spinal cord is extremely delicate, being surrounded by the bony vertebrae helps to protect it.
Between each pair of vertebrae – except for the first and second vertebra located in the neck – is a little cushion called an intervertebral disk. Intervertebral disks connect the vertebrae of the spinal column together and allow for smooth movement while maintaining protection of the spinal cord. These disks provide flexibility and support, and can be thought of as shock absorbers between the vertebrae. Together, the vertebrae and disks compose the vertebral column, which extends from the head to the tail of an animal. Intervertebral disks are composed of a tougher fibrous outer portion, known as the annulus fibrosus, and a gelatinous inner portion called the nucleus pulposus. The nucleus pulposus is contained within the annulus fibrosus like a jelly donut. The fluid-like characteristic of the nucleus pulposus allows for compression of the spine, providing flexibility and shock absorption without damaging the vertebrae or the spinal cord. The intervertebral disks are thus responsible for a great deal of the spinal column’s stability and mobility.
When disk degeneration occurs in the neck, the result is neck pain and spinal cord dysfunction behind the affected area. This means that if your pet suffers from this disease, it will experience pain in the neck region, and is at risk of neurological problems in all four limbs. The nerve dysfunction may manifest itself as numbness, weakness, wobbliness, and loss of control of bladder and bowel. If left untreated, it can progress to complete paralysis. The signs may come on suddenly or gradually over many months or years. This condition is known by several different names, including cervical vertebral instability, Wobbler Syndrome, cervical stenosis, and cervical spondylomyelopathy.
Wobbler Syndrome is a degenerative disease of the disks and ligaments in the neck that leads to compression of the spinal cord. Abnormalities of the spine that contribute to this condition include a narrow vertebral canal from birth; protrusion of the intervertebral disk; thickening of the ligaments above and below the spinal cord; a partial dislocation of the neck bones; and the thickening of the joints of the vertebrae.
The compression of the spinal cord may be static, meaning that movement of the neck does not change the amount of compression on the spinal cord. Other cases have a dynamic compression of the spinal cord, meaning that the amount of compression on the spinal cord changes with the position of the neck.
Whenever your pet is showing signs of a health issue your first step is to contact your primary care veterinarian. If it is indicated that your pet may suffer from cervical disk disease or another serious condition, a veterinary specialist is available at an ExpertVet certified or affiliated hospital.
Although in Wobbler Syndrome the spinal cord compression occurs in the neck, the hind legs often are affected first. The mildest form of cervical stenosis, or narrowing of the spinal canal, results in stumbling or irregular walking or running. This can progress to a wobbly gait, hence the term “Wobbler Syndrome.” In severe cases there may be total paralysis of all four limbs.
Wobbler Syndrome is usually caused by instability of one or more of the vertebrae at the base of the cervical vertebrae. It may also be due to deformity of these vertebrae, which causes pressure on the spinal cord. This compression damages the spinal cord transmitting information to the limbs and thus paresis or paralysis can occur. Initially, the increased pressure on the spinal cord affects your dog’s ability to move naturally, and it may be difficult for you to notice these subtle differences. This incoordination, however slight, can put extra stress on the intervertebral discs that act as shock absorbers. If this extra pressure causes the intervertebral discs to rupture, excess pressure is put on the spinal cord and sudden paralysis may result.
Wobbler Syndrome most commonly affects middle-aged Doberman Pinschers although other breeds can be affected as well. A similar but different syndrome is seen in young Great Danes and giant breeds such as Mastiffs. The symptoms are the same but compression develops due to premature arthritis of the vertebrae causing stenosis of the vertebral canal. Typically this is seen at a younger age, symptoms are more gradual in nature and neck pain is uncommon.