Before we dive into our discussion about intervertebral disc disease (IVDD for short), let’s do a quick review on the anatomy of the canine and feline back. The spinal column is composed of the spinal cord surrounded by its protective big brother: the vertebral column (the bones of the back). In the cat and dog, the spinal column is divided into five regions, from head to tail: the cervical vertebrae, the thoracic vertebrae, the lumbar vertebrae, the sacral vertebrae and the caudal vertebrae.
The vertebral column consists of multiple vertebrae with intervertebral discs lying between. These discs serve as a cushion between the vertebrae, so that the back can move and bend while still protecting the very important and very sensitive spinal cord. The intervertebral discs consist of a fibrous tissue outer layer and a soft inner core (the analogy of a jelly filled donut is often used to describe the structure of the intervertebral discs).
IVDD is a disease process that involves the soft inner core of the intervertebral disc becoming dry and brittle and pushing up on the top layer of the fibrous tissue outer layer. The soft inner core can either protrude into, or even rupture through the fibrous tissue outer layer. This results in pressure to and damage of the spinal cord and subsequent clinical signs of IVDD.
The clinical signs of IVDD can vary depending on where along the spinal column the IVDD has occurred (and yes, it can happen in more than one area at a time) and how severe the impingement is on the spinal cord. The regions most affected are the thoracic and lumbar, but cervical IVDD is also quite common.
The clinical signs of IVDD include any combination of the following, and may be vague or intermittent at times:
- Acute back pain
- Stiff/guarded gait
- Reluctance to move/jump
- Arched back
- Muscle spasms of the back muscles
- Weakness or wobbly when walking
- Crossing of the limbs when walking or knuckling over of the feet
- Paresis (slight or incomplete paralysis)
- Paralysis (loss of motor function)
- Loss of deep pain perception
As with most diseases, there are breeds that are more commonly affected, but this is a condition that can affect any and all breeds. The condition can be seen in cats as well, but it is more common in dogs.
Tomorrow, we’ll talk about diagnosing IVDD and options for treating a pet suffering from the condition.
To more waggin’ and purrin’. rwkj