Comparison of high‐field MRI and multidetector CT for grading Chiari‐like malformation and syringomyelia in Cavalier King Charles Spaniels

Chiari‐like malformation (CM) and syringomyelia (SM) are common illnesses that can cause debilitating neuropathic pain in Cavalier King Charles spaniels (CKCS). The current imaging modality to screen CKCS for CM/SM is MRI of the brain and cervical spine. Magnetic resonance imaging provides good soft tissue detail and contrast of the cerebellum and cervical spinal cord. Computed tomography (CT) is another cross‐sectional imaging technique that facilitates brain and neck evaluation; however, soft tissue resolution does not match that of MRI. Computed tomography benefits include identification of concurrent craniocervical junction anomalies (atlantooccipital overlap) and shorter imaging/anesthesia times with the ability to use only sedation. The aim of this retrospective, method comparison study is to assess the utility of multidetector CT for screening CM and SM in CKCS as compared to high‐field MRI. Three groups of observers with different levels of experience graded CM and SM based on the British Veterinary Association/Kennel Club CM/SM classification criteria. Thirty CKCS underwent multidetector CT and 3 Tesla MRI studies. Computed tomography and MRI studies were reviewed at different timepoints to minimize bias. Computed tomography has lower Cohen's Kappa agreement for each observer group compared to MRI. The intraclass correlation coefficient averaging CM and SM for all groups was excellent using MRI, while CT was poor for SM and moderate for cerebellar herniation. Greater observer experience resulted in a higher agreement for CT and MRI. Magnetic resonance imaging should remain the standard for screening of CM and SM as CT can result in misclassification and greater disagreement.     

Association between the findings on magnetic resonance imaging screening for syringomyelia in asymptomatic Cavalier King Charles spaniels and observation of clinical signs consistent with syringomyelia in later life

A questionnaire-based study was used to investigate the association between the findings on magnetic resonance imaging (MRI) screening for syringomyelia (SM) in 79 asymptomatic Cavalier King Charles spaniels (CKCS) and the subsequent development of clinical signs consistent with SM in later life. Owners reported clinical signs consistent with SM in 13/79 (16%) dogs at the time of the questionnaire. A significantly greater proportion of CKCS with a syrinx visible on MRI screening showed clinical signs in later life (9/25, 36%) than dogs without a visible syrinx (4/54, 7%; odds ratio 6.9). Whether the findings of MRI screening can be used to indicate the likelihood of an asymptomatic CKCS developing clinical signs consistent with SM in later life warrants further prospective study in a larger cohort of dogs.     

Relationship of brain parenchyma within the caudal cranial fossa and ventricle size to syringomyelia in cavalier King Charles spaniels

Objectives : To assess if the volumes of the caudal cranial fossa (CCF), parenchyma within the caudal cranial fossa (CCFP) or ventricles (V) are associated with syringomyelia (SM) in cavalier King Charles spaniels (CKCS) with Chiari-like malformation (CM). To evaluate if volumes are associated with transverse syrinx width. Methods : Magnetic resonance images of 59 CKCS with CM were retrospectively reviewed and grouped with or without SM. Three-dimensional images were created and volumes of the fossae, brain parenchyma and ventricular system were calculated from which percentages of CCF, CCFP and V were created. If present, syrinx size was measured from its maximal transverse width. The percentages were statistically compared between groups, and correlation between percentages and syrinx dimensions was made. Results : CKCS with SM had significantly higher CCFP (P=0·0001) and V (P=0·0002) to those without but no significant difference in CCF (P=0·925). There was a positive correlation between CCFP and syrinx width (Pearson r=0·437) and ventricle size to syrinx width (Spearman r=0·627). Clinical Significance : A more marked overcrowding of the CCF is associated with SM, which may explain the high incidence of SM in CKCS with CM. The association between ventricle and syrinx dimensions supports the theory that SM development is the result of altered cerebrospinal fluid dynamics.     

