One of the more catastrophic ailments that can affect your large-breed dog is a condition known as Wobbler Syndrome, or clinically as cervical vertebral instability.
This syndrome occurs when the spinal cord is compressed in the cervical (neck) area. This compression, or pinching, happens because the vertebra through which the cord passes is malformed or misaligned. The compression injures the part of the spinal cord that's necessary for an animal to stand and/or move normally.
What causes these deformities in the vertebrae isn't yet known, but it is believed to be related to both genetics and nutrition. In some young dogs, Wobbler can develop if the animal is fed a diet excessively high in protein, calcium and phosphorus, in an attempt to accelerate the growth process. This is believed to cause the skeletal changes that occur in some affected dogs.
In most cases of Wobbler, the dog's spinal canal is narrow and short, compressing the spinal cord slightly, and worsening when the neck is extended. In other cases, the vertebrae "overgrow" and extend into the area designed for the spinal cord (the spinal canal). Also, the vertebrae may be abnormally shaped, or else the joints between the vertebrae are malformed. In all these cases, the spinal cord can become caught between structures and compressed. In Doberman Pinschers and Great Danes, the skeletal abnormality responsible for Wobbler syndrome usually occurs in the last three vertebrae in the neck (the fifth, sixth and seventh cervical vertebrae).
In all these cases, the abnormalities place constant stress on the cushioning discs between the vertebrae, causing them to degenerate and eventually rupture, creating additional pressure on the spinal cord.
Although it's primarily found in young Great Danes and older Doberman Pinschers, Wobbler syndrome can occur in any dog, even some smaller breeds like Beagles and Bassett Hounds. It's usually diagnosed through radiographs and a myelogram, a study of the spine which uses an injected contrasting dye to allow the veterinarian to examine where the compression is located, its severity and any resulting swelling of the spinal cord.
Affected animals will develop symptoms rapidly, starting with weakness and a lack of coordination, especially in their hind limbs. These symptoms usually worsen gradually over several weeks or months. The dog often will stand with its hind legs wider apart than normal, causing its hindquarters to sway back and forth. Or, the dog's hind legs may not fully extend, causing it to assume a crouched posture with its toes scuffing on the ground at every step. Usually the front legs are not affected, but occasionally they may be stiff and awkward as well. The good news is that the condition is not painful, and the animal will remain alert and responsive.
Treatment for these dogs usually begins with corticosteroid injections to reduce any swelling of the spinal cord. This is a temporary measure, and normally is followed by surgery to relieve the pressure on the spinal cord and possibly repair some of the vertebral malformations. The most common surgical method is to remove any ruptured discs and then reinforce the remaining vertebra. Most dogs that were still able to walk prior to surgery do well after the procedure; the prognosis is more guarded for dogs that were paralyzed and/or unable to stand prior to treatment. Most dogs do experience improved functioning; however the longterm outlook depends upon how much permanent damage has been done to the spinal cord.