A LUMBOSACRAL TRANSITIONAL VERTEBRA IN THE DOG PREDISPOSES TO CAUDA EQUINA SYNDROME

Transitional, fused and/or supernumerary vertebrae in the lumbosacrocaudal region of the spine - A reality in many domestic mammals

The aim of this study was to identify the presence of transitional lumbosacral and sacrocaudal vertebrae in domestic mammals, to realise a comparative analysis of the localisation and conformation of this abnormal condition. The research included the following species: cattle - 29 specimens, sheep - 32 specimens, horse - 31 specimens, pig - 26 specimens, rabbit - 33 specimens, dog - 89 specimens and cat - 57 specimens. The spine of the animals was analysed post-mortem or radiologically. The investigations revealed the presence of transitional vertebrae as follows: in cattle - 3 cases (8.7%), all being about the lumbarisation of the first sacral vertebra (S1); in sheep - 3 cases (9.37%), two lumbarisation cases of S1 and one caudalisation of S4 (the last sacral vertebra); in horses - 4 cases (12.9%), all about the sacralisation of Cd1 (first caudal vertebra); in pigs - 3 cases (11.53%), two lumbarisation cases of S1 and one sacralisation of Cd1; in rabbits - 3 cases (9.09%), a lumbar supernumerary vertebra (L8) and two cases of caudalisation of S4; in dogs - 4 cases (4.49%), a lumbar supernumerary vertebra (L8) and 3 cases of sacralisation of the last lumbar vertebra (L7 or L8); in cats - 3 cases (5.26%), two sacralisation cases of the last lumbar vertebra and one case of caudalisation of the last sacral vertebra (S3). A strong lumbarisation process was observed in ruminants (especially in cattle), then in pigs, the sacralisation being prevalent in carnivores. The sacrocaudal transitional vertebra was predominant in horses. No evident influence of the sex and age of the animals was observed.

Vertebral and spinal malformations in small brachycephalic dog breeds: Current knowledge and remaining questions

Small brachycephalic dog breeds, such as the French bulldog, English bulldog and pug have become increasingly popular. These breeds are predisposed to a variety of vertebral and spinal malformations, including hemivertebra, caudal articular process dysplasia, transitional vertebra, cranial thoracic vertebral canal stenosis, spinal arachnoid diverticulum and meningeal fibrosis. Recent studies have provided new insights into the prevalence, anatomical characteristics, pathophysiology and treatment of these conditions. Thoracic hemivertebra, caudal articular process dysplasia, transitional vertebra, and cranial thoracic vertebral canal stenosis occur commonly in neurologically normal dogs. Although the clinical relevance of these vertebral anomalies has therefore been questioned, severe kyphosis and hemivertebra in pugs have been associated with an increased likelihood of neurological signs. Meningeal fibrosis is characterised by the formation of dense intradural fibrotic adhesions, constricting the spinal cord. This condition has been heavily associated with the pug breed. It is in pugs further common to observe multiple concurrent spinal disorder in association with chronic progressive pelvic limb gait abnormalities. This clinical presentation has been referred to as 'pug dog thoracolumbar myelopathy' and potential genetic risk factors have recently been identified. Despite our increased knowledge, many questions remain currently unanswered. This review discusses our current understanding and controversies surrounding vertebral and spinal malformations in small brachycephalic dog breeds.

Lumbosacral transitional vertebra in 14 dog breeds in Norway: Occurrence, risk factors and association with hip dysplasia

A lumbosacral transitional vertebra (LTV) is a congenital anomaly of the spine and has been suggested to predispose to canine hip dysplasia (CHD). This retrospective, cross-sectional study investigated the prevalence of LTV and CHD among 14 dog breeds in Norway, the possible associations with risk factors, and whether LTV was a risk factor for the development of hip dysplasia. The results were based on evaluation of ventrodorsal radiographs from the CHD screening program from the Norwegian Kennel Club from February 2014 to January 2022. A total of 13,950 dogs were included in the study. For statistical analysis, CHD grades were reclassified from the official Federation Cynologique Internationale (FCI) grades into three grades: CHD free (CHD=A, B), CHD mild (CHD=C), and CHD severe (CHD=D, E). In the study sample, the overall occurrence of LTV was 18.5%, of which 32.9% were type 1, 45.7% type 2% and 21.4% type 3. The occurrence of LTV varied significantly among the included breeds, ranging from 9.5% to 46.2%. There was no association between sex and LTV. The frequencies of CHD grades were A: 43.1%; B: 31.4%; C: 18.4%; D: 6.0%; E: 1.1%. There was a statistically significant association with mild and severe CHD in dogs with LTV type 2 and LTV type 3 (P< 0.001). In the population studied, the prevalence of LTV was different among breeds. This supports initial data on the heredity of LTV and the diverse occurrence of LTV among breeds. Our results indicate that LTV type 2 and type 3 are associated with mild and severe CHD development. Therefore, this study has potentially identified an additional risk factor for the development of hip dysplasia.

[Long-term examinations of the lumbal disc and facet joint changes in 5 German Shepard dogs]

OBJECT AND PURPOSE

The purpose of this first-time long-term observational study was to evaluate the changes of the caudal lumbar spine at the locations L5/6, L6/7, and L7/S1 in 5 German shepherd dogs over a 6-year time period using computed tomography (CT) and magnetic resonance imaging (MRI). The dogs had a mean age of 26 months at the time of the first examination. In addition, it was evaluated whether a breeding examination, with regard to disc degeneration, is justified in young dog.