Effectiveness of breeding guidelines for reducing the prevalence of syringomyelia

Several toy breed dogs are predisposed to syringomyelia (SM), a spinal cord disorder, characterised by fluid-filled cavitation. SM is a complex trait with a moderately high heritability. Selective breeding against SM is confounded by its complex inheritance, its late onset nature and high prevalence in some breeds. This study investigated the early outcome of existing SM breeding guidelines. Six hundred and forty-three dogs, 550 Cavalier King Charles spaniels (CKCS) and 93 Griffon Bruxellois (GB), were identified as having either one (454 dogs) or both parents (189 dogs) with MRI-determined SM status. Offspring without SM were more common when the parents were both clear of SM (SM-free; CKCS 70 per cent, GB 73 per cent). Conversely, offspring with SM were more likely when both parents had SM (SM-affected; CKCS 92 per cent, GB 100 per cent). A mating of one SM-free parent with an SM-affected parent was risky for SM affectedness with 77 per cent of CKCS and 46 per cent of GB offspring being SM-affected. It is recommended that all breeding dogs from breeds susceptible to SM be MRI screened; that the SM status at five years old is established; and all results submitted to a central database that can be used by dog breeders to better enable mate selection based on estimated breeding values.     

Chiari-like malformation with syringomyelia in the Cavalier King Charles spaniel: long-term outcome after surgical management

Objective– To evaluate long-term success of cranial cervical decompression for management of canine Chiari-like malformation with syringomyelia (CM/SM).
Study Design– Retrospective clinical study.
Animals– Cavalier King Charles spaniels (n=15).
Methods– After diagnosis by magnetic resonance imaging (MRI) dogs had cranial cervical decompression with durotomy. Seven dogs had the durotomy patched with biocompatible collagen matrix. Clinical outcome was monitored for >12 months.
Results– All dogs either improved (80%) or were unchanged (20%) postoperatively. Postoperative MRI in 6 dogs revealed persistence of syringomyelia. Seven dogs (47%) subsequently deteriorated, 0.2–2.3 years after surgery (mean, 1.3 years) and 2 dogs were eventually euthanatized as a consequence. Twelve dogs were still alive, 1–6.5 years after surgery (mean, 2.5 years).
Conclusion– Cranial cervical decompression surgery is associated with low mortality and morbidity, and results in clinical improvement in most dogs. The procedure seemingly does not result in syrinx collapse and resolution. Clinical improvement may not be sustained and some dogs can be expected to deteriorate.
Clinical Relevance– Cranial cervical decompression surgery may have a role in management of CM/SM. In dogs with severe pain, it can improve quality of life for several years; however, it does not appear to adequately address the primary cause of syringomyelia. Further prospective study is needed to better understand the pathogenesis and treatment of this disorder. Because this condition causes neuropathic pain but does not necessarily result in euthanasia more information is needed on appropriate pain management for these patients.     

Hydrocephalus and syringomyelia in a cat.

A 3-month-old male Japanese cat with feline parvovirus infection, showing central and cervical nerve abnormalities, was diagnosed as hydrocephalus and syringomyelia by use of magnetic resonance imaging (MRI). The cat was maintained clinically by medical treatment even though he could not stand. The MRI scans obtained about 5 months later showed that the ventricles had increased in size and the cervical syrinx had extended into the thoracic spinal cord. Ventriculoperitoneal (VP) shunt was performed. One week after surgery, neurological conditions had improved. At the postoperative MR images, the ventricles had decreased in size and the syrinx in the cervical and thoracic spinal cord could no longer be seen. The cat was still alive and was able to walk well.     

Evaluation of osseous‐associated cervical spondylomyelopathy in dogs using kinematic magnetic resonance imaging

Osseous‐associated cervical spondylomyelopathy in dogs is characterized by both static and dynamic spinal cord compression; however, standard MRI methods only assess static compression. In humans with cervical spondylotic myelopathy, kinematic MRI is commonly used to diagnose dynamic spinal cord compressions. The purpose of this prospective, analytical study was to evaluate kinematic MRI as a method for characterizing the dynamic component of osseous‐associated cervical spondylomyelopathy in dogs. We hypothesized that kinematic MRI would allow visualization of spinal cord compressions that were not identified with standard imaging. Twelve client‐owned dogs with osseous‐associated cervical spondylomyelopathy were enrolled. After standard MRI confirmed a diagnosis of osseous‐associated cervical spondylomyelopathy, a positioning device was used to perform additional MRI sequences with the cervical vertebral column flexed and extended. Morphologic and morphometric (spinal cord height, intervertebral disc width, spinal cord width, vertebral canal height, and spinal cord area) assessments were recorded for images acquired with neutral, flexion, and extension imaging. A total of 25 compressions were seen with neutral positioning, while extension identified 32 compressions. There was a significant association between extension positioning and presence of a compressive lesion at C4‐C5 (p = 0.02). Extension was also associated with a change in the most severe site of compression in four out of 12 (33%) dogs. None of the patients deteriorated neurologically after kinematic imaging. We concluded that kinematic MRI is a feasible method for evaluating dogs with osseous‐associated cervical spondylomyelopathy, and can reveal new compressions not seen with neutral positioning.     

