Phenotyping of lumbosacral stenosis in Labrador retrievers using computed tomography

Abstract

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 (R = 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.

Computed Tomographic Evaluation of the Sacroiliac Joints of Young Working Labrador Retrievers of Various Work Status Groups: Detected Lesions Vary Among the Different Groups and Finite Element Analyses of the Static Pelvis Yields Repeatable Measures of Sacroiliac Ligament Joint Strain

“…The study was a retrospective, secondary analysis, exploratory design. Labrador retriever working dogs, aged 11-48 months, that had undergone lumbosacral CT scanning for two, previous research studies were included (29,30). Due to the retrospective nature of the study, institutional animal care, and use committee approval was not required.…”

CT measures of lumbosacral paraspinal muscle size are not correlated with CT measures of lumbosacral stability in military working Labrador Retrievers

“…Lumbosacral stenosis was absent in seven dogs, present in one location in 12 dogs, and present in two or more locations in 20 dogs. More detailed descriptions of clinical, qualitative CT, and quantitative CT characteristics for each of the dogs are available in the previous publication …”

“…The study was a retrospective, secondary analysis, cross‐sectional design using military working Labrador Retrievers from a previous, prospective, research study . The original study sampled 40 dogs based on a power analysis.…”

“…using the following criteria. All CT examinations were performed at a single, tertiary referral, military working dog hospital (Daniel Holland Military Working Dog Hospital, Lackland Joint Base, Texas) between July 10, 2013 and July 17, 2013 . All dogs were purebred Labrador Retrievers, aged 1‐5 years, housed at the base during the study period, and with no clinical sign of disease that would be a contraindication for sedation and CT scanning.…”

Computed Tomographic Measures of Funnel-Shaped Lumbar Vertebral Canal and Articular Process Dysplasia Malformations Differ Between German Shepherd and Belgian Malinois Military Working Dogs

“…Breeding and procurement programs for working dogs aim to select dogs with the most desirable phenotypic traits for mission-specific working tasks and the highest likelihood for maximizing years of active duty service (1)(2)(3)(4)(5)(6). Development of quantitative, deep phenotyping methods is important for supporting researchers who study the criteria used by these programs because these methods allow the use of stronger statistical comparison tests (7). Clinical phenotyping can also be insensitive in stoic, high-drive working dogs due to their tendency to mask clinical signs until disease is advanced (2).…”