MATERIAL AND METHODS

The locations L7/S1, L6/7, and L5/6 were examined in more detail with regard to their signal intensity changes, the facet joint angle changes in dorsal (dors) and transverse (trans) planes, and disc surface changes in sagittal (sag) and transverse (trans) reconstruction planes with CT and MRT in 2015 and 2021. All data were collected computer-based and analyzed statistically. Subsequently, the results were compared to the measured signal intensity and to the subjective disc degeneration grading according to Seiler used in practice.

RESULTS

Over the period of 6 years a significant loss of the measured signal intensity of the intervertebral discs in the transverse plane and an overall facet joint widening in the transverse plane of 0.54° as well as in the dorsal plane of 1.8° was evident. In addition, there was no evidence of a relationship between the size of the facet joint angle and the degree of disc degeneration. Furthermore, regardless of the initial degree of degeneration, the discs showed low signal intensity and higher Seiler grade during follow-up.

CONCLUSION AND CLINICAL RELEVANCE

The results of the present study group indicate that an inconspicuous condition of the lumbar intervertebral discs at the time of the initial breeding examination in the young dog does not allow an accurate prediction of the subsequent degree of degeneration and that there are ongoing remodeling processes at the facet joints even in healthy German shepherd dogs.

Regulation of posterior Hox genes by sex steroids explains vertebral variation in inbred mouse strains

A series of elegant embryo transfer experiments in the 1950s demonstrated that the uterine environment could alter vertebral patterning in inbred mouse strains. In the intervening decades, attention has tended to focus on the technical achievements involved and neglected the underlying biological question: how can genetically homogenous individuals have a heterogenous number of vertebrae? Here I revisit these experiments and, with the benefit of knowledge of the molecular-level processes of vertebral patterning gained over the intervening decades, suggest a novel hypothesis for homeotic transformation of the last lumbar vertebra to the adjacent sacral type through regulation of Hox genes by sex steroids. Hox genes are involved in both axial patterning and development of male and female reproductive systems and have been shown to be sensitive to sex steroids in vitro and in vivo. Regulation of these genes by sex steroids and resulting alterations to vertebral patterning may hint at a deep evolutionary link between the ribless lumbar region of mammals and the switch from egg-laying to embryo implantation. An appreciation of the impact of sex steroids on Hox genes may explain some puzzling aspects of human disease, and highlights the spine as a neglected target for in utero exposure to endocrine disruptors.

Part II of Finnish Agility Dog Survey: Agility-Related Injuries and Risk Factors for Injury in Competition-Level Agility Dogs

Simple Summary

Agility dogs can get injured during sports performance. Only a few factors have been linked to risk for injury. Through an online questionnaire, information was collected of more than 860 Finnish competition-level agility dogs. Of these dogs, 119 (14%) had suffered an injury in agility during calendar year 2019. Front limbs were most commonly injured. Typically, the injury presented as lameness. In general, dogs regained their performance level in four weeks, but 10% of injured dogs retired from the sport due to the injury. Dogs with multiple previous agility-related injuries or a diagnosis of lumbosacral transitional vertebra had higher odds of getting injured. Other common factors among the injured dogs included older age when starting course-like training and more than two agility-training sessions a week. A moderate number of monthly competition runs and an A-frame performance technique had lower odds of injury. This study identified new risk factors for injury in agility. This information can be used to improve the welfare of agility dogs.

Abstract

Dog agility is associated with a risk for sport-related injuries, but few risk factors for injury are known. A retrospective online questionnaire was used to collect data on 864 Finnish competition-level agility dogs—including 119 dogs (14%) with agility-related injury during 2019. Data included injury details, health background, experience in agility, and sport and management routines prior to the injury. Risk factors for injury were evaluated with multivariate logistic regression. The rate of competition-related injuries was 1.44 injuries/1000 competition runs. The front limb was injured in 61% of dogs. In 65% of dogs, the injury presented as lameness. The main risk factors for agility-related injury during 2019 were multiple previous agility-related injuries (OR 11.36; 95% CI 6.10–21.13), older age when starting course-like training (OR 2.04 per one year increase; 95% CI 1.36–3.05), high training frequency, diagnosis of lumbosacral transitional vertebra, and physiotherapy every two to three months compared with never. The most important protective factors were moderate competition frequency and A-frame performance technique. These associations do not confirm causality. We identified new risk factors for injury in agility. This information can be used to improve the welfare of agility dogs.

Prevalences of lumbosacral articulation anatomic variants identified on nuclear scintigraphy and transrectal ultrasonography of Selle Français Warmbloods, French Standardbred Trotters, and Thoroughbreds and agreement between results from the imaging modalities

OBJECTIVE

To describe scintigraphic and transrectal ultrasonographic anatomic variants of the lumbosacral (LS) articulation in horses and to determine the agreement between results obtained with each imaging modality.

ANIMALS

243 horses (81 Selle Français Warmbloods, 81 French Standardbred Trotters, and 81 Thoroughbreds).

PROCEDURES

A retrospective search of clinical records was conducted to identify horses that had undergone nuclear scintigraphy and transrectal ultrasonography of the LS region of the vertebral column between January 2016 and December 2019. Scintigraphic images were evaluated by 2 observers blinded to the other's results for classification of LS articulation anatomic variants (scintigraphic type); intra- and interobserver agreement were determined. Ultrasonographic images were evaluated for classification of LS intervertebral symphysis anatomic variant (ultrasonographic grade) by 1 observer blinded to horses' identities and scintigraphic findings; agreement analysis was performed between scintigraphic type and ultrasonographic grade. Descriptive and statistical analyses were performed to describe distribution of anatomic variants.

