Comparative functional anatomy of the epaxial musculature of dogs (Canis familiaris) bred for sprinting vs. fighting

Posture and postural dysfunction in dogs: Implications for veterinary physiotherapy

Postural assessment is an important part of the veterinary evaluation of a dog's neuromusculoskeletal function. It forms an important part of the clinical examination by physiotherapists and specialists in veterinary rehabilitation and sports medicine and is well researched in humans, which has allowed treatment approaches to be developed and validated. This narrative review aims to complement the veterinary literature, which largely quantifies the impact of various conditions on posture, by synthesising the physiotherapy literature, to help translate the use of postural assessment as a basis for the development and validation of treatment techniques to improve outcomes in dogs.

Functional measurement of canine muscular fitness: refinement and reliability of the Penn Vet Working Dog Center Sprint Test

Working, sporting, and companion dogs require muscular fitness to perform their daily tasks, competitive activities, and operational functions effectively and with a low risk of injury. There are currently no methods to measure the muscular fitness of dogs who are not debilitated. Sprint performance is highly correlated with muscular fitness in humans, and various sprint assessments are used to measure performance for sporting and tactical athletes. The Penn Vet Working Dog Center Sprint Test (ST) is a 25 m maximal effort sprint from a down position and was developed to be a low-cost measure of muscular fitness suitable for field use. The purpose of this project was to describe the refinements to the ST, detail the performance and measurement protocol, evaluate the measurement inter-rater and intra-rater reliability, characterize the acceleration profile, and explore the inter-day reliability. Both naïve and experienced raters demonstrated excellent intra-rater and inter-rater reliability. The acceleration profile of the dogs in this study was similar to that of average adult human sprinters and demonstrated the role of muscular fitness in performance over this short distance. Finally, a small group of dogs showed moderate inter-day reliability and provided initial performance data to inform future studies. The ST appears to be a reliable measure of canine muscular fitness and could be used to assess performance in healthy dogs and guide the return to sport or work of debilitated dogs.

Ultrasonography of the paralumbar muscles as a new aid during melarsomine treatment in canine heartworm disease. Description and illustration of the method - A preliminary study

Melarsomine is used intramuscularly to destroy adult heartworms when treating canine heartworm disease (HWD). This drug is highly irritative and can elicit local complications. Therefore, melarsomine should be injected into the paralumbar muscles by strictly adhering to the manufacturers' prescriptions. However, it is not known how to determine the optimal location of the needle during the injection process. Ultrasonography (US) of the epaxial (paralumbar) musculature was used as a new method to measure the cross-sectional diameter of the paralumbar musculature, to determine the required location of the injection needle, and to study the local side effects in two dogs with HWD. The macroscopic appearance of the melarsomine solution during injection was demonstrated by video imaging. Melarsomine was not fully gravitating, but its majority was spreading along the thickest fascia of the musculature. Three minutes thereafter, no ultrasound signs of the melarsomine solution were seen, suggesting a full absorption at least ultrasonographically. This procedure was simulated in vitro with methylene blue solution having the same appearance. Removing the injection needle only after 5 min post-injection could prevent undesirable leakage of the drug through the injection channel into the subcutaneous tissue. Ultrasonography can be a useful aid during the treatment of HWD with melarsomine according to this preliminary study.

From fibre to function: are we accurately representing muscle architecture and performance?