Influence of head positioning on the assessment of Chiari-like malformation in Cavalier King Charles spaniels

Chiari-like malformation (CM) is almost omnipresent in the Cavalier King Charles spaniels (CKCS), often leading to syringomyelia (SM). Morphometric studies have produced variable results concerning relationship between the brain parenchyma within the caudal cranial fossa (CCF) and SM. The present study assesses the effect of head position, one potential confounder. Magnetic resonance images of CKCS with CM were reviewed in extended and flexed head positions. Volumes were calculated from transverse T2-weighted brain images. Mid-sagittal images were used for measurement of cerebellar herniation and CSF space between cerebellum and brainstem. Fourteen CKCS were included into the study, seven dogs with CM and seven with CM/SM. There was no difference between the relative brain parenchyma within the CCF in extended position and flexed position, or the brain parenchyma within the rostral and middle cranial fossae proportion. Cerebellar herniation and CSF space between cerebellum and brainstem were significantly increased in the flexed position. Cerebellar herniation and CSF space differed significantly between CM and CM/SM in a flexed head position. Volumetric measurements did not vary with head position. Cerebellar herniation and CSF space between the cerebellum and the brainstem were larger in a flexed head position.     

Syringomyelia in cavalier King Charles spaniels: the relationship between syrinx dimensions and pain

OBJECTIVES: This study was designed to test the hypothesis that pain associated with syringomyelia in dogs is dependent upon size and involvement of the dorsal part of the spinal cord. METHODS: Masked observers determined syrinx dimensions and precise location within the spinal cord on magnetic resonance images of 55 cavalier King Charles spaniels with syringomyelia. After removal of masking, syrinx size and location were compared between the cohorts of dogs that exhibited pain with those that did not. RESULTS: Maximum syrinx width was the strongest predictor of pain, scratching behaviour and scoliosis in dogs with syringomyelia. Both pain and syrinx size were positively correlated with syrinxes located in the dorsal half of the spinal cord. CLINICAL SIGNIFICANCE: Large syrinxes associated with damage to the dorsal part of the spinal cord are associated with persistent pain suggesting that the pain behaviour expressed by this group of patients is likely to be "neuropathic pain," resulting from disordered neural processing in the damaged dorsal horn. As such it is likely that conventional analgesic medication may be ineffective.     

Suboccipital craniectomy, dorsal laminectomy of C1, durotomy and dural graft placement as a treatment for syringohydromyelia with cerebellar tonsil herniation in Cavalier King Charles spaniels

OBJECTIVE: To evaluate retrospectively the efficacy of the suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft for treatment of syringohydromyelia (SHM) because of cerebellar tonsil herniation in Cavalier King Charles spaniels (CKCS). This technique is used with great success in human medicine. STUDY DESIGN: Four CKCS diagnosed by Magnetic resonance imaging (MRI) of SHM because of cerebellar tonsil herniation and not responsive to medical therapy underwent a suboccipital craniectomy and dorsal laminectomy of C1 (2 dogs) and of C1 and partial C2 (2 dogs) with durotomy and placement of a dural graft. Three dogs were evaluated neurologically 24 hours, 1 month, and 3 months postoperatively and evaluations were compared with preoperative neurological examination. Repeat MRI took place 3 months postoperatively. RESULTS: Neurological examinations showed neither improvement nor progression of clinical signs 3 months postoperatively. MRI showed no regression of syrinx size 3 months postoperatively. CONCLUSION: Improvement was not seen. Given the progressive nature of the disorder, evaluation over a longer period of time is necessary to detect if progression has stopped. Some modification to the surgical technique is needed to accomplish the same results as in human medicine. A study of a larger population is needed to attain more reliable information. CLINICAL RELEVANCE: Suboccipital craniectomy and dorsal laminectomy of C1 with durotomy and placement of a dural graft is a feasible technique in CKCS, but needs some modification to accomplish the same results as in human medicine.     

