Severity of spinal cord dysfunction and pain associated with hydrated nucleus pulposus extrusion in dogs.

OBJECTIVE To identify the severity of neurological deficits, presence of signs of cervical pain, and the site of intervertebral disc space extrusion in 21 dogs diagnosed via magnetic resonance imaging (MRI) with a hydrated nucleus pulposus extrusion (HNPE) and compare those findings to dogs with other compressive cervical myelopathies. METHODS Medical records and MRI findings were reviewed in dogs that were presented to two veterinary hospitals between 2006 and 2012 and subsequently diagnosed by MRI to have a HNPE (n = 21) or other compressive cervical myelopathies originating from the intervertebral disc (n = 174). Information obtained included signalment, severity of neurological deficits, presence of signs of neck pain, and site of HNPE. The severity of clinical neurological spinal cord dysfunction was determined for each dog in both groups using the Frankel scoring system (0-4). The MRI were reviewed for confirmation of diagnosis and site of HNPE. An ANOVA was used to compare age between groups and a Mann-Whitney test for pairwise comparisons of the Frankel score between groups. Values of p <0.05 were considered statistically significant. RESULTS Significantly more severe Frankel scores and less severe signs of cervical pain detected on palpation were observed in dogs with a HNPE as compared to dogs with other compressive myelopathies. The sites of HNPE were C3-C4 (8/21), C4-C5 (12/21), and C5-C6 (1/21). CLINICAL SIGNIFICANCE Dogs affected with HNPE have more severe clinical neurological deficits and less severe signs of cervical pain as compared to dogs with other compressive cervical myelopathies.