Constrictive myelopathy secondary to hypoplasia or aplasia of the thoracolumbar caudal articular processes in Pugs: 11 cases (1993-2009).

OBJECTIVE: To report thoracolumbar caudal articular process malformations with secondary constrictive fibrosis of the spinal cord in Pugs.
DESIGN: Retrospective case series. ANIMALS: 11 Pugs with neurologic dysfunction resulting from constriction of fibrous tissue secondary to thoracolumbar caudal articular process malformation and 5 Pugs with no neurologic dysfunction. PROCEDURES: Medical records of dogs with myelopathy presumably caused by constriction of fibrous tissue secondary to thoracolumbar caudal articular process malformation at 2 referral institutions between 1993 and 2009 were reviewed. Dogs were included in the study if hypoplastic or aplastic thoracolumbar caudal articular processes were present on radiographs, CT images, or MRI images.
RESULTS: The most common neurologic examination findings were paraparesis with ataxia or paraplegia but no evidence of hyperpathia along the vertebral column. All dogs' neurologic lesion localization was to the T3-L3 spinal cord segments. Median age at examination was 7. 7 years (range, 2 to 11 years). Five of 11 dogs had a history of unrelated trauma. Four of 11 dogs had urinary or fecal incontinence. Eight of 11 dogs underwent surgical exploration. Despite surgical intervention, all dogs that survived surgery continued to have neurologic deficits. CONCLUSIONS AND CLINICAL RELEVANCE: In the present study, presence of aplastic or hypoplastic articular processes in the thoracolumbar region did not always produce neurologic signs. However, fibrous constrictive myelopathy should be considered in Pugs with pelvic limb gait and postural reaction deficits and lack of hyperpathia upon palpation of the vertebral column. Additional studies are warranted to further characterize the disease process and determine the most effective means of treatment.