Osteological features in pure-bred dogs predisposing to thoracic or lumbar spinal cord compression

Thoracic vertebral canal stenosis in cats: clinical features, diagnostic imaging findings, treatment and outcome

OBJECTIVES

The aim of this study was to describe the clinical features, diagnostic imaging findings, treatment and outcome in cats with thoracic vertebral canal stenosis (TVCS).

METHODS

Medical records and imaging studies of cats with TVCS were retrospectively reviewed. Outcome was acquired from patient records and from owners or referring veterinary surgeons via a telephone questionnaire. For each case, breed-, age- and sex-matched controls were identified with CT imaging of the thoracic vertebral column. For each cat, vertebral canal height was determined at three levels for each thoracic vertebra. Vertebral canal heights were compared between control cats of different breeds and between affected and control cats of the same breed.

RESULTS

Nine TVCS cases were included. British Shorthairs and male neutered cats were over-represented (P <0.05). Median age at presentation was 9 years. All cats were presented for a chronic, progressive, painful, ambulatory, T3-L3 myelopathy. Five cats were treated conservatively, three surgically and one was euthanased. Two cats treated surgically demonstrated improvement of clinical signs and one demonstrated initial improvement followed by deterioration. Of the conservatively treated cats, three deteriorated and two improved. Compared with controls, affected cats had a lower vertebral canal height at multiple thoracic vertebral levels, being most prominent for British Shorthairs and domestic shorthairs (P <0.05). Unaffected British Shorthairs had a lower thoracic vertebral canal height at multiple levels than control domestic shorthairs (P <0.05).

CONCLUSIONS AND RELEVANCE

TVCS should be considered a differential diagnosis in middle-aged to older cats presenting with a chronic, progressive, painful, T3-L3 myelopathy. The predisposition of British Shorthairs could be explained by a narrower vertebral canal in this breed.

Cranial thoracic vertebral canal stenosis in three juvenile large-breed brachycephalic dogs treated by unilateral hemilaminectomy

Objective: To describe the surgical treatment and outcome for juvenile dogs with cranial thoracic vertebral canal stenosis treated by unilateral hemilaminectomy.

Study design: Case series.

Animals: Three large-breed brachycephalic dogs of various breeds (Dogue de Bordeaux, Australian Bulldog, Boerboel) with neurological signs consistent with a myelopathy of the third thoracic (T) to third lumbar (L) spinal cord segment.

Methods: Information on clinical presentation, diagnostic imaging, surgical procedures, postoperative complications, recovery and outcome is described.

Results: Neurological signs were present and progressive for two to four weeks prior to surgery and ranged from mild ataxia to paralysis. Cranial thoracic vertebral canal stenosis was diagnosed with computed tomography imaging. Lateral and dorsolateral spinal cord compression was present at multiple sites between T2 and T6. Alternating left and right-sided compressions were common. Surgical treatment was by unilateral, continuous hemilaminectomy over three to six vertebral spaces. Postoperative morbidity was minimal and return of independent ambulation was rapid (median: 13.5 days, range: 2–29 days). Neurological status in one dog worsened four months after surgery due to reoccurrence of osseous compression; unilateral hemilaminectomy was repeated in this dog. Long-term follow-up ranged from six to 10 months; neurological signs had completely resolved in one dog and substantially improved in the other two dogs.

Clinical significance: Unilateral hemilaminectomy was associated with rapid return of independent ambulation and substantial improvement in neurological scores.

Phenotyping of lumbosacral stenosis in Labrador retrievers using computed tomography

Deep phenotyping tools for characterizing preclinical morphological conditions are important for supporting genetic research studies. Objectives of this retrospective, cross-sectional, methods comparison study were to describe and compare qualitative and quantitative deep phenotypic characteristics of lumbosacral stenosis in Labrador retrievers using computed tomography (CT). Lumbosacral CT scans and medical records were retrieved from data archives at three veterinary hospitals. Using previously published qualitative CT diagnostic criteria, a board-certified veterinary radiologist assigned dogs as either lumbosacral stenosis positive or lumbosacral stenosis negative at six vertebral locations. A second observer independently measured vertebral canal area, vertebral fat area, and vertebral body area; and calculated ratios of vertebral canal area/vertebral body area and vertebral fat area/vertebral body area (fat area ratio) at all six locations. Twenty-five dogs were sampled (lumbosacral stenosis negative, 11 dogs; lumbosacral stenosis positive, 14 dogs). Of the six locations, cranial L6 was the most affected by lumbosacral stenosis (33%). Five of six dogs (83%) with clinical signs of lumbosacral pain were lumbosacral stenosis positive at two or more levels. All four quantitative variables were significantly smaller at the cranial aspects of the L6 and L7 vertebral foramina than at the caudal aspects (P < 0.0001). Fat area ratio was a significant predictor of lumbosacral stenosis positive status at all six locations with cranial L6 having the greatest predictive value (R² = 0.43) and range of predictive probability (25-90%). Findings from the current study supported the use of CT as a deep phenotyping tool for future research studies of lumbosacral stenosis in Labrador retrievers.