The size and arrangement of fibres play a determinate role in the kinetic and energetic performance of muscles. Extrapolations between fibre architecture and performance underpin our understanding of how muscles function and how they are adapted to power specific motions within and across species. Here we provide a synopsis of how this 'fibre to function' paradigm has been applied to understand muscle design, performance and adaptation in animals. Our review highlights the widespread application of the fibre to function paradigm across a diverse breadth of biological disciplines but also reveals a potential and highly prevalent limitation running through past studies. Specifically, we find that quantification of muscle architectural properties is almost universally based on an extremely small number of fibre measurements. Despite the volume of research into muscle properties, across a diverse breadth of research disciplines, the fundamental assumption that a small proportion of fibre measurements can accurately represent the architectural properties of a muscle has never been quantitatively tested. Subsequently, we use a combination of medical imaging, statistical analysis, and physics-based computer simulation to address this issue for the first time. By combining diffusion tensor imaging (DTI) and deterministic fibre tractography we generated a large number of fibre measurements (>3000) rapidly for individual human lower limb muscles. Through statistical subsampling simulations of these measurements, we demonstrate that analysing a small number of fibres (n < 25) typically used in previous studies may lead to extremely large errors in the characterisation of overall muscle architectural properties such as mean fibre length and physiological cross-sectional area. Through dynamic musculoskeletal simulations of human walking and jumping, we demonstrate that recovered errors in fibre architecture characterisation have significant implications for quantitative predictions of in-vivo dynamics and muscle fibre function within a species. Furthermore, by applying data-subsampling simulations to comparisons of muscle function in humans and chimpanzees, we demonstrate that error magnitudes significantly impact both qualitative and quantitative assessment of muscle specialisation, potentially generating highly erroneous conclusions about the absolute and relative adaption of muscles across species and evolutionary transitions. Our findings have profound implications for how a broad diversity of research fields quantify muscle architecture and interpret muscle function.

Minimal Invasive Fluoroscopic Percutaneous Lateral Stabilization of Thoracolumbar Spinal Fractures and Luxations Using Unilateral Uniplanar External Skeletal Fixators in Dogs and Cats

OBJECTIVE

 The aim of this study was to describe minimally invasive spinal stabilization using a unilateral uniplanar external skeletal fixator (ESF, type 1a) with polymethylmethacrylate, and to review short- and long-term outcomes and complications in a clinical case series.

MATERIALS AND METHODS

 Medical records from animals affected by spinal fracture luxation were reviewed. The data included breed, age, gender, body weight, aetiology, preoperative and postoperative neurological state, radiographic findings, surgical treatment, pin size, number of pins and stabilized vertebrae, intra- and postoperative complications and neurological state at re-examinations.

RESULTS

 Thirty-two animals were identified; three were treated conservatively, 19 surgically and 10 were euthanatized. In eight dogs and six cats, the injured spinal column was treated with a laterally applied percutaneous type 1a ESF under fluoroscopic guidance. Positive profile end-threaded pins inserted were from 1.6/1.9 to 3.5/4.3 mm in dogs and 1.6/1.9 to 2/2.3 mm in cats and were placed into two to five vertebral bodies. At the re-examinations, the neurological status had improved in 12 animals, deteriorated in one, and was unchanged in another one. In eight cases, no complications were detected. The most common complications included erythema, exudation and pin loosening.

CONCLUSION

 The present work shows that type 1a ESF can be successfully and minimally invasively applied to fractures and luxations of the spine in dogs and cats with minimal major complications.

Revision of the morphology of longissimus capitis, longissimus atlantis, longissimus cervicis, and the cranial part of longissimus thoracis in the domestic goat (Capra hircus): a cadaveric study

Veterinary anatomical texts have generally described the longissimus muscle only in terms of its attachment in the ox as the basic species and have not thoroughly addressed its morphology in small ruminants. Hence, the present study was designed to present the anatomical features of longissimus capitis, longissimus atlantis, longissimus cervicis, and the cranial part of longissimus thoracis of domestic goats by comparing them with the existing descriptions of these muscles in the ox. Bilateral dissections of the neck and the cranial thoracic regions of 10 domestic adult goats of both sexes were carried out. The longissimus capitis and longissimus atlantis consisted of about 5 muscle slips originating from the articular processes of C3-C7 (including their bony ridges) or T1 and the transverse process of T2. In 7 (37%) of the 19 muscles dissected, the last slips in the longissimus capitis and longissimus atlantis or in one of them showed no attachment to the vertebrae. Rather, the thoracolumbar fascia in the cranial part of the thoracic region, the cranial edge or the deep face of longissimus thoracis, and the deep face of longissimus cervicis served as the origins of the muscles. The attachment sites of the longissimus cervicis and the cranial part of the longissimus thoracis in the goat demonstrated no remarkable differences with those of the ox. Whether the attachment sites of these variants should be considered as normal or anomalous needs to be evaluated with a larger number of animals of different breeds.

