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Summary
Spondylosis deformans (or "spondylosis," as most veterinarians refer to it) is a chronic disease process of the spine where bone spurs (osteophytes) form at the edges of the vertebrae. Sometimes, these may even coalesce into bony bridges between the vertebral segments of the spine.
While the lower back is most often affected (the lumbar vertebral bodies), the thoracic vertebra, especially those closest to the lumbar spine, are often involved as well.
The cause of this common canine disease is unknown, but intervertebral disc disease ("slipped discs"), trauma to the spine, autoimmune diseases and congenital deformities have all been associated with similar lesions we veterinarians may also refer to as spondylosis. Nonetheless, true spondylosis deformans patients suffer an "idiopathic" form, meaning that the cause is not identifiable.
Middle-aged to older animals and bigger-breed dogs are predisposed. Though dogs are more likely candidates for this condition, cats can suffer, too.
Symptoms and Identification
In most cases the disease sounds more painful than it actually is. In fact, most dogs and cats who suffer spondylosis deformans are asymptomatic, meaning that they appear to suffer no symptoms. (In animal medicine, however, it's important to note that our human perception of pain may inadequately represent the true state of our patients' feelings.)
In pets who do show signs, these are usually correlated with larger size, larger lesions and older age. In these cases, the spine or nerve roots may be compressed by the bigger bone spurs. Lameness (limping), back pain, stiffness and loss of muscle mass over the affected areas are the most common symptoms.
In any case, spondylosis deformans is almost always diagnosed with X-rays, though CT (computed tomography) and MRI (magnetic resonance imaging) will also reveal the lesions. A CT scan and/or myelogram (a dye-based study of the spinal canal) are often used to diagnose spinal cord compression if it's suspected.
After finding the telltale bone spurs, care must be taken to rule out previous trauma, disc disease and other spinal diseases before assuming that spondylosis deformans is their underlying cause. These possibilities may necessitate further tests such as a cerebro-spinal fluid (CSF) tap and advanced lab tests, though they're usually not undertaken if no symptoms are in evidence.
Affected Breeds
Some studies suggest that Boxers are the most common breed affected, with other larger breed dogs (such as German shepherds and Airedale Terriers). Nonetheless, this area of study is not without its controversy. Veterinary radiologists posit that smaller breeds, such as Cocker Spaniels and Dachshunds may be as likely to suffer. Unfortunately their small size and proportionally smaller lesions mean that theirs are more likely to go undetected, thus obscuring the true incidence among the breeds.
Treatment
The treatment of spondylosis deformans depends almost exclusively on the degree of back pain, lameness, stiffness or loss of muscle mass the patient experiences. Pet-specific anti-inflammatory medication is the typical approach (either NSAIDs or corticosteroids), though some pets (particularly larger dogs) may require additional drugs such as opiates (like tramadol).
Some severe cases, however, may require surgery to relieve the pressure on the spinal cord caused by the bone spurs. Though rare, it's a consideration to keep in mind should your pet be diagnosed with spondylosis deformans and suffer from larger lesions.
All affected pets may also benefit from the use of nutraceuticals (like glucosamine) or polysulfated glycosaminoglycans (Adequan). These products appear to be helpful to the cartilage between the joints and may well improve function and decrease pain.
Veterinary Cost
Because most pets suffer no symptoms, expense is not a significant consideration for the average spondylosis deformans patient. Even with mild to moderate pain, the disease is reasonably inexpensive to manage with medications and nutraceuticals ($20 to $100 a month, depending on the pet's size and pain relief requirements).
For surgical candidates, however, the expense is considerable. $3,000 to $5,000 is fairly typical for the diagnostics and surgery afforded these patients.
Prevention
Genetic predisposition to this disease is likely, though this certainly--much less its mechanism-- has not been established. Modes of prevention, therefore, are speculative, and center around removing severely affected animals and their offspring from the genetic pool (though this is of questionable efficacy at this point and therefore especially difficult to accomplish).
References
1. Morgan JP. Spondylosis deformans in the dog. Acta Orthop Scand Suppl 1967;96:7-88.
2. Morgan JP, Ljunggren G, Read R. Spondylosis deformans (vertebral osteophytosis) in the dog. A radiographic study from England, Sweden and U.S.A. J Small Anim Pract 1967;8:57-66. [Medline]
3. Read RM, Smith RN. A comparison of spondylosis deformans in the English and Swedish cat and in the English dog. J Small Anim Pract 1968;9:159-166. [Medline]
4. Breit S, Kunzel W. The position and shape of osteophyte formations at canine vertebral endplates and its influence on radiographic diagnosis. Anat Histol Embryol 2001;30:179-184. [CrossRef] [Medline]
5. Langeland M, Lingaas F. Spondylosis deformans in the Boxer: estimates of heritability. J Small Anim Pract 1995;36:166-169. [CrossRef] [Medline]