It might start with something as simple as noticing that your dog has slowed down. Or when you pick him up, he yelps with pain. Maybe his back legs are weak, and he's pulling himself more with his front legs. These can all be signs of spinal cord compression, which, left untreated, can progress to debilitating pain and even paralysis. Luckily, it can, in most cases, be treated surgically.
Spinal cord problems and disorders occur quite frequently in pets and not only in dachshunds and pekingese. The spinal cord is a direct extension of the brain. It travels down through the vertebra, which makes up the backbone all the way to the beginning of the tail. Between each vertebra there is a disc - a cushioning device attached to the end of each vertebra that absorbs shock and allows mobility and flexibility to the spine (See Figure 1). The disc is donut-like in appearance and consists of a strong fibrous outer ring with a less dense, almost gelatinous center to it. Spinal nerves leave the cord itself and extend out to provide feeling and motor control to body parts. Usually, these nerves exit between the vertebra, so the cord, and the nerves, are intimately associated with the disc itself.
By far the most common spinal problem is when inner disc material moves out of place and puts pressure on the cord (see Figure 2). When compressed in that bony tunnel, it quickly becomes seriously traumatized. From the point of compression, spinal cord function forward toward the head is generally maintained, but all motor, sensory and voluntary control from the compression point back toward the tail can be compromised. If the disc compression is in the neck, then all four legs are affected.
Symptoms can develop suddenly or slowly and can range from just weakness (dragging toes, etc.) all the way to complete, irreversible paralysis. Any evidence that back or neck pain may be causing hind leg weakness or an inability to stand should be considered an emergency.
Fortunately, skilled and experienced veterinary care can usually stabilize and correct the problem. The most serious condition, when time is the most critical, is the sudden onset of paralysis. If the cord is severely injured - meaning no transmission of pain sensation exists - we have at most 6 hours to surgically get to that cord and relieve the pressure. Even then, surgery is not always successful.
When pain sensation exists from the hind legs to the brain, but there is no motor control, surgery is the most likely approach for success. Should pain sensation exist and partial muscle tone remain so that the pet can support some weight, surgery will still enhance and speed recovery.
The surgical approach must be based on the identification of a very precise location of compression, and identifying the site of compression can be challenging. As the cord itself is buried in a tunnel of bone, plain x-rays are rarely of use. Advanced imaging is necessary such as:
- Myelography: a dye is introduced into the spinal fluid that surrounds the cord. This appears white on x-ray images and will specifically identify the spinal cord most of the time, including the site of compression.
- CT Scans: CT Scans are less invasive, quickly obtained and generally much more accurate as the images demonstrate all tissue structures in cross section.
- MRI: MRI is excellent, and possible, but logistically more difficult and can take up to an hour or more of anesthesia and the fact is, it is usually unnecessary.
Having performed hundreds of myleograms over many years, I now rely on CT much more. Once imaging confirms the presumed diagnosis of disc compression, then treatment becomes the next concern.
Surgery requires a great deal of skill, experience and patience to provide the highest percentage of successful return to normal function. The muscles are separated from the bony vertebra, and removal of bone of the vertebra on each side of the defined disc space then exposes the spinal cord. The disc material is trimmed away to eliminate the compression, allowing the spinal cord to return to its normal shape.
The immediate post-surgical hospital care can be as critical as the surgery itself. Urine and bowel movement control, appetite, etc., all pose challenges that must be dealt with. Overall, when the criteria I have mentioned are met and in the hands of an experienced team, a successful return to normal function can be anticipated in most cases.
I must also stress that proper post-operative care and treatment, which includes dedicated family care and physical therapy, greatly improves the chances of a successful recovery.
If you think your pet may be exhibiting any of the symptoms described, do not hesitate to give us a call or make an appointment. Remember, if your pet is experiencing any decline in neurological activity, TIME IS EVERYTHING!