OCCIPITAL DYSPLASIA AND ASSOCIATED CRANIAL SPINAL CORD ABNORMALITIES IN TWO DOGS

Occipital dysplasia was found in association with cervical spinal cord abnormalities in two dogs. One dog presented for tetraparesis and cervical hyperesthesia, the other for historical cervical hyperesthesia and mild paraparesis. In dog 1, a midline cervical spinal cord defect consistent with a communicating syrinx was found. In the other dog, a presumptive syringo/hydromyelia of the cervical spinal cord was found on magnetic resonance imaging. While occipital dysplasia alone is not thought to cause any clinical abnormalities, the dogs of this report suggest that intramedullary central nervous system abnormalities may be present concurrently with occipital dysplasia and should be considered as a possible cause of the clinical signs. The relationship between occipital dysplasia and syringo/hydromyelia in these dogs remains unclear, however, similar associated abnormalities are occasionally found in humans with Chiari malformation.     

Morphologic and morphometric magnetic resonance imaging features of Doberman Pinschers with and without clinical signs of cervical spondylomyelopathy

OBJECTIVE: To compare morphologic and morphometric features of the cervical vertebral column and spinal cord of Doberman Pinschers with and without clinical signs of cervical spondylomyelopathy (CSM; wobbler syndrome) detected via magnetic resonance imaging (MRI). ANIMALS: 16 clinically normal and 16 CSM-affected Doberman Pinschers. PROCEDURES: For each dog, MRI of the cervical vertebral column (in neutral and traction positions) was performed. Morphologically, MRI abnormalities were classified according to a spinal cord compression scale. Foraminal stenosis and intervertebral disk degeneration and protrusion were also recorded. Morphometric measurements of the vertebral canal and spinal cord were obtained in sagittal and transverse MRI planes. RESULTS: 4 of 16 clinically normal and 15 of 16 CSM-affected dogs had spinal cord compression. Twelve clinically normal and all CSM-affected dogs had disk degeneration. Foraminal stenosis was detected in 11 clinically normal and 14 CSM-affected dogs. Vertebral canal and spinal cord areas were consistently smaller in CSM-affected dogs, compared with clinically normal dogs. In neutral and traction positions, the intervertebral disks of CSM-affected dogs were wider than those of clinically normal dogs but the amount of disk distraction was similar between groups. CONCLUSIONS AND CLINICAL RELEVANCE: The incidence of intervertebral disk degeneration and foraminal stenosis in clinically normal Doberman Pinschers was high; cervical spinal cord compression may be present without concurrent clinical signs. A combination of static factors (ie, a relatively stenotic vertebral canal and wider intervertebral disks) distinguished CSM-affected dogs from clinically normal dogs and appears to be a key feature in the pathogenesis of CSM.     

Morphometric dimensions of the caudal cervical vertebral column in clinically normal Doberman Pinschers, English Foxhounds and Doberman Pinschers with clinical signs of disk-associated cervical spondylomyelopathy

Client-owned, clinically normal Doberman Pinschers (n=20), English Foxhounds (n=17), and Doberman Pinschers with clinical signs of disk-associated cervical spondylomyelopathy (DA-CSM) (n=17) were prospectively studied. All dogs underwent magnetic resonance imaging (MRI) of the cervical vertebral column. To evaluate vertebral canal stenosis, the canal occupying ratios of the spinal cord and cerebrospinal fluid (CSF)-column were calculated from C5 to C7. To evaluate the degree of spinal cord compression and the amount of canal compromise, the compression ratio, remaining spinal cord and CSF-column area, and vertebral canal and dorsoventral vertebral canal compromise ratios were calculated at the site of most severe compression. For each canal occupying ratio, there was a significant higher value (implicating less space available for the spinal cord in the vertebral canal) at the level of C7 for clinically affected Doberman Pinschers compared with clinically normal English Foxhounds. The remaining spinal cord area was significantly smaller in dogs with clinically relevant spinal cord compression compared to dogs with clinically irrelevant spinal cord compression. Relative stenosis of the caudal cervical vertebral canal occurred more often in Doberman Pinschers with DA-CSM compared to English Foxhounds and a critical degree of spinal cord compression should be reached to result in clinical signs.     

Distribution of substance P and calcitonin gene-related peptide in the spinal cord of Cavalier King Charles Spaniels affected by symptomatic syringomyelia

The causes of clinical signs associated with syringomyelia in the Cavalier King Charles Spaniel (CKCS) are incompletely understood. In this study we compared expression of two pain-related neuropeptides: substance P (SP) and calcitonin gene related peptide (CGRP), in the spinal cord dorsal horn of normal dogs with that in CKCS with and without clinical signs of syringomyelia. There was a decrease in expression of both peptides in CKCS with 'symptomatic' syringomyelia that was also associated with significant asymmetry in SP-I and similar, though non-significant, asymmetry in CGRP-I compared with other groups. The asymmetric distribution of these pain-related peptides may be a consequence of syrinx-associated damage to grey matter but may also play a role in generation of pain.     

