AUTHOR=Knell Sebastian C. , Smolders Lucas A. , Pozzi Antonio 

TITLE=Ex vivo Evaluation of the Dynamic Morphometry of the Caudal Cervical Intervertebral Disc Spaces of Small Dogs and Cats

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.706452

DOI=10.3389/fvets.2021.706452

ISSN=2297-1769

ABSTRACT=The objective of this study was to provide a morphometric description of the caudal cervical intervertebral disc (IVD) spaces of small-breed dogs and cats.
Specimens consisting of C4 through C7 from 5 small-breed dogs and 6 cats were positioned in neutral, flexion, extension, and lateral bending positions and CT images acquired. Height and width of the cranial and caudal vertebral end plates (VEP), angle between the VEPs (IVD wedge angle), and craniocaudal distance (IVD width) between VEPs for the 4 loading positions were measured and compared for three segments (C4-5, C5-6, and C6-7). VEP size normalized to bodyweight from medium-sized dogs was retrieved from a previous study and compared to data from small dogs and cats. A linear mixed model was used to compare outcome measures. Significance was set to P<0.05.
VEP size normalized to bodyweight was largest in small dogs compared to cats (P=0.0422) and medium-sized dogs (P=0.0064). Cats and medium-sized dogs were similar (P=0.2763) in these regards. Flexion and extension induced a reduction of IVD width in the ventral portion of the IVD and the area of the nucleus. The dorsal part of the IVD remained unchanged throughout loading conditions. 
Unique morphometric characteristics of the caudal cervical IVD space of small dogs and cats were detected that are different from those described in sizes of dog (medium-sized) typically affected by caudal cervical spondylomyelopathy (CSM). These findings may help to understand the different pathomechanisms in cervical spinal disease between small and medium sized dogs, including caudal cervical spondylomyelopathy.