A disc is a cushion of cartilage that sits between the vertebrae and acts as
a shock absorber. It is composed of a rim of tough, fibrous connective tissue
that surrounds a gel-like center called the nucleus. When a disc ruptures, one
of two things may happen. The first is that the fibrous capsule breaks,
allowing the inner nucleus to push out through the opening and impinge on the
spinal cord or a nerve root. This type of rupture is
called a Hansen Type 1. The second is that the entire disc, surrounded by an
unbroken capsule, can bulge outward. This is called a Hansen Type 2.
The diagnosis of ruptured disc is made by neurological examination and
imaging studies including spine X-rays, a myelogram, and possibly a CT scan or
Ruptured discs in the back of the Hansen Type 1 occur in small breeds such
as the Dachshund, Beagle, Cocker Spaniel, Pekingese, and small mixed breeds. In
fact, ruptured discs are more frequent in Dachshunds than in all other breeds
The capsule begins to degenerate at about 2 to 9 months of age, and signs of
impingement on the spinal cord appear at 3 to 6 years of age. About 80 percent
of Type 1 ruptured discs occur in the lower back between the last thoracic and
the first two lumbar vertebrae. Most of the remainder occur in the neck. There
is often a history of mild trauma, such as jumping off a sofa, but normal
movements are sufficient to cause a Type 1 rupture. Occasionally, more than one
disc becomes ruptured.
The symptoms of a Type 1 rupture usually come on gradually but can appear
with sudden explosiveness. The main sign is pain. The dog holds her back stiffly
and may cry or whine when patted or handled in the injured area. She usually
refuses to walk up stairs or jump into a car. Neurological signs include
weakness, lameness, and a wobbly gait. A dog experiencing the severe back pain
of an acute rupture will have a hunched-up position and a tight abdomen. The
dog may pant and tremble. Sudden disc ruptures can produce complete hindquarter
Hansen Type 2 discs ruptures occur in the larger breeds, including German
Shepherd Dogs and Labrador Retrievers. The entire disc, surrounded by its
capsule, gradually impinges on the spinal canal. Symptoms appear in dogs 5 to
12 years of age. Because the process is gradual, symptoms progress slowly.
Ruptured discs in the neck of the Hansen Type 1 cause a dog to carry her
head low and rigidly, making the neck look shorter. This type of injury is extremely
painful. A dog will often cry out when patted on the head and refuse to lower
her head to eat and drink. Weakness and lameness involve the front legs.
Complete paralysis of all four legs does occur but is rare.