RESULTS

The scintigraphic classification system (scintigraphic type) had excellent intra- and interobserver agreement. Agreement between results for scintigraphic type and ultrasonographic grade was moderate (κ = 0.61; 95% CI, 0.52 to 0.70). Anatomic variants of the LS articulation were observed in all groups. The distribution of variants differed significantly among breeds but not sexes.

CLINICAL RELEVANCE

Anatomic variations of the LS articulation in horses must be known to avoid misinterpreting them as clinically meaningful findings. Further research is needed to determine potential relationships between these anatomic variants and LS lesions, their clinical manifestations, and their influence on athletic performance.

Three-Dimensional Kinematics of the Pelvis and Caudal Lumbar Spine in German Shepherd Dogs

Lumbosacral vertebral motion is thought to be a factor in the development of degenerative lumbosacral stenosis in German shepherd dogs. So far, few studies exist describing natural canine lumbosacral movement in vivo. Therefore, this investigation aims to achieve a detailed in vivo analysis of bone movement of the lumbosacral region to gain a better understanding of the origin of degenerative lumbosacral stenosis using three-dimensional non-invasive in vivo analysis of canine pelvic and caudal lumbar motion (at L6 and L7). Biplanar cineradiography of the pelvis and caudal lumbar spine of four clinically sound German shepherd dogs at a walk and at a trot on a treadmill was recorded. Pelvic and intervertebral motion was virtually reconstructed and analyzed with scientific rotoscoping. The use of this technique made possible non-invasive measurement of physiological vertebral motion in dogs with high accuracy. Furthermore, the gait patterns of the dogs revealed a wide variation both between individual steps and between dogs. Pelvic motion showed a common basic pattern throughout the stride cycle. Motion at L6 and L7, except for sagittal rotation at a trot, was largely asynchronous with the stride cycle. Intervertebral motion in all dogs was small with approximately 2–3° rotation and translations of approximately 1–2 mm. The predominant motion of the pelvis was axial rotation at a walk, whereas lateral rotation was predominant at a trot. L7 showed a predominance of sagittal rotation (with up to 5.1° at a trot), whereas lateral rotation was the main component of the movement at L6 (about 2.3° in both gaits). During trotting, a coupling of various motions was detected: axial rotation of L7 and the pelvis was inverse and was coupled with craniocaudal translation of L7. In addition, a certain degree of compensation of abnormal pelvic movements during walking and trotting by the caudal lumbar spine was evident.

The Prevalence of Feline Hip Dysplasia, Patellar Luxation and Lumbosacral Transitional Vertebrae in Pedigree Cats in The Czech Republic

Simple Summary

Hip dysplasia, patellar luxation and lumbosacral transitional vertebra are not well described in cats, most likely because cats can often much better compensate for pelvic limb lameness and hide their pain and, as a result, owners are less likely to notice this condition. Pedigree cats at least 10 months old were recruited prospectively in this study to find the prevalence of feline hip dysplasia, patellar luxation and lumbosacral transitional vertebra. The prevalence of hip joint dysplasia in all pedigree cats was 46.7%, of which 78% of cats had bilateral dysplasia. Dysplasia was mainly from mild (grade 1) to moderate (grade 2); however, 6.1% of hip joints showed signs of severe hip dysplasia (grade 3) in Maine Coon and Siberian cats. Patellar luxation was noted in 32.7% of the pedigree cats, was present bilaterally in 91.4% and was grade 1 or 2 in most cats. The presence of lumbosacral transitional vertebra was noted in 7.5% of the pedigree cats. The high prevalence of hip dysplasia in pedigree cats should be considered and screening pedigree cats for hip dysplasia is recommended before they are used in breeding programs.

Abstract

(1) Background: The aim of this study was to find the prevalence of feline hip dysplasia (HD), patellar luxation and lumbosacral transitional vertebra (LTV) in pedigree cats in the Czech Republic. (2) Methods: 107 pedigree cats at least 10 months old were recruited prospectively at the Small Animal Clinic at the University of Veterinary and Pharmaceutical Sciences Brno, CZ, between April 2019 and July 2020. (3) Results: The prevalence of hip joint dysplasia in all pedigree cats was 46.7%, of which 78% of cats had bilateral dysplasia. The HD was mainly from mild (grade 1) to moderate (grade 2); however, 6.1% of hip joints showed signs of severe HD (grade 3) in Maine Coon and Siberian cats. Patellar luxation was noted in 32.7% of the pedigree cats, was present bilaterally in 91.4% and was grade 1 or 2 in most cats. The presence of LTV was noted in 7.5% of pedigree cats. (4) Conclusions: The high prevalence of HD in pedigree cats should be considered and screening pedigree cats for HD is recommended before they are used in breeding programs.

Genetic background of lumbosacral transitional vertebrae in German shepherd dogs

OBJECTIVES

Estimation of genetic parameters of lumbosacral transitional vertebrae based on data derived from radiographic screening of 27,597 German shepherd dogs.

MATERIALS AND METHODS

Results of radiographic screening for lumbosacral transitional vertebrae classified according to a published scheme were collected. Obtained data were used for estimating variance components in single and multiple trait linear animal models to obtain heritabilities and additive genetic correlations for different types of lumbosacral transitional vertebrae.

RESULTS

Estimations indicated a moderate heritability of lumbosacral transitional vertebrae of h²  = 0.27. Trait definitions reflecting the different types of lumbosacral transitional vertebrae revealed positive additive genetic correlations of r_g  > 0.5 between those types usually categorised as pathologic.

