The Ins and Outs of Spondylosis and Discospondylitis

As humans age, we often develop spinal problems that are painful, and debilitating. That’s one thing we share, unfortunately, with pets. Dogs and occasionally cats get similar spinal problems, including spondylosis and the more serious discospondylitis. Because they’re not always painful, you’ll need a doctor’s help to detect and distinguish them.

What Happens in Spondylosis?

The spinal column consists of a stack of bones known as vertebrae. At the top of this stack, the spinal cord is encased in a canal that runs the length of the body. Under the spinal canal sit the main part of the vertebrae, the bodies, which in healthy spines are clearly separated by intervertebral discs. These discs provide stability and flexibility for movement.

In spondylosis deformans, a bony bridge develops between the vertebral bodies, underneath the vertebrae or on the sides. Bony spurs called osteophytes appear, sometimes in one place but often in many. They may occur anywhere along the spine but are more common in the midback (thoracic and lumbar).

This commonly happens with aging. Vets don’t completely understand the cause but think it may be the body’s attempt to decrease mobility between vertebrae once they have lost their stability. Loss of stability may be a consequence of weakened intervertebral discs.

Treating Spondylosis

Spondylosis is often identified during X-rays, whether in normal dogs or dogs with back pain. It rarely causes symptoms in animals; However, you may notice stiffness, reduced flexibility or sensitivity to touch, if the spur grows near a nerve root coming out of the spinal canal.

While the bridging can look dramatic on X-Rays, spurs usually don’t touch the spinal cord or nerve roots and often don’t cause pain. Spondylosis may actually be beneficial in some cases, fusing two vertebrae and making intervertebral disc herniations less likely.

When spondylosis appears along four adjacent vertebrae, it’s called Diffuse Idiopathic Skeletal Hyperostosis (DISH). Boxers and some kinds of cats seem prone to it. Like standard spondylosis, DISH rarely causes symptoms but can cause pain. Treatment with anti-inflammatory drugs can be effective. Physical therapy, weight loss and controlled exercise programs may also help.

In the rare event that an osteophyte causes spinal cord compression, as it can in humans, a surgeon might remove it. But if there’s no pain, your pet doesn’t need further treatment.

Discospondylitis: A More Serious Matter

Discospondylitis has different causes and consequences. The letters “itis” at the end of a medical word indicate inflammation, as in arthritis (inflammation of the joints) or gingivitis (inflammation of the gums). Discospondylitis is an infection of the vertebral bodies and intervertebral discs.

It’s often caused by bacteria or fungus that took hold elsewhere in the body and found a favorable environment to live in the spine. The most common cause is bacteria that originate from a urinary tract infection and get into the bloodstream (hematogenous spread). Pathogens can also the body through migrating plant material like grass awns or foxtails that are inhaled.

This condition brings extreme pain to the back or neck and can cause weakness or incoordination. If untreated, bones can become so weak that they break, ultimately causing paralysis.

How Vets Treat Discospondylitis

Discospondylitis can be identified in most cases by an X-ray of the spine. The bones will be less distinct and are often described as “fuzzy or motheaten”. Occasionally X-rays are not sensitive enough and a CT scan or MRI is required for a diagnosis. Routine bloodwork can show signs of systemic inflammation but is often normal. To determine the cause of the discospondylitis, cultures of the blood and urine may be helpful. Optimal antibiotics may be based on these cultures and should have preferred bone penetration. Dogs may need to take this medication for many months (even up to a year!) to prevent a recurrence of the infection.

During that time, you and your veterinarian must monitor progress, starting with check-up X-rays about six to eight weeks after starting antibiotics. Bones heal slowly, and in some cases, a dog may need six to 12 months to recover fully.

See more details in the slide presentation below.

As you see, X-rays are the first-line tool to catch benign spondylosis, more dangerous discospondylitis and other conditions. However, X-rays see only bones and often cannot identify other spinal conditions. For that reason, veterinary neurologists may use MRIs to study the spinal cord and nerves in greater detail.

Charlotte Animal Referral and Emergency is the animal version of a human medical center. CARE offers every type of treatment for pets, from emergency care 24 hours a day, 365 days a year, to board-certified specialty care after a referral from your primary veterinarian. You can take a visual tour of the practice at carecharlotte.com/tour.