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Posts Tagged ‘Spinal cord’

This is a condition seen most commonly in tall, long necked horses and large breeds of dogs, particularly Great Danes and Dobermans. The disease is characterized by an abnormal gait in the front and/or the hind legs. The animal seems to “wobble” when walking or exercising. Some animals seem to have a stiff neck, may appear to be weak or lazy, that is reluctant to move, stumble more than normal or seem to misstep. There may be a generalized unsteadiness, hindquarter weakness or knuckling over in the lower leg joints, particularly in the hind limbs.

The term is frequently applied to several different abnormalities resulting in ataxia, defined as a proprioceptive deficit (loss of sense of where the animal places his or her feet). In advanced cases, the animal may fall as it struggles to ambulate. In horses, it includes a specific condition known as Equine wobbles anemia. There is considerable controversy about the potential genetic nature of Equine wobbles anemia. Other specific conditions that can result in the same set of signs include at least three different malformations of the cervical (neck) vertebrae; protrusion of an intervertebral disc, disease of the interspinal ligaments or of the articular facets (the joints) of the vertebrae in the neck. Other names for this condition are; cervical vertebral instability, cervical spondylomyelopathy and cervical vertebral malformation. The condition can also be the result of a brain lesion.

The most common cause in both dogs and horses is spinal cord compression from one of the various cervical vertebral malformations, which, again, may or may not, be inherited. Spinal cord compression can be either dynamic, occurring only when the animal bends or extends its neck, or static, present all the time.

To make a definitive diagnosis your veterinarian will have to do a complete neurological exam and then radiographs (X-rays) of the spinal canal including a contrast study (myelogram). The radiographic studies will have to be conducted with the animal under general anesthetic. While conducting these tests your veterinarian will also rule out the possibility of an infectious agent or a traumatic injury by examining the cerebrospinal fluid.

Some wobblers treated with nutritional and medical management have shown improvement, but the results are not impressive. If the cause is compression of the spinal cord a veterinary surgeon, with the proper training and experience, can decompress the spinal cord and fuse the problem vertebrae, usually by using Titanium baskets and bone marrow transplants. This is similar to the recent surgery done to the professional football quarterback Peyton Manning. It ain’t cheap folks!

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The intervertebral discs are structures located between the bodies of the vertebrae and act as shock absorbers. They are composed of a rim of tough, fibrous connective tissue covering surrounding a gel-like center. A Hansen Type I rupture occurs when the fibrous capsule breaks, allowing the inner nucleus to push out through the opening and impinge on the spinal cord or a nerve root. A Hansen Type II occurs when the entire disc, surrounded by an unbroken capsule, impinges on nerve tissue.

Hansen Type I ruptures usually occur in small breeds such as Dachshunds, Beagles, Cocker Spaniels, Pekingese, and small mixed breeds. Ruptured discs are more common in Dachshunds than in all other breeds combined. The capsule can start to degenerate when the dog is only 2 to 9 months of age. Nearly eighty percent of Type 1 ruptured discs occur in the lower back between the last thoracic and the first two lumbar vertebrae. The history often includes jumping off a sofa or stairs, but any abrupt movement can be sufficient to cause a Type 1 rupture. It is also possible for more than one disc to rupture.

The symptoms of a Type I rupture usually progress gradually but can appear suddenly. The dog holds her/his back stiffly and may vocalize with pain or snap at the hand palpating in or around the injured area. The dog will usually refuse to walk up stairs or jump into a car. Neurological signs include weakness, lameness, and a wobbly gait. A dog experiencing severe back pain resulting from an acute rupture usually assumes a hunched-up position with a tight abdomen and may pant and tremble. Sudden ruptures can result in complete hindlimb paralysis.

Dogs with a Hansen Type I rupture in the neck usually carry their head low and stiff and are in extreme pain. The dog will often cry out when patted on the head and refuse to lower her head to eat or drink. There may be weakness and/or lameness of the front legs. Complete paralysis of all four limbs can occur but is rare.

Hansen Type II disc ruptures occur most in German Shepherds, Labrador Retrievers and other larger breeds. With this condition the entire disc, surrounded by its capsule, gradually impinges on the spinal canal. Symptoms usually appear gradually and progress slowly in dogs 5 to 12 years of age.

Your veterinarian can presumptively diagnose a ruptured disc by doing a neurological examination and prove it with imaging studies including spine X-rays, a myelogram, and possibly a CT scan or MRI.

Dogs still able to walk but with pain and mild weakness can be treated by confining them to a cage for a minimum of two weeks with appropriate anti-inflammatory drugs and drugs for pain control. If there is no improvement, or the dog’s condition worsens during this time, surgery is necessary. Surgery for disc disease involves surgical decompression of the spine by removal of bone over the spinal cord a laminectomy or partial bone removal (hemilaminectomy) and removal of the extruded disk material impinging on the spinal cord thus relieving the compression of the cord. Obviously, a very well trained and experienced veterinary surgeon is necessary for these procedures.

The prognosis for these cases depends upon the degree of injury and the location. Most patients that retain motor function have a good chance for recovery. If motor function is compromised the prognosis is more guarded and if deep pain perception is absent, a return to normal is less likely. We have all seen those photos of paralyzed dogs suspended in a two-wheeled cart who suffered this condition and still function as loved pets.

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