Back Pain

Any and all of the symptoms are generally the result of pain.  As many of us know, back pain can be excruciating.  As such, it is easy to understand how are pets by react to it in these various ways.

What causes back pain?

When we're talking about back pain, generally we're speaking about pain related to the spinal cord.  In particular, pain is generated when there is some form of compression or inflammation involving the spinal cord or the nerve roots that come out of the cord. In order to understand this, it helps to know how the spine and spinal cord relate to one another.  The spine is made up of the series of bones called vertebra.  Each vertebra is separated from the next by and intervertebral disc.  The intervertebral disc has a firm fibrous outer coating surrounding a semi soft center.  This structure allows the disc to be flexible, which in turn allows the spine to flex and bend.  The vertebra create a canal in which lies the spinal cord.  The bony canal protect the delicate spinal cord from injury.  At the junction of to vertebra, a whole is formed called the intervertebral foramen.  It is through this foramen that the spinal nerves exit the spinal canal and innervate the body. 

The spinal cord living inside of the vertebral canal can be compared to a foot inside of the shoe.  The shoe protects the foot as the vertebral canal protects the spine.  Like the foot in the shoe, the spinal cord has a small amount of space around it.  If one should get a pebble in the shoe, the foot becomes painful very quickly because the shoe does not allow the pebble to move away from the foot.  In a similar fashion, if material should enter the spinal canal and press on the spinal cord it can become readily inflamed because it has nowhere to move due to the hard nature of the spinal canal.  Therefore, anything that enters the spinal canal may cause compression of the spinal cord which may lead to pain and ultimately to loss of function.

The most common cause of spinal compression is rupture of the intervertebral disc and subsequent movement of disc material into the spinal canal which compresses the spinal cord.  Intervertebral disc collapse can be partial or complete.  Intervertebral discs can rupture either suddenly or slowly and progressively.  Rapid ruptures tend to cause  rapid onset of symptoms and tend to do more damage to spinal cord.  Progressive disc rupture may be caused by gradual deterioration of the disc and may result in slowly worsening and/or intermittent symptoms.

Other causes of spinal pain include tumors growing inside of the spinal cord, tumors growing inside of the spinal canal but outside of the spinal cord, tumors of the vertebral bones and infection in the spinal cord or surrounding bone.

How we diagnose intervertebral disc disease?

Diagnosis of back pain begins with a thorough history from the owners and physical exam.  Frequently, the history will close the doctor and to the possibility of back or neck pain.  During the physical examination, pain will usually be elicited as the doctor palpates the different areas of the spine.  The neurological examination may reveal reduced function in one or both hind limbs as a result of spinal compression.  Diagnostic radiographs (x-rays) are used to determine the location and severity of the disease process.  Standard radiographs may show narrowing of the space between the vertebra as evidence of collapse disc, or there may be other lesions associated with the bones revealing infection or cancer.  In some cases, the standard radiographs may look normal, however the clinical symptoms may tell us that there is indeed a collapse disc in the back.  Generally is necessary to sedate or anesthetize the patient in order to get in appropriate diagnostic films.  Usually we will check a blood panel and urinalysis to look for other sources of disease which may be causing the pain.  In some cases, we will perform magnetic resonance imaging (MRI) or a myelogram to get detailed information about the status of the spinal cord, the location of the lesion and to help differentiate what type of lesion we're dealing with.

How we treat back pain?

The treatment of back pain depends on the cause of the problem.  In the case of infection, treatment includes long-term antibiotics, anti-inflammatory drugs and rest.  In the case of tumors, surgery, chemotherapy or radiation therapy may be able to treat the problem. In the case of intervertebral to disc collapse, we use a combination of steroid drugs, muscle relaxants, and pain control medication along with strict rest to help resolve the painful crisis.  If a pet has lost function in the back legs, then we may have to consider surgery to decompress the spinal cord and remove the rupture disc material.

What is the prognosis for spinal pain?

The prognosis for back pain varies with its cause.  Any pet that has experienced back pain, has the potential to have recurrence of the problem throughout its life.  If the only symptoms that the pet is experiencing is pain, and there is no loss of function at the time of diagnosis, the prognosis is generally good.  Most of these pets will recover from the pain and go on to live normal lives.  There is a high probability that at some point in their lives, these pets will have recurrence of the problem.  When and if that occurs, there is no predicting how severe it will be. 

 Pets that have lost function in their back legs (can't move the legs voluntarily) have a very guarded prognosis from the beginning.  If there is loss of function, and medical management does not improve it within 24 hours, then decompressive surgery is the best therapeutic option available. Even with surgery, there is no guarantee that the spinal function will return. 

Infections of the spine or spinal canal are very variable in their outcome.  Generally, prolonged therapy is needed and even then, no guarantee can be made.

Cancer of the spine always carries a guarded prognosis. Chemotherapy, radiation and surgery offer improved survival for these pets. 

While this does not sound like there is a great prognosis for this problem, many pets are successfully treated for these various syndromes and one should not give up hope prematurely.