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Anomalous / Congenital

Developmental structural abnormalities of the spinal cord, meninges, local vasculature or the vertebrae can result in clinical signs of pain and or myelopathy but may be incidental findings on imaging studies

AA Subluxation

Atlanto-Axial Subluxation

Vertebral malformations

Vertebral Malformations

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Thoracolumbar myelopathies in Pug dogs

Multiple abnormalities have been described affecting the thoracolumbar spinal cord and vertebral column in pug dogs including constrictive myelopathy (CM), spinal arachnoid diverticulum (SAD), intervertebral disc herniations (IVDH), caudal articular process dysplasia (CAPD) and hemivertebrae. This retrospective study based on a cohort of 32 pugs dogs with a chronic, progressive T3-L3 myelopathy looks at 1) the frequency of CM with and without concurrent myelopathies based on diagnostic imaging and when available pathological findings and 2) whether there is a relationship between the sites of CM and other described T3-L3 myelopathies (such as IVDH and SAD) and sites and frequency of CAPD. Among other findings, this study reveals that:
- CAPD was present in 100% of the dogs in this cohort.
- There was no apparent relationship between anatomic locations of CAPD and most severe myelopathy or myelopathy type.
- Clinically there was a general progression toward development of fecal, urinary incontinence, or both within 6 months of initial clinical signs.
- The overlap of histopathological findings in CM, SAD, and IVDH in pug dogs might suggest that arachnoid fibrosis (common in all 3 conditions) is a reaction peculiar to that breed when there is irritation or compression of the spinal cord, regardless of site or diagnosis (eg. being a sequel or contributor to other myelopathies rather than a specific diagnosis).
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Comparison of signalment and computed tomography findings in French Bulldogs, Pugs, and English Bulldogs with and without clinical signs associated with thoracic hemivertebra

Interesting study looking at whether computed tomography (CT) findings and factors associated with signalment can be used to differentiate between dogs with and with-out neurological signs associated with hemivertebra. In this study, Pugs and a severe degree of kyphosis were considered the most important factors when considering a diagnosis of clinically relevant thoracic hemivertebra. Fewer as opposed to more hemivertebra along the vertebral column were also more often associated with clinical signs.
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Corpectomy and spinal stabilization using a 3D‐printed spine model and custom jigs to address severe spinal deformities from T9‐11 and L2‐4 in a 6‐month‐old German shepherd puppy

In this article, the authors described the surgical management of a 6 month old GSD with 2 hemivertebrae using hemilaminectomy/corpectomy and stabilization with guidance of a printed spine model and custom printed jigs.

Vascular Malformations

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Intramedullary vascular malformation in a dog

Intramedullary vascular malformations are a rare cause of myelopathy in dogs. This case report describes the MR findings, surgical treatment and outcome on a young adult dog with one-week history of progressive paraparesis, fecal and urinary incontinence.

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Myelopathy secondary to an intramedullary arteriovenous malformation in a mature dog

Vascular malformations affecting the spinal cord are rare in veterinary medicine. Vascular malformations of the CNS comprise capillary telangiectasia, cavernous malformation, venous angioma and arteriovenous (AV) malformation. The latter refers to direct arterial-venous communications without intervening capillary bed. In this article, the authors describe a 2 yrs old crossbreed dog presented with signs of progressive myelopathy. MRI and CT angiogram of the thoracic spinal cord showed multiple, distended, tortuous, anastomosing, intramural extramedullary vessels around the periphery of the spinal cord together with an intramedullary focus at T11 to T12 representing a complex vascular plexus.

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Spinal epidural arteriovenous fistula in 3 cats

Three young adult cats with intermittent spinal hyperesthesia and paraparesis and diagnosed with spinal epidural arteriovenous fistula are described. In all 3 cases, magnetic resonance imaging (MRI) showed focal dilatation of the veins in the epidural space of the thoracic spinal cord, whereas computed tomography angiography (CTA) showed dilatation and enhancement from the intercostal vein to the azygos vein at the same site in the arterial phase. Dorsal laminectomy and occlusion of the interarcuate branches running across the dorsal aspect of the spinal cord were performed in all 3 cats to decompress the spinal cord, which resulted in a remission of clinical signs.


Meningeal Malformations

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Short- and long-term outcome and magnetic resonance imaging findings after surgical treatment of thoracolumbar spinal arachnoid diverticula (SAD) in 25 Pugs

The aim of the this study was to describe clinical findings, short- and long-term outcomes, and follow-up magnetic resonance imaging (MRI) findings in Pugs with thoracolumbar SAD.