Age-related change in shear elastic modulus of the thoracolumbar multifidus muscle in healthy Beagle dogs using ultrasound shear wave elastography

Background

Multifidus muscle stiffness decreases in patients with lumbar intervertebral disk herniation; however, age-related changes in humans have not been reported.

Objectives

The reliability of ultrasound shear wave elastography in dogs, and changes in the shear elastic modulus of the thoracolumbar multifidus muscle with aging in dogs, were investigated.

Methods

Twelve beagle dogs were divided into 2 groups based on the age of onset of intervertebral disk herniation: young (aged not exceeding 2 years; 1.3 ± 0.6 years old, n = 5) and adult (4.9 ± 1.2 years old, n = 7). The shear elastic modulus of the multifidus muscle, from the thirteenth thoracic spine to the fourth lumbar spine, was measured using ultrasound shear wave elastography. The length, cross-sectional area and muscle to fat ratio of the multifidus muscle, and the grade of intervertebral disk degeneration, were assessed using radiographic and magnetic resonance imaging examinations.

Results

The length and cross-sectional area of the multifidus muscle increased caudally. In the young group, the shear elastic modulus of the multifidus muscle of the thirteenth thoracic spine was less than that of the third lumbar spine. In the adult group, the shear elastic modulus of the multifidus muscle of first and third lumbar spine was lower than that of the same site in the young group.

Conclusions

Ultrasound can be used to measure shear wave elastography of the thoracolumbar multifidus in dogs. If the multifidus muscle stiffness decreases, we should consider age-related change.

Fetal development and growth of the human erector spinae with special reference to attachments on the surface aponeurosis

PURPOSE

The longissimus (LO) and iliocostalis (IC) of adults consist of myofibers extending from the superolateral to the inferomedial side of the back and, because of the same course, they are fused in the thoracolumbar region. The LO also has a medial attachment to the long myofibers of the transversospinalis (TS) showing a course from the superomedial to the inferolateral side. However, there is apparently no information regarding when and how these similar longitudinal muscles differentiate from a cluster of dorsomedial myotome cells.

METHODS

We examined sagittal and horizontal sections of the trunks of 39 human embryos and fetuses (18-330 mm crown-rump length).

RESULTS

At 6-7 weeks gestational age (GA), the surface aponeurosis appeared prior to and independent of the thoracolumbar fascia. At 6-9 weeks GA, the LO myofibers had a postero-inferior course, from the transverse process to the initial aponeurosis, whereas the TS myofibers had a postero-superior course, from a lateral extension of the intertransverse ligament to the aponeurosis. However, the IC consisted of supracostal longitudinal myofibers and was distant from the LO until 12 weeks GA. Because of the lack of ligamentous attachments and ribs, myofibers of the TS, LO, and IC took a similar inferior course in the lumbar region. When the early TS was represented by the transverso-aponeurotic muscle, consequently, the LO corresponded to the aponeuro-transversal muscle and was independent from the IC.

CONCLUSION

The classical model of TS and LO development does not recognize the essential role of the aponeurosis identified here.

Working Dog Structure: Evaluation and Relationship to Function

Working dogs help to keep society and individuals safe, secure, and healthy. To perform their varied functions, it is critical to select dogs that are structurally sound and capable of demonstrating power, coordination and agility. Characteristics such as size and substance, head and axial skeletal structure, chest size and conformation, and thoracic and pelvic limb angulation should be evaluated to select the optimal combination of characteristics to suit the tasks to which each dog will be assigned. This review provides guidance on how to evaluate each of these structural components and discusses the contributions of those body parts to a working dog's function.