CLINICAL SIGNIFICANCE

Results of comprehensive genetic analyses enable the development of breeding measures against lumbosacral transitional vertebrae to reduce their prevalence and support management of potentially correlated diseases in German shepherd dogs.

Structural anatomy and morphometric analyses of sacra in greyhounds

This study was conducted to provide structural and morphological data on the sacra of greyhounds. Descriptive quantitative investigation was carried out on 171 sacra of greyhound`s cadavers and then classified into standard and fused sacra based on the number of fused sacral vertebrae. The weight, length and width of sacrum of sacra were measured. Both standard (59%) and fused sacra (41%) were identified. The average length and width of the standard sacrum were found to be 46.14 ± 2.53 mm and 57.89 ± 3.54 mm, respectively. The sacral length was 1.61-mm longer in males (p < .01), and the sacral width was 0.46-mm shorter in males but not significant (p = .51). The average weight of a standard sacrum was 26.54 ± 4.55 g and was 1.18 g heavier in males but not statistically significant (p = .24). Results showed that one-kilogram increase in the body mass was associated with a 0.3 mm (p < .001) increase in sacral length, and a 0.54 mm (p < .001) increase in sacral width, respectively. The morphological data of the standard and fused sacra provided in this study might help the veterinary community to improve treatment and rehabilitation and help the trainer to design the right training protocol for racing greyhounds. In addition, the results of this study are a step to understand the sacrum's functions and how the greyhound's body functions and future studies are required to investigate the biological importance of these findings.

Radiographic evaluation of congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis)

Background

The normal vertebral anatomy of Korean raccoon dogs and their variants require research attention as a prerequisite for identifying pathologies and anomalies.

Objectives

This retrospective study aimed at describing the vertebral formula and congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis).

Methods

Radiographs of 82 raccoon dogs (42 males, 40 females) acquired from May 2013 to June 2020 in the Gangwon Wildlife Medical Rescue Center were reviewed to evaluate the cervical, thoracic, and lumbar vertebrae of the spine.

Results

Normal morphology of all vertebrae was observed in 50 of the 82 raccoon dogs, and the vertebral formula was cervical 7, thoracic 13, and lumbar 7. Congenital vertebral anomalies were found in 32 raccoon dogs: transitional vertebrae (TV) in 31 and block vertebrae in 2. Two raccoon dogs had 2 types of vertebral anomalies: one had TV and block vertebra, and the other had 2 types of TV. Twenty-nine raccoon dogs had thoracolumbar TV (TTV) and 3 had lumbosacral TV. TTV was morphologically classified into 4 different types: unilateral extra-rib in 5 raccoon dogs, bilateral extra-ribs in 14, bilateral elongated transverse processes in 4, and an asymmetric mixed formation of extra-rib with elongated transverse process in 6.

Conclusions

This study showed that TTV is common in Korean raccoon dogs, and that the vertebral formula is relatively diverse. The bilateral extra-ribs type TTV is the most common variant, which is almost similar to normal rib to be confused the radiographic evaluation.

Radiographic lumbosacral vertebral abnormalities and constipation in cats

Background and Aim:

Lumbosacral intervertebral disk disease (IVDD) in cats usually develops concurrent with constipation, spondylosis deformans, and sacralization. However, the prevalence of lumbar IVDD in cats was considered low, and there was less information on the incidence of non-traumatic lumbosacral vertebral abnormalities that may affect large bowel dysfunction. This study aimed to retrospectively investigate the relationship between non-traumatic lumbosacral vertebral abnormalities, both congenital and acquired, and large bowel dysfunction in cats.

Materials and Methods:

Of 3108 cats that were presented to the Diagnostic Imaging Unit, the Small Animal Teaching Hospital, Faculty of Veterinary Science, Chulalongkorn University, between March 2016 and February 2018, 1365 cats met the inclusion criteria. All abdominal radiographs were reviewed, and all subsequent data were recorded, including the presence of congenital or acquired lumbosacral lesions, number of lumbar vertebrae, and length of the second, fifth, and last lumbar vertebrae, including the type of lumbar abnormalities. Moreover, radiographic information relating to constipation and megacolon was also collected.

Results:

Non-traumatic lumbosacral vertebral abnormalities were observed in 29.74% of cats. The most common congenital lumbosacral vertebral abnormalities were six lumbar vertebrae, sacralization, and lumbarization, whereas most common acquired lumbosacral abnormalities were bone spur, narrowing disk space, spondylosis deformans, and lumbosacral degeneration, respectively. Cats with abnormal lumbosacral vertebrae are prone to have more problems with the large bowel (p=0.0057; odds ratio=1.731). Moreover, congenital and acquired lumbosacral abnormalities were also at risk of large bowel abnormalities (p=0.0069; odds ratio=1.920 and p<0.0001; odds ratio=4.107, respectively).

Conclusion:

This study revealed the evidence and distribution of the variation in feline lumbar anatomy and also elucidated that cats with abnormal lumbar vertebral columns were more likely to have problems with distal gastrointestinal tracts than those without.

Influence of a customized three-dimensionally printed drill guide on the accuracy of pedicle screw placement in lumbosacral vertebrae: An ex vivo study

OBJECTIVE

To compare the accuracy of pedicle screw insertion (PSI) into canine lumbosacral vertebrae with custom-made three-dimensionally (3D)-printed drill guides or freehand insertion.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Nineteen canine lumbosacral specimens.