Inheritance of occipital bone hypoplasia (Chiari type I malformation) in Cavalier King Charles Spaniels

Occipital bone hypoplasia with foramen magnum obstruction and secondary syringomyelia (SM) is a common condition in the Cavalier King Charles Spaniel (CKCS) that is similar to human Chiari type I malformation. A worldwide family tree of more than 5,500 CKCSs spanning a maximum of 24 generations was established by obtaining pedigree information from 120 dogs diagnosed with SM secondary to occipital bone hypoplasia. The ongoing study showed 6 of 8 great grandparents of all affected dogs could be traced back to 2 female ancestors so that all 8 were descended from one or the other or both. The disease appears to be more severe and have an earlier onset with increased inbreeding, especially when breeding from affected dogs. The family tree of idiopathic epilepsy (IE) appears to be a different subset of the CKCS population, although some overlap was observed. Idiopathic epilepsy is more frequent in lines originating from whole-color dogs. Selection for coat color is believed to have influenced the development of both occipital hypoplasia with secondary SM and IE. In addition, breeding guidelines to reduce the incidence of mitral valve disease have placed further pressures on the gene pool.     

Questionnaire‐based Analysis of Owner‐reported Scratching and Pain Signs in Cavalier King Charles Spaniels Screened for Chiari‐like Malformation and Syringomyelia

Background

Chiari‐like malformation (CM) and syringomyelia (SM) cause a pain syndrome in Cavalier King Charles spaniels (CKCS). Clinical signs are not consistently apparent on neurologic examination, and owner reporting of signs provides vital clinical history. However, owner questionnaires for this disease are not well developed.

Objectives

To develop a tool to capture owner‐reported clinical signs for use in clinical trials and to compare owner‐reported signs with the presence of pain on neurologic examination and SM on magnetic resonance imaging (MRI).

Animals

Fifty client‐owned CKCS.

Methods

Owners completed a questionnaire and pain/scratch map. Each dog underwent a neurologic examination and craniocervical magnetic resonance imaging (MRI). Questionnaire responses were developed into scores, area of shading for pain/scratch maps was measured, and consistency of responses between these tools was assessed. Owner‐reported findings were compared with neurologic examination findings and presence and severity of SM on MRI.

Results

Thirty‐three dogs were symptomatic and 17 asymptomatic; 30 had SM. The most common sign of pain was crying out when lifted (n = 11). Extent of shaded areas on maps positively correlated with questionnaire scores for pain (r² = 0.213, P = 0.006) and scratch (r² = 0.104, P = 0.089). Owner‐reported findings were not significantly associated with presence or severity of SM or neurologic examination findings. Owner‐reported lateralization of signs was significantly associated with SM lateralization (P < 0.0001).

Conclusions

The questionnaire and maps may be useful for clinical trials. Lack of association of owner‐reported signs with SM highlights our lack of understanding of the pathophysiology of pain in this disease.     

MAGNETIC RESONANCE IMAGING OF THE CERVICAL SPINE IN 27 DOGS

The cervical spine of 27 dogs with cervical pain or cervical myelopathy was evaluated using magnetic resonance imaging (MRI). Spin echo T1, T2, and post-contrast T1 weighted imaging sequences were obtained with a 0.5 Tesla magnet in 5 dogs and a 1.5 Tesla magnet in the remaining 22 dogs. MRI provided for visualization of the entire cervical spine including the vertebral bodies, intervertebral discs, vertebral canal, and spinal cord. Disorders noted included intervertebral disc degeneration and/or protrusion (12 dogs), intradural extramedullary mass lesions (3 dogs), intradural and extradural nerve root tumors (3 dogs), hydromyelia/syringomyelia (1 dog), intramedullary ring enhancing lesions (1 dog), extradural synovial cysts (1 dog), and extradural compressive lesions (3 dogs). The MRI findings were consistent with surgical findings in 18 dogs that underwent surgery. Magnetic resonance imaging provided a safe, useful non-invasive method of evaluating the cervical spinal cord.     

