[The intervertebral vacuum phenomenon as a computed-tomographic finding in the dog and its significance as an indicator for surgical treatment of vertebral disc herniations].

OBJECTIVE

The intervertebral vacuum phenomenon (VP) in the dog describes an accumulation of gas in the intervertebral disc space. It occurs primarily after vaporization of solute gases in the extracellular fluids in fissures of degenerative vertebral discs but can also arise following a sudden fall in pressure, for example, after a vertebral disc herniation. VPs are detectable using radiography, computed tomography (CT) and magnetic resonance imaging (MRI). Intervertebral VP occurrence is an indication for vertebral disc herniation. The aim of this study was to determine the frequency and localization of the VP in intervertebral disc spaces of dogs and further to correlate the incidence of intervertebral VP with vertebral disc herniation indicative for surgical treatment.

MATERIAL AND METHODS

We evaluated CT-studies of the vertebral column of dogs presented at the clinic between January 2007 and June 2012 (n = 693). In total, 529 cases fulfilled the inclusion criterion of a CT-study of the vertebral column from the first thoracic vertebra to the first sacral vertebra in the soft tissue and bone windows. The evaluation included an inter-observer comparison between observers with and without practical experience.

RESULTS

Observers with and without practical experience identified intervertebral VP in 5.7% and 6.8% of the dogs, respectively, with a mean age of 7.7 ± 2.9 years and 7.3 ± 3.1 years, respectively. More male than female dogs were affected. In total, 66.7% and 63.9% of the dogs with VP, respectively, received surgical treatment of the vertebral column. The surgical site correlated with the location of the intervertebral VP in 55.0% and 65.2% of cases, respectively.

CONCLUSION AND CLINICAL RELEVANCE

Although intervertebral VP can indicate vertebral disc degeneration and herniation, it should not be considered a unique identifier. Localization for surgery should be based on clinical symptoms and CT- and/or MRI-findings showing vertebral disc herniation or compression of the spinal cord. Practical experience is unnecessary to detect an intervertebral VP.