Abstract
In pugs, West Highland white terriers and other small breeds, congenital or acquired malformations/deviations of the spine are commonly reported, resulting, amongst other complications, in chronic meningeal compression and fibrosis, and interference with cerebrospinal fluid flow into the sub-arachnoid space. This leads to constrictive myelopathy (CM) which involves the constriction and consequent reduced diameter of the spinal cord accompanied by parenchymal damage (mostly gliosis). A11-year-old giant mixed breed male dog presented with ataxia in the hindlimbs, paresis, reduced proprioception, and normal reflexes. Neurolocalization was to the thoracolumbar spinal cord (T3-L3). Myelographic computed tomography and magnetic resonance imaging (MRI) of this tract showed spondylosis, multiple disc protrusions with mild cord compression, and reduced spinal cord diameter. Genetic test for SOD1 mutations performed to evaluate predisposition to degenerative myelopathy negative results; although poorly compressive, the symptoms were attributed to multiple disc protrusions, leading to spinal cord atrophy. The dog underwent physiotherapy and 23 months later, was more ataxic and paretic however still ambulatory; repeated MRI confirmed the previous findings, however, the onset of concomitant megacolon and a chronic kidney failure, induced the owner to euthanasia. Histopathological assessment indicated diffused remodeling of the meninges with progressive constriction of the spinal cord of concomitant megacolon and a chronic kidney failure, induced the owner to euthanasia. Histopathological assessment indicated diffused remodeling of the meninges with progressive constriction of the spinal cord. Altered distribution of the mechanical forces among the meningeal layers with stiffening of the ventral pachymeninges, probably caused by the disc protrusions, was considered the most likely trigger. To our knowledge, this is the first case reporting clinical, MRI and histological findings resembling an acquired constrictive myelopathy in a large-breed dog.
Highlights
Chronic and progressive hind limb ataxia and paresis due to thoracolumbar spinal cord injuries are quite frequent in adult or senior giant dogs
Chronic compression of the spinal cord due to multiple disc protrusions was considered the presumptive ante-mortem diagnosis, and neurological findings were attributed to spinal cord atrophy due to chronic compression, similar to those reported in previous studies (Griffiths 1972; Jeffery et al 2013)
The question regarding this patient could be: what really happened to the spinal cord? Why did it not show any signal alterations with reduced functionality? this study reports a single subject, it permits us to advance the hypothesis that chronic compression caused by the disc protrusions involves mechanical stimulation and irritation, leading to pathologic remodeling and consequent stiffening of the lepto- and pachymeninges with progressive constriction of the spinal cord (Fadda et al 2013) and that the alteration accompanies neurological symptoms
Summary
Chronic and progressive hind limb ataxia and paresis due to thoracolumbar spinal cord injuries are quite frequent in adult or senior giant dogs. This occurs because of several spinal cord diseases, such as chronic disc degeneration (disc protrusions), followed by degenerative myelopathies (DMs) and neoplasia [12]. DM is a neurodegenerative disease of the spinal cord that usually starts in the thoracolumbar tract of adult/senior dogs It causes demyelination and axonal degeneration mainly in the dorsolateral portion of the white matter of the spinal cord [9, 10]. In this study, we aimed to investigate the possible incidence and pathology of CM in an old and giant dog
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