Cervical Vertebral Malformation-Malarticulation Syndrome in the Bernese Mountain Dog: Clinical and Magnetic Resonance Imaging Features
J.S. Eagleson1; J. Diaz2; S.R. Platt1; M. Kent1; F. Gruenenfelder1; N.J. Sharp2; S.J. Schatzberg1
The Bernese mountain dog (BMD) has been described sporadically in the literature as a breed affected by cervical vertebral malformation-malarticulation (CVMM) syndrome. However, the clinical and imaging features of CVVM in BMDs have not been characterized. The purpose of this retrospective report was to describe the clinical presentations and the MR imaging characteristics in a small, unrelated group of BMDs with CVMM.
Seven BMDs (four males, three females) diagnosed with cervical myelopathy were evaluated using MR imaging at two referral hospitals (2003-2007). Age ranged from eighteen months to seven years (median=5.2 years); weight ranged from 40.0 kg to 57.3 kg (mean=50.1 kg). Four dogs had a neuroanatomic localization of C1-C5. Of the four dogs, three presented with upper motor neuron paresis and general proprioceptive ataxia in all four limbs, and one dog presented with paraparesis and pelvic limb proprioceptive ataxia. All four dogs with C1-C5 localizations were ambulatory. Three dogs had a C6-T2 neuroanatomic localization, two of which were ambulatory but tetraparetic with general proprioceptive ataxia in the pelvic limbs; the other dog was severely tetraparetic and non-ambulatory. Three of seven dogs were neck guarding at the time of evaluation. All dogs had progressive clinical signs ranging in duration from 3 days to 3 months.
Spin echo T1-weighted (T1W) and T2-weighted (T2W) images were obtained using a 1.5 Tesla magnet in 6 dogs and using a 1.0 Tesla magnet in 1 dog. All dogs had evidence of intervertebral disc degeneration, ventral extradural spinal cord compression associated with intervertebral disc protrusion +/- dorsal longitudinal ligament hypertrophy, dorsolateral extradural spinal cord compression associated with articular process hypertrophy (bilateral in 5 dogs and unilateral in 2 dogs), and some degree of intramedullary hyperintensity on T2W images at the level of spinal cord compression. All dogs had more than one compressive site (ventral or dorsolateral or both) within the region of C3-4 to C6-7. Dorsolateral compression was more significant than ventral compression in 6 of the 7 dogs.
In conclusion, CVMM in the BMD has features similar to CVMM in both the Doberman Pinscher and the Great Dane.