One-year clinical and magnetic resonance imaging follow-up of Doberman Pinschers with cervical spondylomyelopathy treated medically or surgically

OBJECTIVE: To evaluate progression of clinical signs and magnetic resonance imaging (MRI) findings in dogs with cervical spondylomyelopathy (wobbler syndrome) treated medically or surgically. DESIGN: Prospective cohort study. ANIMALS: 12 Doberman Pinschers. PROCEDURES: Neurologic examinations and MRI were performed before medical (n = 9) or surgical treatment (ventral slot, 3) and a minimum of 12 months later. RESULTS: Mean follow-up time was 14.5 months. Clinically, 2 dogs improved after surgical treatment and 5 improved after medical treatment. Magnetic resonance imaging of surgically treated dogs revealed adequate spinal cord decompression. Spinal cord signal changes were seen in 2 dogs before surgery, both of which had new signal changes at the same and adjacent sites during follow-up examination. One dog treated surgically developed 3 new areas of spinal cord compression. In the medically treated dogs, the severity of spinal cord compression at the time of follow-up examination was unchanged in 4 dogs, worse in 2 dogs, and improved in 3 dogs, but spinal cord atrophy was observed on transverse images. Four medically treated dogs had changes in spinal cord signal initially, but none developed new signal changes or compressions. CONCLUSIONS AND CLINICAL RELEVANCE: Medical and surgical treatment improved or stabilized the clinical condition of most dogs. Surgical treatment appeared to hasten the development of additional areas of spinal cord compression and lesions in dogs with preoperative cord changes; however, the clinical importance of these changes was not determined. The progression of pathologic MRI abnormalities was notably less in medically treated dogs, compared with surgically treated dogs.     

Correlation between severity of clinical signs and motor evoked potentials after transcranial magnetic stimulation in large-breed dogs with cervical spinal cord disease

OBJECTIVE: To evaluate use of transcranial magnetic motor evoked potentials for assessment of the functional integrity of the cervical spinal cord in large-breed dogs with cervical spinal cord disease. DESIGN: Randomized, controlled, masked study. ANIMALS: 10 healthy large-breed control dogs and 25 large-breed dogs with cervical spinal cord diseases. PROCEDURE: Affected dogs were allocated to 3 groups on the basis of neurologic status: signs of neck pain alone, ambulatory with ataxia in all limbs, or nonambulatory. Transcranial magnetic stimulation was performed on each dog with the same standard technique. Motor evoked potentials (MEP) were recorded from electrodes inserted in the tibialis cranialis muscle. Following the procedure, each dog was anesthetized and cervical radiography, CSF analysis, and cervical myelography were performed. The MEP latencies and amplitudes were correlated with neurologic status of the dogs after correction for neuronal path length. RESULTS: Mean MEP latencies and amplitudes were significantly different between control dogs and dogs in each of the 3 neurologic categories, but were not significantly different among dogs in the 3 neurologic categories. A linear association was evident between MEP latencies and amplitudes and severity of neurologic deficits; the more severe the neurologic deficits, the more prolonged the latencies and the more decreased the amplitudes. CONCLUSIONS AND CLINICAL RELEVANCE: Transcranial magnetic MEP are useful to assess severity of cervical spinal cord disease in large-breed dogs. Impairment of the functional integrity of the cervical spinal cord was found even in dogs with neck pain alone.     

Cervical vertebral malformation-malarticulation syndrome in the Bernese mountain dog: clinical and magnetic resonance imaging features

O bjectives : To describe the clinical and magnetic resonance imaging features of cervical vertebral malformation-malarticulation in Bernese mountain dogs.
M ethods : Seven Bernese mountain dogs (four males and three females) were diagnosed with cervical vertebral malformation-malarticulation by magnetic resonance imaging. The following data were evaluated retrospectively: (1) abnormalities of the cervical vertebral column and spinal cord, (2) spinal cord compression, (3) intervertebral disc degeneration and herniation, (4) severity of clinical signs pretreatment and after treatment, (5) type of treatment and (6) outcome.
R esults : Spin echo T1-weighted and T2-weighted images disclosed multi-level, extradural compressive spinal cord lesions (ventral, dorsolateral or both) spanning from intervertebral disc spaces C3-4 to C6-7. In all seven dogs, T2-weighted images disclosed one or more intramedullary hyperintensities associated with extradural spinal cord compression. Surgery was performed in five dogs. Two dogs were managed medically. The prognosis for surgical or conservative management in Bernese mountain dogs was similar to cervical vertebral malformation-malarticulation in other breeds.
C linical S ignificance : Cervical vertebral malformation-malarticulation is an important differential diagnosis for young to middle-aged Bernese mountain dogs with a C1-5 or C6-T2 neuroanatomic localisation. Dorsolateral spinal cord compression associated with articular process hypertrophy was the most common feature of cervical vertebral malformation-malarticulation in the seven Bernese mountain dogs evaluated.