METHODS

Drill guides for PSI were designed on the basis of safe screw insertion trajectories by using preoperative computed tomography (CT) and produced by 3D printing of templates. Right and left sides of the specimens were randomly allocated to two groups; 4-mm pedicle screws were inserted in L5-L6 and L7-S1 spinal segments either freehand (control group) or with custom-made drill guides (guide group). Sixty-six screws were inserted with each method. Insertion angles (α, β), bone stock, and vertebral canal breach were assessed according to postoperative CT. χ² Tests were used to compare vertebral canal breach between groups and vertebrae.

RESULTS

Breaches in the vertebral canal were less common (P < .001) when screws were placed with a guide in the guide group (9/66, 14%) than without a guide (30/66, 45%). The rate of vertebral canal breach differed at L5 (P = .021) but not at L6 (P = .05), L7 (P = .075) or S1 (P = .658). The angle of insertion (α) did not differ between specimens with and without breaches (guide, P = .068; control, P = .394).

CONCLUSION

The use of a customized 3D-printed guide generally improved the accuracy of PSI in canine lumbosacral vertebrae, although statistical significance was reached only at L5.

CLINICAL SIGNIFICANCE

The use of customized drill guides may be considered as an alternative to freehand PSI in the lumbosacral area, especially for L5-L6 vertebrae.

Retrospective analysis of diagnoses and outcomes of 45 cats with micturition disorders presenting as urinary incontinence

Background

In contrast to dogs, the causes and outcomes of urinary incontinence (UI) in cats are largely unknown.

Objectives

To determine the causes, identify comorbid conditions, and assess outcomes of cats with micturition disorders presenting as UI.

Animals

Forty‐five cats with UI.

Methods

Retrospective study. Medical records of cats presented from January 2006 to December 2017 were searched using 45 keywords related to UI. History, presenting complaint, and physical examination findings were used to confirm a diagnosis. Cases were categorized based on functional and anatomic localizations.

Results

Forty‐five cats met inclusion criteria. Spinal cord disease was the most common cause of UI (n = 18), followed by urethral (n = 17), bladder (n = 9), and ureteral (n = 1) disorders. Proportions of voiding and storage phase disorders were similar (53% and 47%, respectively). However, voiding‐phase disorders were observed more frequently in males and younger‐aged cats (P < .03). Urinary tract infection was detected in 11 of 28 (39%) cats. Outcomes were available in 38/45 cases; 16 cats (42%) regained continence, 3 (8%) improved with treatment, and 19 (50%) remained incontinent or were euthanized. Multiple variable logistic regressions indicated that spinal cord disease was significantly more likely to be associated with poor outcomes compared to bladder or urethral disorders (P < .04).

Conclusions and Clinical Importance

Urinary incontinence in cats was associated with a variety of congenital and acquired disorders that affected both phases of micturition with similar frequency. Incontinent cats with spinal cord disorders were common and warrant a more guarded prognosis than do cats with bladder or urethral disorders.

Giant extinct caiman breaks constraint on the axial skeleton of extant crocodylians

The number of precaudal vertebrae in all extant crocodylians is remarkably conservative, with nine cervicals, 15 dorsals and two sacrals, a pattern present also in their closest extinct relatives. The consistent vertebral count indicates a tight control of axial patterning by Hox genes during development. Here we report on a deviation from this pattern based on an associated skeleton of the giant caimanine Purussaurus, a member of crown Crocodylia, and several other specimens from the Neogene of the northern neotropics. P. mirandai is the first crown-crocodylian to have three sacrals, two true sacral vertebrae and one non-pathological and functional dorsosacral, to articulate with the ilium (pelvis). The giant body size of this caiman relates to locomotory and postural changes. The iliosacral configuration, a more vertically oriented pectoral girdle, and low torsion of the femoral head relative to the condyles are hypothesized specializations for more upright limb orientation or weight support.

Canine Degenerative Lumbosacral Stenosis: Prevalence, Impact And Management Strategies

Canine degenerative lumbosacral stenosis (DLSS) is a syndrome of low back pain with or without neurologic dysfunction associated with compression of the cauda equina. Most commonly occurring in medium- to large-breed dogs of middle to older age, German shepherd and working dogs are predisposed. Diagnosis is based on a combination of clinical signs, advanced imaging and ruling out other differential diagnoses. The volume of the intervertebral foramina at the lumbosacral junction is naturally reduced on extension but degenerative changes lead to a more marked reduction that can impinge the L7 nerve roots. Evidence is lacking on which to base decision-making for treatment of dogs with DLSS. However, surgical intervention may be indicated in dogs that do not respond to conservative management, or for dogs in which there is a requirement to work that prevents lifestyle adjustments. Improvements in electrodiagnosis and novel intra-discal treatments may improve the management of DLSS in the future.

Congenital malformations of the lumbosacral vertebral column are common in neurologically normal French Bulldogs, English Bulldogs, and Pugs, with breed-specific differences