Parallel Spine Design and CPG Motion Test of Quadruped Robot

The spine of mammals aids in the stability of locomotion. Central Pattern Generators (CPGs) located in spinal cord can rapidly provide a rhythmic output signal during loss of sensory feedback on the basis of a simulated quadruped agent. In this paper, active spine of quadruped robot is shown to be extremely effective in motion. An active spine model based on the Parallel Kinematic Mechanism (PKM) system and biological phenomena is described. The general principles involved in constructing a neural network coupled with limbs and spine to solve specific problems are discussed. A CPG mathematical model based on Hopf nonlinear oscillators produces rhythmic signal during locomotion is described, where many parameters to be solved must be formulated in terms of desired stability, often subject to vertical stability analysis. Our simulations demonstrate that active spine with setting reasonable CPG parameters can reduce unnecessary lateral displacement during trot gait, improving the stability of quadruped robot. In addition, we demonstrate that physical prototype mechanism provides a framework which shows correctness of simulation, and stability can thus be easily embodied within locomotion.

Musculoskeletal mass and shape are correlated with competitive ability in male house mice (Mus musculus)

Intense physical competition between males for mating opportunities is widespread among mammals. In such agonistic encounters, males with combinations of morphological, physiological and behavioral characters that allow them to dominate an opponent have greater fitness. However, the specific physical traits associated with competitive ability are poorly understood. Larger body size is often correlated with fitness in mammals. Interestingly, fitness is maximized at intermediate body masses in male house mice (Mus musculus), a species with a polygynous mating system in which males compete physically for access to reproductive resources. Here, we used competition trials in semi-natural, mixed-sex population enclosures to directly measure competitive ability in male house mice based on control of a preferred nesting site. We tested the hypothesis that the musculoskeletal systems of male mice demonstrating high competitive ability are more specialized for competition by comparing the masses of 10 major muscle groups and eight bones as well as a set of 12 skeletal shape indices associated with anatomical specialization for fighting performance in a set of nine winners and 20 losers. Winning males possessed several traits hypothesized to enhance performance in male-male contests: relatively greater mass in several muscle groups and bones of the forelimb and hindlimb and larger scapular surface area. Unexpectedly, no measurements of the head and neck differed significantly between winners and losers. These results identify musculoskeletal traits associated with competitive ability in male house mice and suggest that our current understanding of mammalian fighting performance is incomplete and more nuanced than previously considered.

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

Management of degenerative lumbosacral stenosis in military working dogs more frequently utilizes core conditioning exercise programs. Future research on the effectiveness of these programs may benefit from an improved understanding of relationships between paraspinal muscle size and lumbosacral stability. The aim of this retrospective, secondary analysis, cross-sectional study was to test the following hypotheses related to CT measures: (a) transverse paraspinal muscle area ratios differ between hip flexion and extension, (b) lumbosacral angle and lumbosacral range of motion differ by lumbosacral angle measurement technique, and (c) transverse paraspinal muscle area ratios are correlated with CT measures of lumbosacral stability (parasagittal and parasagittal oblique foraminal area changes) regardless of hip position and with lumbosacral range of motion within each hip position. Lumbosacral CT scans in hip flexion and extension were retrieved from a previous prospective study of military working Labrador Retrievers. A single observer performed triplicate measurements of transverse paraspinal muscle area ratios, parasagittal foraminal area, and parasagittal oblique foraminal area for each hip position and another observer independently performed triplicate measurements of lumbosacral angle and lumbosacral range of motion at L7-S1 using two published techniques. Thirty-nine dogs were analyzed and significant differences were identified between hip flexion and extension for all mean transverse paraspinal muscle area ratio values (P ≤ .05). Mean lumbosacral angles also significantly differed between the published techniques in both hip flexion and extension. When comparing mean lumbosacral range of motion values, one of the published techniques produced significantly smaller values. No significant correlation was found between transverse paraspinal muscle area ratios and parasagittal foraminal area changes, parasagittal oblique foraminal area changes, or lumbosacral range of motion. These results should be considered when designing studies using these CT measures in military working dogs.

