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

Heather Dunn,Jeryl C Jones,Constance J Dragicevich,William Bridges

doi:10.3389/fvets.2020.00275

Abstract

Researchers who study the selection and breeding program criteria for military working dogs aim to help maximize the years of active duty service. Computed tomographic (CT) quantitative phenotyping has been previously described as a method for supporting these research studies. Funnel-shaped lumbar vertebral foramen malformations have been previously described in Labrador retriever military working dogs and proposed to be risk factors for impaired arterial perfusion of nerve tissues during exercise. Articular process dysplasia malformations have been previously described in varying dog breeds and proposed to be risk factors for articular process degenerative joint disease and vertebral foramen stenosis. Aims of this retrospective, cross-sectional study were to describe quantitative CT phenotyping methods for characterizing funnel-shaped lumbar vertebral foramina and articular process dysplasia malformations and to apply these methods in a comparison between groups of German shepherd and Belgian Malinois military working dogs. A military working dog hospital's database was searched for German shepherd and Belgian Malinois dogs aged <6 years that had CT scans of the lumbosacral region during the period of 2008–2016. Observers unaware of CT findings recorded available clinical data for each of the dogs. An observer unaware of clinical data recorded CT measures of funnel-shaped lumbar vertebral foramina and articular process dysplasia malformations for each of dogs and each of the lumbar vertebrae that were available in the scans. A total of 59 dogs were sampled: 41 German shepherd and 18 Belgian Malinois. Articular process dysplasia and funnel-shaped vertebral foramen phenotypic traits were present in both breeds in this sample, with the frequency and quantitative measure of these traits being greater in German shepherd dogs and heavier dogs. Lower weight dogs had a lesser degree of a funnel-shaped foramen at all sampled vertebral locations. A consistent relationship between articular process dysplasia measures and body weight was not seen. Computed tomography measures of funnel shaped vertebral foramina were greater in German shepherd vs. Belgian Malinois dogs at the L7 vertebra (P < 0.01). The CT measures of cranial articular process dysplasia were greater in German shepherd vs. Belgian Malinois dogs at the L4 (P < 0.01) and L5 (P < 0.05) vertebrae.

Highlights

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]
For inclusion in the study, dogs had to be German Shepherd or Belgian Malinois breed, and aged ≤6 years at the date of their first presentation for lumbosacral region Computed tomography (CT) scanning. Dogs of this age group were chosen based on a previous study reporting evidence that dogs younger than 6 years of age were more likely to successfully recover from treatment for lumbosacral stenosis [2]
Reasons listed for scanning in the “other” category of Table 2 included the following: tenesmus, hypertension, possible torn ureter, pain on palpation, previous lumbosacral surgery, left metacarpal five fracture, possible pain, and electromyography abnormalities

Summary

Introduction

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]. Degenerative joint disease and cauda equina syndrome have been reported to be important causes of death or euthanasia in military working dogs [1]. Lumbosacral disease has been reported to be a predominant cause of euthanasia or retirement in police working dogs [5]. German shepherd dogs and Belgian Malinois are widely used as police and military working dogs around the world [3, 5, 8]

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Conclusion