| Summary: | 碩士 === 國立臺灣大學 === 臨床動物醫學研究所 === 105 === Syringomyelia (SM) is a condition characterized by fluid filled cavities within spinal cord, resulting spinal cord damage, neuropathic pain and neurological deficits. The most common cause of SM in the dog is Chiari-like malformation (CM). This study aims to evaluate the prevalence of symptomatic CM/SM in Maltese and Chihuahua in Taiwan, and the relationship between cervicocranial morphology and SM in these breeds.
Medical record of dogs admitted to National Taiwan University Veterinary Hospital between 2008 and 2017 were searched for dogs with MRI findings suggestive of CM+/-SM. Following data were collected, including age, breed, gender, clinical signs, MRI findings and diagnosis. Dogs with imaging evidence of increased intracranial pressure were excluded. The following parameters were measured on MRI T2W images: caudal cranial fossa (CCF) triangle area, basion-occipital crest distance, foramen magnum height, craniocervical junction (CCJ) ratio (CCJ height to CCF height ratio), basion-atlas distance, obex-foramen magnum distance, medullary angle (angle between ventral and caudal edge of medulla oblongata), medullary kinking (MK) index, dorsal compression (DC) index and atlantoaxial band compression grading. In addition, canine caseload with breed information over the same period of time was also analyzed for the prevelance study in symptomatic CM+/-SM dogs.
The prevalence of symptomatic CM/SM is 0.06% and 0.08% in Maltese and Chihuahua, respecctively. In 47 Maltese dogs with CM/SM on MRI, caudal cranial fossa (CCF) cross-section area, obex-foramen magnum distance and atlantoaxial band compression were associated with the severity of SM. In 19 Chihuahuas, measurements of spinal morphology (medullary kinking and dorsal compression index, atlantoaxial band compression) were associated with SM severity.
The prevalence of symptomatic CM/SM in Maltese and Chihuahua is higher than the prevalence in all breeds in this study. The cervicocranial morphometric analysis indicates decreased CCF volume and compensatively increased cranium height caused by brachycephalicism may be important factors in SM formation in Maltese. The data also emphasizes the role of CSF flow alteration in SM formation in both Maltese and Chihuahua. Future work should include larger sample size and longitudinal study to evaluate efficiency of these measurements as predictors of SM progression.
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