Congenital vertebral malformations are common findings on diagnostic imaging of the vertebral column in "screw-tailed" brachycephalic dogs. The aims of this study were to evaluate the prevalence and anatomical characteristics of lumbosacral congenital vertebral malformations in French Bulldogs, English Bulldogs, and Pugs presenting for problems unrelated to spinal disease, as well as possible associations with the degree of tail malformation, lumbosacral intervertebral disc herniation, or spondylosis deformans. In this retrospective cross-sectional study, CT scans of vertebrae L6 to S3 and of the coccygeal vertebrae were reviewed for type of congenital vertebral malformations (hemivertebrae, block vertebrae, lumbosacral transitional vertebrae, and spina bifida), lumbosacral intervertebral disc herniation, lumbosacral spondylosis deformans, and degree of tail malformation. In 76 (51.0%) of the 149 included dogs (53 French Bulldogs, 37 English Bulldogs, and 59 Pugs) at least one type of congenital vertebral malformations was found, with lumbosacral transitional vertebrae being the most common (34.2%). There was a significantly higher prevalence of lumbosacral transitional vertebrae (54.2%) and lower prevalence of hemivertebrae (1.7%) in Pugs compared to English (13.5% and 24.3%, respectively) and French Bulldogs (26.4% and 32.0%, respectively). Tail malformation was significantly more severe in dogs with evidence of hemivertebrae. Congenital vertebral malformations are a common finding in the lumbosacral vertebral column of French Bulldogs, English Bulldogs, and Pugs. These anatomical variances need to be considered when interpreting diagnostic studies and when planning for neurosurgical and neurodiagnostic procedures. Furthermore, this study suggests a possible association between the degree of tail malformation and lumbosacral hemivertebrae.

Genomic signatures of extensive inbreeding in Isle Royale wolves, a population on the threshold of extinction

The observation that small isolated populations often suffer reduced fitness from inbreeding depression has guided conservation theory and practice for decades. However, investigating the genome-wide dynamics associated with inbreeding depression in natural populations is only now feasible with relatively inexpensive sequencing technology and annotated reference genomes. To characterize the genome-wide effects of intense inbreeding and isolation, we performed whole-genome sequencing and morphological analysis of an iconic inbred population, the gray wolves (Canis lupus) of Isle Royale. Through population genetic simulations and comparison with wolf genomes from a variety of demographic histories, we find evidence that severe inbreeding depression in this population is due to increased homozygosity of strongly deleterious recessive mutations. Our results have particular relevance in light of the recent translocation of wolves from the mainland to Isle Royale, as well as broader implications for management of genetic variation in the fragmented landscape of the modern world.

Lumbosacral transitional vertebrae in cats and its relationship to lumbosacral vertebral canal stenosis

OBJECTIVES

Although a clear relationship has been demonstrated between the presence of lumbosacral transitional vertebrae and the development of lumbosacral stenosis in dogs, this relationship has not been evaluated in cats. The aim of this study was to investigate the relationship between the presence of lumbosacral transitional vertebrae and lumbosacral stenosis in cats.

METHODS

The medical records and diagnostic imaging studies of 13 cats diagnosed with lumbosacral stenosis were retrospectively reviewed for lumbosacral abnormalities and compared with findings of 405 cats that underwent CT for reasons unrelated to spinal disease.

RESULTS

Clinical signs associated with lumbosacral stenosis included lumbosacral pain, low tail carriage, difficulty jumping, and urinary or faecal incontinence. Neurological signs included proprioceptive deficits, ambulatory paraparesis, pelvic limb ataxia, reduced spinal reflexes and reduced perianal reflex. Duration of clinical signs ranged from 1 day to 10 months (mean 3 months). Of the 13 cats with lumbosacral stenosis, seven (53.8%) were diagnosed with lumbosacral transitional vertebrae. In the control population of 405 cats, 24 (5.9%) were diagnosed with lumbosacral transitional vertebrae. Results indicated that lumbosacral transitional vertebrae were significantly ( P <0.0001) more prevalent in cats with lumbosacral stenosis compared with the control feline population (odds ratio 18.52, 95% confidence interval 6.1-62.1). Development of clinical signs of lumbosacral stenosis in cats with lumbosacral transitional vertebrae (mean 10.8 years) was not significantly different from that of cats without lumbosacral transitional vertebrae (mean 12.7 years). Likewise, there was no significant influence of breed ( P >0.99) or sex ( P = 0.29) on the occurrence of lumbosacral transitional vertebrae.

CONCLUSIONS AND RELEVANCE

Despite lumbosacral stenosis being a rare spinal condition in cats, lumbosacral transitional vertebrae can be considered a risk factor for its development.

Cauda equina syndrome in dogs - a review

A lesion of sacrococcygeal spinal nerve roots forming a structure that resembles a horse's tail results in the development of clinical entity identified as the cauda equina syndrome (CES). The disease can evolve slowly and symptomatology can be incomplete, but the fully developed CES is characterized by pain and altered sensation in the pelvic extremities, tail, perianogenital region, paresis or plegia of hind limbs, incontinence and impotence. Major causes of CES in dogs are degenerative changes of the lumbosacral vertebral column, haematoma, inflammation, neoplasm or trauma. The diagnosis is based on history, clinical presentation, neurological symptomatology, spinal röntgenography, computed tomography, and magnetic resonance imaging. In animals experiencing initial episodes of CES, conservative therapy can be attempted. But the only rational treatment of patients with severe neurological deficit is surgical decompression of the neural structures. The outcome depends on the underlying aetiology and the degree of sensory, motor and autonomic dysfunction. Canine and porcine experimental models mimicking the CES showed the involvement of intrinsic spinal cord structures. This points out the need for an early diagnosis followed by aggressive management before irreversible neuronal lesions develop. The search strategy involved the PubMed, Medline, Embase and ISI Web of Science from January 2000 to August 2017 using the terms 'cauda equina syndrome' and 'lumbosacral stenosis' in the English language literature; also references from selected papers were scanned and relevant articles included.

C7 vertebra homeotic transformation in domestic dogs - are Pug dogs breaking mammalian evolutionary constraints?

