Another pug disease.....

Veterinary Radiology & Ultrasound, 2020

Author

Obi Veterinary Education
August 12, 2025

Filipa Lourinho, Andrew Holdsworth, J. Fraser McConnell, Rita Gonçalves, Rodrigo Gutierrez-Quintana, Carles Morales, Mark Lowrie, Raquel Trevail, Ines Carrera

Background
Constrictive myelopathy is a condition described in Pugs with paraparesis, characterized by fibrous connective and granulation tissue within the dura mater, leading to spinal cord compression. This condition has been associated with caudal articular process (CAP) dysplasia, but its exact pathophysiology remains unclear. Previous studies have reported limited MRI descriptions of this disease. This study aimed to provide a detailed MRI characterization of constrictive myelopathy and its correlation with clinical signs in Pugs.

Methods
A multicenter retrospective study was conducted across five veterinary referral hospitals. Medical records of Pugs presenting with pelvic limb ataxia and paresis were reviewed. Inclusion criteria required a complete neurological examination and MRI of the thoracolumbar spinal cord. Cases with other spinal conditions, such as intervertebral disc disease or subarachnoid diverticula, were excluded. MRI images were evaluated for CAP dysplasia, subarachnoid space abnormalities, extradural lesions, spinal cord compression, and intramedullary changes. Clinical data, including onset, duration, progression, and presence of incontinence, were analyzed.

Results
Twenty-seven Pugs met the inclusion criteria. All dogs were ambulatory but exhibited paraparesis and ataxia, with 60% presenting urinary and/or fecal incontinence. MRI revealed a focal myelopathy in all cases, characterized by CAP dysplasia (92.6%), irregular subarachnoid space margins (96.3%), and a symmetric V-shaped ventral extradural lesion (85.2%). Intramedullary hyperintensity on T2-weighted images was present in all dogs, while 10 of 12 post-contrast studies showed circumferential or dorsal meningeal contrast enhancement. The myelopathy was predominantly located in the caudal thoracic spine (T10–L1). Histopathology from one case confirmed fibrosis within the dura mater.

Limitations
This study was retrospective, and histopathologic confirmation was only available for one case. The variability in MRI protocols between institutions may have influenced image interpretation. Additionally, Pugs with other spinal disorders were excluded, which may limit broader applicability of findings.

Conclusions
This study describes specific MRI features of constrictive myelopathy in Pugs, supporting its suspected association with CAP dysplasia and vertebral instability. The findings suggest that chronic micromotion may contribute to the development of fibrosis and spinal cord compression. Recognizing these MRI features may aid in diagnosing this condition and determining treatment options, including potential vertebral stabilization.

T2W parasagittal (A) and T1W transverse (B and C) MR images (3 mm slice thickness) and CT (D, E, and F) of the thoracolumbar vertebral column of a pug. The parasagittal planes demonstrate the difference between the anatomically intact (arrow heads) and aplastic (arrows) CAP on both MRI (A) and CT (D), which can also be appreciated in the transverse planes (B, C, E, and F), where the CAPs are absent on B and E (arrows) and present on C and F (arrows)

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