Structural characteristics and predicted functional capacities of epaxial muscles in chondrodystrophic and non-chondrodystrophic dogs with and without suspected intervertebral disc herniation- a preliminary study

Epaxial muscle atrophy is related to spinal diseases in dogs. However, the influence of intervertebral disc herniation (IVDH) on the functional capacity of epaxial muscles has not been investigated. We aimed to estimate force and power-generating capacity of epaxial muscles in chondrodystrophic Dachshunds and non-chondrodystrophic Border terriers bred for similar purposes. Further we aimed to compare these features in Dachshunds with and without IVDH. Cadavers of Dachshunds (n = 16) and Border terriers (n = 7) were investigated with MRI. In the absence of clinical information, MRI findings were used to categorize the Dachshunds into affected (n = 8) and non-affected (n = 8). Epaxial muscle mass, muscle belly length, fascicle length, architectural index and physiological cross-sectional area (PCSA) were obtained through dissections, pain and exercise history through questionnaires. Difference between groups and effect of covariates were assessed with ANCOVA models. Dachshunds had greater muscle mass in M. splenius, M. longissimus capitis and M. iliocostalis thoracis (all P < .05). Dachshunds had higher PCSA in M. semispinalis complexus (P = .004) and M. iliocostalis lumborum (P = .016) than Border terriers, which had longer muscle fascicles in these muscles (P = .004 and P = .002, respectively). Affected Dachshunds had longer muscle fascicles than non-affected Dachshunds in M. longissimus thoracis et lumborum (P = .004) and M. longissimus cervicis (P = .011). Body weight had a significant impact on all muscle variables, but pain and exercise had none. Dachshund epaxial muscles have greater potential for force production than those of the Border terrier. This may imply that Dachshunds, due to predisposition to IVDH, require more spinal stability provided by the epaxial muscles.

Connecting muscle development, birth defects, and evolution: An essential role for muscle connective tissue

Skeletal muscle powers all movement of the vertebrate body and is distributed in multiple regions that have evolved distinct functions. Axial muscles are ancestral muscles essential for support and locomotion of the whole body. The evolution of the head was accompanied by development of cranial muscles essential for eye movement, feeding, vocalization, and facial expression. With the evolution of paired fins and limbs and their associated muscles, vertebrates gained increased locomotor agility, populated the land, and acquired fine motor skills. Finally, unique muscles with specialized functions have evolved in some groups, and the diaphragm which solely evolved in mammals to increase respiratory capacity is one such example. The function of all these muscles requires their integration with the other components of the musculoskeletal system: muscle connective tissue (MCT), tendons, bones as well as nerves and vasculature. MCT is muscle's closest anatomical and functional partner. Not only is MCT critical in the adult for muscle structure and function, but recently MCT in the embryo has been found to be crucial for muscle development. In this review, we examine the important role of the MCT in axial, head, limb, and diaphragm muscles for regulating normal muscle development, discuss how defects in MCT-muscle interactions during development underlie the etiology of a range of birth defects, and explore how changes in MCT development or communication with muscle may have led to the modification and acquisition of new muscles during vertebrate evolution.

Functional myology of the thoracic limb in Pampas fox (Lycalopex gymnocercus): a descriptive and comparative analysis

The characteristics of the muscles of the thoracic limb were evaluated in 22 specimens of Lycalopex gymnocercus. Descriptive and comparative analyses showed similarity with other canids in terms of topography and tendon insertions. Differences with the domestic dog were observed in the pectoralis profundus, triceps brachii and interflexorii muscles. Intraspecific variations were observed in the rhomboideus capitis, serratus ventralis cervicis, extensor carpi radialis, extensor digiti I and II, lumbricales, flexor digiti I brevis, abductor digiti I brevis, and flexor digiti V muscles. The analyses of muscle architecture carried out in nine specimens showed that there was no difference in muscle percentage mass in the thoracic limb of males and females, but a young specimen showed significant lower percentage mass. The triceps brachii caput longus muscle showed the greatest mass, the subscapularis muscle showed the greatest physiological cross-sectional area value, and the extrinsic muscles, in general, presented the longest fascicles and higher architectural indexes. Muscle architecture data were compatible with those of a thoracic limb adapted to fast cursorial locomotion that prioritizes movements in a sagittal plane instead of rotation or adduction/abduction. There was a high association between functional percentage mass of the muscles in the thoracic limb and phylogeny in the Carnivora order. It may be inferred that carnivoran muscle mass is largely determined by phylogeny.

