Thoracolumbar myelopathies in pug dogs

Abstract

Background Constrictive myelopathy (CM) involving a fibrous band around the spinal cord is a newly recognized disease in pug dogs. Objectives To identify the frequency of CM based on diagnostic imaging supplemented with necropsy; to determine whether a relationship exists between the sites of CM and other described T3‐L3 myelopathies; and to determine the frequency of caudal articular process dysplasia (CAPD). Animals Thirty‐two client‐owned pug dogs diagnosed with a chronic, progressive T3‐L3 myelopathy based on neurological examination performed by a board‐certified neurologist. Methods This is a prospective study. All dogs underwent computed tomography (CT) and magnetic resonance imaging (MRI) reviewed by a board‐certified radiologist. Magnetic resonance imaging abnormalities were categorized into diseases; CM only, CM plus other non‐CM condition(s), or non‐CM condition. Sites of CAPD were reported on CT. Nineteen dogs underwent necropsy. Results Magnetic resonance imaging revealed 3 dogs with CM only, 17 with CM plus at least 1 other myelopathy, 11 dogs with non‐CM myelopathies only, and 1 with no MRI abnormalities. Nineteen of 32 dogs had >1 myelopathy diagnosis on MRI whereas 15/32 had >1 site of spinal cord compression. All dogs had CAPD at >1 site in the T3‐L3 vertebral column on CT. Conclusions and Clinical Importance Constrictive myelopathy affected more than half of pug dogs presenting with chronic thoracolumbar myelopathies. Most had multilevel disease, concurrent myelopathies, or both. There was no apparent relationship between anatomic locations of CAPD and most severe myelopathy or myelopathy type.

Assessment of glial fibrillary acidic protein and anti‐glial fibrillary acidic protein autoantibody concentrations and necrotising meningoencephalitis risk genotype in dogs with pug dog myelopathy

“…38 The increased CSF GFAP concentrations in PDM pugs therefore suggest that they may have active, ongoing, CNS affection despite chronic clinical signs. Microtrauma, as a result of instability, related or unrelated to articular process abnormalities, 4,48,6 CNS inflammation 38 and intervertebral disc herniation, 5,7,9 could, by itself or in combination, be potential drivers of astrocyte damage and the continuous release of GFAP.…”

“…Progressive ataxia and paraparesis as a consequence of a thoracolumbar spinal cord disorder are common in pugs and appear worldwide. [1][2][3][4][5][6][7][8][9][10][11] Consistent clinical and pathological findings suggest that most of these disorders are caused by a specific condition; until now, only reported in pugs. 11 The terminology used to describe this condition has varied between publications, and has included constrictive myelopathy 4,7 and meningeal fibrosis.…”

“…11 However, constrictive myelopathy is associated with the presence of articular process abnormalities and does not include all pugs with this specific thoracolumbar myelopathy. 9 The use of a pathological term, meningeal fibrosis, is also not ideal when describing a clinical presentation. Therefore, the term pug dog myelopathy (PDM) will be used in this study to describe pugs clinically characterised by progressive signs involving the pelvic limbs, no apparent signs of pain, commonly observed incontinence and magnetic resonance imaging (MRI) confirmation of intradural compression and/or focal spinal cord T2W hyperintensity 3,7 or pathological confirmation of meningeal fibrosis and focal spinal cord destruction.…”

Pug thoracolumbar myelopathy: vertebral instability, immune‐mediated disorder or a combination of factors?

“…Some spinal disorders that have been associated with the pug breed are spinal arachnoid diverticulum, caudal articular process dysplasia (CAPD) and meningeal fibrosis or constrictive myelopathy. 3,4 These conditions can result in characteristic clinical signs of a slowly progressive myelopathy localised to the T3-L3 spinal cord segments without obvious spinal hyperaesthesia, with or without incontinence, in pugs over seven years old. 4 The aetiology of these disorders are incompletely understood and are characterised by overlapping clinical, diagnostic imaging and pathological abnormalities.…”

“…3,4 These conditions can result in characteristic clinical signs of a slowly progressive myelopathy localised to the T3-L3 spinal cord segments without obvious spinal hyperaesthesia, with or without incontinence, in pugs over seven years old. 4 The aetiology of these disorders are incompletely understood and are characterised by overlapping clinical, diagnostic imaging and pathological abnormalities. 3 This obviously complicates clinical decision making and has led to the introduction of the term 'pug dog myelopathy'.…”