The number of cervical vertebrae in mammals is almost constant at seven, regardless of their neck length, implying that there is selection against variation in this number. Homebox (Hox) genes are involved in this evolutionary mammalian conservation, and homeotic transformation of cervical into thoracic vertebrae (cervical ribs) is a common phenotypic abnormality when Hox gene expression is altered. This relatively benign phenotypic change can be associated with fatal traits in humans. Mutations in genes upstream of Hox, inbreeding and stressors during organogenesis can also cause cervical ribs. The aim of this study was to describe the prevalence of cervical ribs in a large group of domestic dogs of different breeds, and explore a possible relation with other congenital vertebral malformations (CVMs) in the breed with the highest prevalence of cervical ribs. By phenotyping we hoped to give clues as to the underlying genetic causes. Twenty computed tomography studies from at least two breeds belonging to each of the nine groups recognized by the Federation Cynologique Internationale, including all the brachycephalic 'screw-tailed' breeds that are known to be overrepresented for CVMs, were reviewed. The Pug dog was more affected by cervical ribs than any other breed (46%; P < 0.001), and was selected for further analysis. No association was found between the presence of cervical ribs and vertebral body formation defect, bifid spinous process, caudal articular process hypoplasia/aplasia and an abnormal sacrum, which may infer they have a different aetiopathogenesis. However, Pug dogs with cervical ribs were more likely to have a transitional thoraco-lumbar vertebra (P = 0.041) and a pre-sacral vertebral count of 26 (P < 0.001). Higher C7/T1 dorsal spinous processes ratios were associated with the presence of cervical ribs (P < 0.001), supporting this is a true homeotic transformation. Relaxation of the stabilizing selection has likely occurred, and the Pug dog appears to be a good naturally occurring model to further investigate the aetiology of cervical ribs, other congenital vertebral anomalies and numerical alterations.

Lumbosacral stenosis in Labrador retriever military working dogs - an exomic exploratory study

Background

Canine lumbosacral stenosis is defined as narrowing of the caudal lumbar and/or sacral vertebral canal. A risk factor for neurologic problems in many large sized breeds, lumbosacral stenosis can also cause early retirement in Labrador retriever military working dogs. Though vital for conservative management of the condition, early detection is complicated by the ambiguous nature of clinical signs of lumbosacral stenosis in stoic and high-drive Labrador retriever military working dogs. Though clinical diagnoses of lumbosacral stenosis using CT imaging are standard, they are usually not performed unless dogs present with clinical symptoms. Understanding the underlying genomic mechanisms would be beneficial in developing early detection methods for lumbosacral stenosis, which could prevent premature retirement in working dogs. The exomes of 8 young Labrador retriever military working dogs (4 affected and 4 unaffected by lumbosacral stenosis, phenotypically selected by CT image analyses from 40 dogs with no reported clinical signs of the condition) were sequenced to identify and annotate exonic variants between dogs negative and positive for lumbosacral stenosis.

Results

Two-hundred and fifty-two variants were detected to be homozygous for the wild allele and either homozygous or heterozygous for the variant allele. Seventeen non-disruptive variants were detected that could affect protein effectiveness in 7 annotated (SCN1B, RGS9BP, ASXL3, TTR, LRRC16B, PTPRO, ZBBX) and 3 predicted genes (EEF1A1, DNAJA1, ZFX). No exonic variants were detected in any of the canine orthologues for human lumbar spinal stenosis candidate genes.

Conclusions

TTR (transthyretin) gene could be a possible candidate for lumbosacral stenosis in Labrador retrievers based on previous human studies that have reported an association between human lumbar spinal stenosis and transthyretin protein amyloidosis. Other genes identified with exonic variants in this study but with no known published association with lumbosacral stenosis and/or lumbar spinal stenosis could also be candidate genes for future canine lumbosacral stenosis studies but their roles remain currently unknown. Human lumbar spinal stenosis candidate genes also cannot be ruled out as lumbosacral stenosis candidate genes. More definitive genetic investigations of this condition are needed before any genetic test for lumbosacral stenosis in Labrador retriever can be developed.

Electronic supplementary material

The online version of this article (10.1186/s40575-017-0052-6) contains supplementary material, which is available to authorized users.

ACCURACY OF RADIOGRAPHIC DETECTION OF THE CRANIAL MARGIN OF THE DORSAL LAMINA OF THE CANINE SACRUM

An elongated sacral lamina has been described as one of the contributing factors for dogs with cauda equina syndrome due to degenerative lumbosacral stenosis (DLSS); however, published evidence is lacking on the accuracy of radiographic screening for the presence of this lesion. Objectives of this prospective, cross-sectional cadaver study were to describe the accuracy and repeatability of detection of the cranial sacral lamina margin on plain lateral radiographs of the lumbosacral junction in dogs. Twenty-five medium and large breed canine cadavers were radiographed before and after placement of a radiopaque hook in the cranial margin of the sacral lamina. Three independent evaluators placed digital markers at the perceived margin on preinterventional radiographs. The distance from perceived location to the true location on postinterventional radiographs was recorded for each dog and observer. A discordance threshold (distance between perceived and actual margin) of 1.5 mm was subjectively defined as clinically relevant. The three evaluators demonstrated good repeatability, although the accuracy for margin detection was only fair (mean discordance 1.7 mm). Evaluators demonstrated greater accuracy in identifying the landmark in juveniles (1.4 mm) vs. adults (1.8 mm; P < 0.01). Results of this study indicated that observer repeatability is good and accuracy is fair for correctly identifying the radiographic cranial margin of the sacral lamina in dogs. This should be taken into consideration when interpreting elongation of the sacral lamina in radiographs of dogs with suspected DLSS, especially adults.

