Dorsal vertebral column abnormalities in dogs with disseminated idiopathic skeletal hyperostosis (DISH)

Although disseminated idiopathic skeletal hyperostosis (DISH) most often affects the ventral aspect of the vertebral column, this study evaluated the occurrence, nature and clinical relevance of dorsal vertebral column abnormalities in 10 dogs with DISH for which CT or MRI and a complete neurological examination were available. Dorsal vertebral column abnormalities were present in eight dogs and included articular process hypertrophy (n=7 dogs), periarticular new bone formation (n=1), pseudoarthrosis between spinous processes (n=4) and thickening of the dorsal lamina (n=4). These dorsal vertebral abnormalities caused clinically relevant vertebral canal stenosis in six dogs and were the only cause of clinical signs in four of these dogs. Although the lumbosacral joint was not affected by DISH, these six dogs demonstrated lumbosacral vertebral canal stenosis and clinical signs of cauda equina compression, which included paraparesis (n=5 dogs), lumbosacral pain (n=4), urinary incontinence (n=4), faecal incontinence (n=1) and urinary and faecal incontinence (n=1). There is a possible association between DISH and hypertrophy of dorsal vertebral structures, potentially resulting in vertebral canal stenosis. Although these changes occurred at segments fused by DISH, they predominantly affected adjacent non-affected segments.