Let’s Discuss Discs.

The intervertebral disc is so small, yet it plays such a large part in our anatomy. The disc has multiple purposes, such as shock absorption and cushioning, and is an integral part of the spine. Without the disc, we would not be able to function. Each step we take is made possible because of our discs. The same can be said for our furry friends. Whether large or small, the intervertebral discs are imperative to daily living.

What Studies Say

According to multiple studies, the human disc and those of our furry friends are near exact in composition, and thus why studies can be done interspecies with high reliability.^1,2 Where the two differ in disc anatomy is the structure and size. Due to the difference in weight bearing, the animal spine does not require the amount of cushion the human spine does. Because we are two-legged and we walk upright, the main force on the spine is compressive. Our four-legged friends, however, experience mostly shearing forces. The loads they experience can be quite similar, the dispersion, however, varies between species.

The intervertebral disc is nearly 80% water, with the rest being collagen and proteoglycans.³ The centralmost part is by far the most pliable, being mostly water and proteoglycans.⁴ The further out we travel, the more fibrous and tough the material, mainly to maintain the structure of the disc under increased load bearing. As we age, the body requires an increased amount of water to stay hydrated. If you’ve ever seen an elderly person “shrink” over the years, it’s most likely due to dehydrated discs and the resulting bony fusion. To maintain the pillow like formation of the disc, it’s imperative to intake the proper amount of water daily. When a being becomes dehydrated, one of the first structures to suffer is the disc. Over time this dehydration becomes more permanent, the fibers toughen, and the disc is unable to rehydrate to it’s previous capacity. The areas where the nerves are exiting the spine become narrowed, thus increasing the likelihood of nerve impingement. Impact on the spine due to external loads is also heightened due to decreased cushioning.

When loads become abnormal due to structural shifting within the body, the discs will attempt to compensate by altering their own structure. Depending on where forces are most prevalent, the disc will move the majority of its fluid to the front, the back, or the sides, when in reality it should be fairly equal throughout with just a touch more cushion in the middle. If the structural shift is not addressed, eventually the discs can deteriorate and break down to where they begin to put pressure on the spinal cord. This is called a disc bulge. A disc bulge is maintained within the disc wall, and though it can put quite a bit of pressure on the posterior elements of the spine, it doesn’t break through the walls. A disc herniation, on the other hand, actually involves part of the disc breaking off and traveling away from the disc.

How Would One Recognize A Disc Bulge?

Well here’s the crazy part. There are probably a very large number of animals dealing with disc bulges due to structural shifting in the body. Within that large number, several will be asymptomatic at first and only begin showing symptoms late in life. Of those that are asymptomatic, a slight few will remain asymptomatic throughout their entire lives. Symptoms can vary within species and are sometimes unique to the animal itself. Disc bulges are diagnosed using MRI, though an educated guess is often made when certain symptoms are present. The treatment plans for a disc bulge are pretty standard whether diagnosed or not.

Some choose to do nothing, mainly because they do not realize the severity of the condition or what it implies. The next option is to treat with surgery, a touch more invasive but also effective at removing the bulge and relieving pressure on the spinal cord and nerves. If the bulge is being caused by a structural shift in the spine as it often is, however, surgery will act as a bandaid for some time until similar problems arise in either the same area or different ones. The body will always compensate for areas of weakness, and unfortunately these compensations can lead to worse problems.

Another option is to use medication to manage pain and other symptoms. This option is also effective with regards to pain relief, however, is in the same boat as surgery. Until the structure is stabilized, the problem will persist. Lastly, the bulge can be managed with alternative therapies, such as chiropractic care. Chiropractic care addresses those structural shifts in the body, thus helping relieve secondary conditions such as the disc bulge. Through adjustments, mobility is restored and stability can be achieved in the spine. When this occurs, the disc will naturally rehydrate and reabsorb into the proper position thus relieving pressure on both the nerves and cord.

What Are The Symptoms?

Though they vary depending on disc bulge location, symptoms tend to be fairly standard.

• limping
• back or neck pain
• changes in gait
• inability to go up and down stairs
• sensitivity to touch
• heat radiating from spine
• biting or itching certain areas of the spine
• constantly looking backward at a spot on their back
• partial paresis
• bowel or bladder changes
• unwillingness to walk or run
• inability to get comfortable
• pacing

Disc problems can take a great deal of time to heal, both conventionally and non-conventionally. The best way to avoid having a disc problem is prevention. Maintaining the proper structure of the spine, in addition to having proper hydration and nutrition is the best way to help prevent disc problems. Structural shifts are a result of daily life, they are simply going to happen. Sleep well knowing that there are ways to correct these shifts and maintain proper structure in the body!

Sources:

1. Showalter BL, Beckstein JC, Martin JT, Beattie EE, Espinoza Orías AA, Schaer TP, Vresilovic EJ, Elliott DM. Comparison of animal discs used in disc research to human lumbar disc: torsion mechanics and collagen content. Spine (Phila Pa 1976). 2012 Jul 1;37(15):E900-7.
2. Beckstein JC, Sen S, Schaer TP, Vresilovic EJ, Elliott DM. Comparison of animal discs used in disc research to human lumbar disc: axial compression mechanics and glycosaminoglycan content. Spine (Phila Pa 1976). 2008 Mar 15;33(6):E166-73.
3. Marchand F, et al. (1990) “Investigation of the laminate structure of lumbar disc anulus fibrosus.” Spine – 1990; 15:402-410.
4. Ullrich, Peter Jr. http://www.spine-health.com/conditions/spine-anatomy/spinal-discs.

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