Mean age at presentation of the 25 dogs included was 7.32 (range 2-11) years and 80% were males. Short-term improvement was confirmed in 80% of dogs. Long-term deterioration was confirmed in 86% of cases, with late-onset recurrence of clinical signs after initial post-surgical improvement affecting 85% of Pugs. In 8 dogs with deteriorating clinical signs, follow-up MRI revealed regrowth of the SAD in 2 cases, new SAD formation in 2 cases, and intramedullary T2W hyperintensity / syringomyelia in 6 cases.

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Spinal Arachnoid Diverticula (SAD): Outcome in 96 Medically or Surgically Treated Dogs

The aim of this study was to describe the outcome of 96 dogs treated medically or surgically for SAD.

Of the 38 dogs treated surgically with available long-term follow-up, 82% improved, 3% remained stable and 16% deteriorated after surgery. Of the 37 dogs treated medically with available long-term follow-up, 30% improved, 30% remained stable, and 40% deteriorated.


This study suggests that surgical treatment was more often associated with clinical improvement compared to medical management.

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Thoracolumbar myelopathies in pug dogs

The aim of this study was to identify the frequency of constrictive myelopathy (CM) based on diagnostic imaging supplemented with necropsy; and 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).

Magnetic resonance imaging revealed 3/32 dogs with CM only, 17/32 with CM plus at least 1 other myelopathy, 11/32 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.

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Signalment, Clinical Presentation, and Diagnostic Findings in 122 Dogs with Spinal Arachnoid Diverticula (SAD)

The aim of this study was to describe SAD in 122 dogs with 125 SAD.

Sixty-five SAD were located in the cervical region and 60 in the thoracolumbar region. A higher body weight was significantly associated with a cervical localization of the SAD.

Based on this study, Pug dogs and French Bulldogs might have a predisposition for SAD development. In a large percentage of these dogs, a concurrent spinal disorder, which might predispose to SAD formation, was diagnosed.

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Caudal lumbar spinal cysts in two French Bulldogs

Two French Bulldogs, aged 5 and 8 years, were referred for evaluation of lower back pain and bilateral hind limb neurological deficits. Neurologic examination revealed ataxia and postural deficits in both dogs. Magnetic resonance imaging (MRI) showed cauda equina compression due to a cyst-like lesion at the level of L6–L7 in both cases. The dogs underwent dorsal laminectomy and the meningeal cyst was completely removed in one dog and in the other dog the spinal arachnoid diverticula was marsupialized. Both dogs were pain free during follow-up evaluations. The first case was diagnosed as a meningocele connected by a pedicle to the caudal tip of the dural sac forming a dural diverticulum categorized as an extradural spinal cyst type Ib, and the other as a type III intradural arachnoid diverticula.

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Surgical techniques used in the management of intra-arachnoid diverticula in dogs across four referral centres and their immediate outcome

Sub- or intra-arachnoid diverticula (SAD) are fluid dilations in the subarachnoid space that can cause compression of the spinal cord and an associated myelopathy. Surgical management has been described for thoracolumbar SAD with various procedures and approaches including hemilaminectomy, and dorsal laminectomy based on the location of the diverticulum with some variation of durotomy, durectomy, diverticulum fenestration, dural marsupialization and with stabilisation being advocated as well in some cases. To date, no one procedure appears superior and follow-up times are widely variable making assessment of success with each separate procedure difficult to determine. This recent study looks at the immediate postoperative outcome in 57 dogs treated for a single thoracolumbar SAD across 4 referral centres. The most common type of surgery was durectomy (28 dogs) followed by marsupialisation (11 dogs), durotomy alone (7 dogs), shunt placement (6 dogs) and stabilisation (5 dogs). This study did not identify an influence of surgical technique on short-term outcomes. Although dogs treated with shunt placement were likely to deteriorate in the immediate 24 hours post-op, they appear to improve by 3 to 5 weeks after surgery. The scope of this study was to look at complications and immediate post-operative outcomes and did not look at long-term outcome especially in term of which technique might be superior for preventing or reducing relapse which is a consideration in these cases, particularly in breeds like


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Thoracolumbar meningeal fibrosis in pugs


The aim of this paper was to further characterize the clinical and neuropathological characteristics of pugs with longstanding myelopathy. Thirty client-owned pure-bred pugs with a history of more than a month of ataxia and paresis of the pelvic limbs, suggesting a myelopathy localized to the thoracolumbar spinal cord, were included in the study.

Twenty male and 10 female pugs had a median age at clinical onset of 84 months. Affected pugs presented with a progressive clinical course and 80% were incontinent. There was circumferential meningeal fibrosis with concomitant focal, malacic, destruction of the neuroparenchyma in the thoracolumbar spinal cord in 24/30 pugs. Vertebral lesions accompanied the focal spinal cord lesion, and there was lympho-histiocytic inflammation associated or not to the parenchymal lesion in 43% of the pugs.

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