[The nerve root syndrome in small animals - A review focussing on pathophysiology and therapy in the dog].

A large variety of etiologies is considered to be the cause of nerve root syndrome in dogs. Lateralized disc herniation, foraminal stenosis and malignant as well as benign nerve sheath tumors are some of the most important triggers described. The clinical signs of a nerve root syndrome are characterized by monoparesis in combination with progressive lameness, which may be accompanied by an elevation of the affected limb. Although the problem is well known among clinicians, there is no review article in the veterinary literature that specifically covers the subject of "nerve root syndrome in small animals". Mostly, this is merely mentioned as a symptom of its potential etiologies, as the so-called "nerve root sign" or "nerve root signature". In the pathophysiology of nerve root compression or irritation, a number of biomechanical and biochemical factors play a role. These occur individually or in combination and may lead to the same changes. The pathophysiology of the syndrome seems to focus around changes in microcirculation. These microcirculation disorders not only lead to pathomorphological changes such as edema formation, demyelination and axon death, but also initiate a cascade of reactions at the site of damage as well as in the central nervous tissue. This leads to the release of various neuropeptides, modulation of nerve excitability and impulse transmission. Different pathomechanisms therefore often lead to a uniform damage pattern, which makes it difficult to point out the original triggering factors. The body's response to these factors determines whether a nerve root syndrome actually develops or not. The treatment of the cause, if found, and an individual and multimodal pain therapy seem to be the most successful therapeutic approaches for nerve root syndrome in dogs.