Since that time, most publications have focused on descriptive and comparative studies involving multiple modalities, typically either CT or MRI, or both.Ī 2016 study looked at the practice patterns of diplomates of the American College of Veterinary Internal Medicine in the specialty of Neurology and American College of Veterinary Surgeons for the diagnosis of IVDH in North America. It was also in the 2000s that magnetic resonance imaging (MRI) and computed tomography (CT) started to become routinely used in referral hospitals. Starting in the 1990s, published case series began to have all dogs confirmed with myelography ( 17), which then became the norm in the publications from the 2000s onward ( 18). Myelography started to be used in the 1960s and 1970s ( 12, 13), but publications utilizing this technique in dogs remained variable until the early to mid 1990s ( 14– 16). Radiography was the most widely used method for the diagnosis of IVDD starting in the 1950s and extending until the 1980s ( 4, 9– 11). The most commonly described clinical form of intervertebral disc herniation (IVDH) is IVDE, which leads to acute spinal pain and variable degrees of paresis up to paralysis. A study with 677,000 dogs suggested that the overall prevalence of all intervertebral disc degeneration-related diseases was 27.8% ( 1). In addition, intervertebral disc (IVD) degeneration and protrusion are also associated with other important spinal conditions such as cervical spondylomyelopathy and degenerative lumbosacral stenosis ( 7, 8). Over the years and primarily with the widespread use of magnetic resonance imaging (MRI), newer forms began to be recognized, such as acute non-compressive nucleus pulposus extrusion (ANNPE), hydrated nucleus pulposus extrusion (HNPE) and intradural/intramedullary intervertebral disc extrusion (IIVDE) ( 5, 6). In 1952, Hansen classified IVDD into acute, or Hansen type I intervertebral disc extrusion (IVDE), and chronic, or Hansen type II intervertebral disc protrusion (IVDP) ( 4). The diagnosis of all IVDD forms is based on imaging, with the imaging techniques evolving over the years.Įven though IVDD was first reported in a paraplegic Dachshund by Dexler in 1896, it was truly well-characterized by Olsson and Hansen in the early 1950s ( 3). Intervertebral disc disease (IVDD) is the most common spinal cord disease of dogs, being responsible for 2.3–3.7% of admissions to veterinary hospitals ( 1, 2). The review focuses primarily on canine IVDH due to its frequency and vast literature as opposed to feline IVDH. The following review will provide a comprehensive overview on common imaging modalities reported to aid in the diagnosis of IVDH including IVDE, IVDP, ANNPE, HNPE, and IIVDE. Novel advanced imaging applications are being explored in dogs but are not yet routinely performed in clinical patients. Computed tomography with or without myelography and MRI is currently utilized most widely and have become the focus of most contemporary studies on this subject. Myelography addresses some of the constraints of survey radiographs but has largely been supplanted by cross-sectional imaging. While radiographs can provide useful information, especially for identifying intervertebral disc degeneration or calcification, there are notable limitations. Given how common IVDH is in dogs, a thorough understanding of the indications and limitations for each imaging modality to aid in diagnosis, treatment planning and prognosis is essential to successful case management. Many imaging techniques have been described in dogs with roles for survey radiographs, myelography, computed tomography (CT), and magnetic resonance imaging (MRI). These include intervertebral disc extrusion (IVDE), intervertebral disc protrusion (IVDP) and more recently recognized forms such as acute non-compressive nucleus pulposus extrusion (ANNPE), hydrated nucleus pulposus extrusion (HNPE), and intradural/intramedullary intervertebral disc extrusion (IIVDE). Imaging is integral in the diagnosis of canine intervertebral disc disease (IVDD) and in differentiating subtypes of intervertebral disc herniation (IVDH). 4Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hanover, Hanover, Germany. 3Department of Veterinary Clinical Sciences, Purdue University College of Veterinary Medicine, West Lafayette, IN, United States.2Department of Clinical Sciences and Services, Royal Veterinary College, London, United Kingdom.1Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH, United States.Lewis 3, Holger Volk 4 and the Canine Spinal Cord Injury Consortium (CANSORT-SCI) da Costa 1 *, Steven De Decker 2, Melissa J.
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