Estudo radiográfico da articulação lombossacra em cães das raças Pastor Alemão, Rottweiler e Doberman

Este trabalho teve como objetivo avaliar a variação entre diferentes raças das medidas radiográficas da articulação lombossacra. Foram utilizados 20 cães da raça Pastor Alemão, 20 cães da raça Rottweiler e 20 da raça Doberman. A articulação lombossacra foi avaliada radiograficamente com os membros pélvicos em posição neutra (N), em ventroflexão (VF) e dorsoextensão (DE). Foram mensurados os ângulos entre os processos articulares de L7 e S1 (PA), entre as epífises distal de L7 e proximal de S1 (EPIF), o ângulo lombossacro (LS), a amplitude de movimento (ROM) desses ângulos, o ponto de interseção das retas que formam esses ângulos e a respectiva ROM. Os resultados mostraram que a altura do canal vertebral em L7 é menor no Pastor Alemão (9,5mm) e maior no Rottweiler (10,5mm). O EPIF-DE foi maior no Pastor Alemão (38,03º). O PA-N foi menor no Pastor Alemão (15,98º). O LS-VF foi menor no Doberman (170,01º), e não diferiu entre o Pastor Alemão (179,17º) e o Rottweiler (176,61º). Os cães Pastores Alemães demonstraram uma maior ROM dos ângulos EPIF e LS. Concluiu-se que cães da raça Pastor Alemão apresentam maior instabilidade dessa articulação em relação às outras duas raças estudadas.

Comparison of cross sectional area and fat infiltration of the epaxial muscles in dogs with and without spinal cord compression

This study investigated the cross sectional area (CSA) and fat infiltration of the epaxial muscles in Dachshunds with compressive spinal cord lesions due to intervertebral disc herniation (IVDH) and in dogs with non-compressive spinal cord lesions with fibrocartilaginous embolism (FCE). The CSA and fat infiltration of the multifidi and longissimus dorsi muscles were determined from T1 weighted magnetic resonance images. Difference in CSA and fat infiltration between the lesion- and non-lesion side in the Dachshunds was assessed using mixed model analysis. Difference in CSA and fat infiltration between Dachshunds and FCE dogs was analysed with independent sample t-tests. There was no difference in CSA or fat infiltration between sides in the Dachshunds. FCE dogs had greater CSA (multifidus P = 0.036, longissimus P < 0.001) and less fat infiltration compared to Dachshunds (longissimus P = 0.017). Duration of neurological deficits, age, body size and conformation are likely to have influenced the difference between the groups.

Comparison between cranial thoracic intervertebral disc herniations in German Shepherd dogs and other large breed dogs

Cranial thoracic intervertebral disc herniations have been reported to be rare in dogs due to the presence of the intercapital ligament, however some studies have proposed they may not be uncommon in German Shepherd dogs. The purpose of this retrospective study was to compare cranial thoracic intervertebral disc herniations in German Shepherd dogs and other large breed dogs (control group). Medical records at the Ontario Veterinary College were searched for German Shepherd dogs and other large breed dogs that had magnetic resonance imaging studies including the T1-T9 region. For each dog and each disc space from T1-T9, three variables (compression, disc degeneration, and herniation) were recorded and graded based on review of sagittal T2-weighted images. Twenty-three German Shepherd dogs and 47 other large breed dogs met inclusion criteria. The German Shepherd dog group had higher scores than the control group for compression (P = 0.0099) and herniation (P < 0.001), but not disc degeneration (P = 0.97). In the German Shepherd dog group, intervertebral discs T2-T3 and T4-T5 had an increased risk for compression and T3-T4 had an increased risk for compression and herniation. Findings from this study indicated that German Shepherd dogs may be more likely than other large breed dogs to have spinal cord compression due to cranial thoracic disc herniations. Imaging of the cranial thoracic spine, including T2-T3, is recommended for German Shepherd dogs with T3-L3 neurological signs.