Effect of water depth on muscle activity of dogs when walking on a water treadmill

Evidence-informed practice is currently lacking in canine hydrotherapy. This study aimed to investigate if the estimated workload of the gluteus medius (GM) and longissimus dorsi (LD) increased in dogs at different water depths when walking on a water treadmill. Seven dogs were walked for 2 min continuously on a water treadmill at depths of no submersion (depth 1), mid-tarsal (depth 2), between lateral malleolus and lateral epicondyle (depth 3) and between the lateral epicondyle and greater trochanter (depth 4). Continuous electromyographic data from the right and left sides of GM and LD were collected simultaneously during exercise. Friedman’s analyses with post-hoc Wilcoxon tests established if significant differences in GM and LD muscle activity occurred between the water depths for mean estimated-workload. Significant differences occurred in estimated-workload in GM and LD between water depths (P<0.05). Mean estimated-workload decreased in the right and left GM between depths 2 (mid-tarsal) and 3 (between lateral malleolus and epicondyle) (P<0.007) and depths 2 and 4 (between lateral epicondyle and greater trochanter) (P<0.001), a pattern which was repeated for left and right LD (P<0.007). Right GM mean estimated-workload increased between depth 1 (no submersion) and depth 2 only (P<0.013). Water depth influences GM and LD activity in dogs walking on a water treadmill. Increasing knowledge of canine locomotion in water treadmills could be used to inform individualised rehabilitation regimes for dogs undertaking hydrotherapy.

Phenotypic disparity of the elbow joint in domestic dogs and wild carnivores

In this article, I use geometric morphometrics in 2D from a sample of 366 elbow joints to quantify phenotypic disparity in domestic dog breeds, in wild canids, and across the order Carnivora. The elbow joint is a well-established morphological indicator of forearm motion and, by extension, of functional adaptations toward locomotor or predatory behavior in living carnivores. The study of the elbow joint in domestic dogs allows the exploration of potential convergences between (i) pursuit predators and fast-running dogs, and (ii) ambush predators and fighting breeds. The results indicate that elbow shape disparity among domestic dogs exceeds than in wolves; it is comparable to the disparity of wild Caninae, but is significantly lower than the one observed throughout Canidae and Carnivora. Moreover, fast-running and fighting breeds are not convergent in elbow joint shape with extreme pursuit and ambush wild carnivores, respectively. The role of artificial selection and developmental constraints in shaping limb phenotypic disparity through the extremely fast evolution of the domestic dog is discussed in the light of this new evidence.

Biomechanics of predator-prey arms race in lion, zebra, cheetah and impala

The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator-prey pairs, lion-zebra and cheetah-impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator-prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate.

Muscle activation during maximal effort tasks: evidence of the selective forces that shaped the musculoskeletal system of humans

The selective forces that played a role in the evolution of the musculoskeletal system of the genus Homo have long been debated and remain poorly understood. In this investigation, we introduce a new approach for testing alternative hypotheses. Our analysis is based on the premise that natural selection can be expected to have resulted in muscles that are large enough to achieve necessary levels of maximum performance in essential behaviors, but not larger. We used surface electromyography in male subjects to identify maximum activation levels in 13 muscles of the back and leg during eight behaviors that have been suggested to have been important to foraging, hunting and fighting performance in early humans. We asked two questions: (1) what behaviors produce maximum activation in each of the investigated muscles and (2) are there specific behaviors that elicit maximum recruitment from all or most of the muscles? We found that in eight of the 13 muscles, the highest activity occurred during maximal effort vertical jumping (i.e. whole-body acceleration). Punching produced the highest median activity in the other five muscles. Together, jumping and punching accounted for 73% of the incidences of maximum activity among all of the muscles and from all of the subjects. Thus, the size of the muscles of the back and leg appear to be more related to the demands of explosive behaviors rather than those of high speed sprinting or sustained endurance running. These results are consistent with the hypothesis that selection on aggressive behavior played an important role in the evolution of the genus Homo.

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.