Prevalence of lumbosacral transitional vertebrae in dogs in the Czech Republic

Lumbosacral transitional vertebra is a common congenital anomaly of the spine in dogs. It is a predisposing factor for degeneration of the lumbosacral spine and development of cauda equina syndrome or hip dysplasia in affected dogs. The aim of the study was to determine breed predisposition, types, and prevalence of lumbosacral transitional vertebrae in the canine population in the Czech Republic. The value of laterolateral radiographs of the lumbosacral junction in the diagnosis of LTV was also evaluated. Prevalence of lumbosacral transitional vertebrae was determined by reviewing ventrodorsal radiographs of pelvis with an extended hip of 1,878 dogs. Lumbosacral transitional vertebrae were detected in 188 dogs (10%). German Shepherd, Alaskan Malamute and Bohemian Shepherd were found to be highly predisposed breeds. The most common type of lumbosacral transitional vertebra was type II with separation of the first sacral vertebra from sacrum and presence of rudimentary intervertebral space between S1 and the sacral median crest (37.8% of the lumbosacral transitional vertebrae). Type I was detected in 29.2% and the asymmetric type of the lumbosacral transitional vertebra (type III) in 33%. Laterolateral radiograph of the lumbosacral spine was evaluated in 126 dogs from 188 with lumbosacral transitional vertebrae. Rudimentary intervertebral disc space between S1 and S2 in laterolateral radiographs was detected in 100% of lumbosacral transitional vertebrae with type II and III, and was not detected in type I. The findings on lumbosacral transitional vertebrae in the Czech Republic will extend knowledge about the disease. Both ventrodorsal hip-extended and laterolateral radiographs should be recommended for routine screening and reliable differentiation among the three different types of lumbosacral transitional vertebra.

Congenital abnormalities of the vertebral column in ferrets

Vertebral column pathologies requiring surgical intervention have been described in pet ferrets, however little information is available on the normal vertebral formula and congenital variants in this species. The purpose of this retrospective study was to describe vertebral formulas and prevalence of congenital vertebral anomalies in a sample of pet ferrets. Radiographs of 172 pet ferrets (96 males and 76 females) were included in this retrospective study. In 143 ferrets (83.14%), five different formulas of the vertebral column were recorded with normal morphology of vertebrae (rib attachment included) but with a variable number of thoracic (Th), lumbar (L), and sacral (S) vertebrae. The number of cervical (C) vertebrae was constant in all examined animals. Observed vertebral formulas were C7/Th14/L6/S3 (51.74%), C7/Th14/L6/S4 (22.10%), C7/Th14/L7/S3 (6.98%), C7/Th15/L6/S3 (1.74%), and C7/Th15/L6/S4 (0.58%). Formula C7/Th14/L6/S4 was significantly more common in males than in females (P < 0.05). Congenital spinal abnormalities were found in 29 ferrets (16.86%), mostly localized in the thoracolumbar and lumbosacral regions. The cervical region was affected in only one case. Transitional vertebrae represented the most common congenital abnormalities (26 ferrets) in the thoracolumbar (13 ferrets) and lumbosacral regions (10 ferrets) or simultaneously in both regions (three ferrets). Other vertebral anomalies included block (two ferrets) and wedge vertebra (one ferret). Spina bifida was not detected. Findings from the current study indicated that vertebral formulas may vary in ferrets and congenital abnormalities are common. This should be taken into consideration for surgical planning.

What the Inbred Scandinavian Wolf Population Tells Us about the Nature of Conservation

The genetic aspects of population health are critical, but frequently difficult to assess. Of concern has been the genetic constitution of Scandinavian wolves (Canis lupus), which represent an important case in conservation. We examined the incidence of different congenital anomalies for 171 Scandinavian wolves, including the immigrant founder female, born during a 32-year period between 1978 and 2010. The incidence of anomalies rose from 13% to 40% throughout the 32-year study period. Our ability to detect this increase was likely facilitated by having considered multiple kinds of anomaly. Many of the found anomalies are likely associated with inbreeding or some form of genetic deterioration. These observations have implications for understanding the conservation needs of Scandinavian wolves. Moreover, these observations and the history of managing Scandinavian wolves focus attention on a broader question, whether conservation is merely about avoiding extinction of remnant populations, or whether conservation also entails maintaining genetic aspects of population health.

Evo-Devo of the Human Vertebral Column: On Homeotic Transformations, Pathologies and Prenatal Selection

Homeotic transformations of vertebrae are particularly common in humans and tend to come associated with malformations in a wide variety of organ systems. In a dataset of 1,389 deceased human foetuses and infants a majority had cervical ribs and approximately half of these individuals also had missing twelfth ribs or lumbar ribs. In ~10 % of all cases there was an additional shift of the lumbo-sacral boundary and, hence, homeotic transformations resulted in shifts of at least three vertebral boundaries. We found a strong coupling between the abnormality of the vertebral patterns and the amount and strength of associated malformations, i.e., the longer the disturbance of the vertebral patterning has lasted, the more associated malformations have developed and the more organ systems are affected. The germ layer of origin of the malformations was not significantly associated with the frequency of vertebral patterns. In contrast, we find significant associations with the different developmental mechanisms that are involved in the causation of the malformations, that is, segmentation, neural crest development, left-right patterning, etc. Our results, thus, suggest that locally perceived developmental signals are more important for the developmental outcome than the origin of the cells. The low robustness of vertebral A-P patterning apparent from the large number of homeotic transformations is probably caused by the strong interactivity of developmental processes and the low redundancy of involved morphogens during early organogenesis. Additionally, the early irreversibility of the specification of the A-P identity of vertebrae probably adds to the vulnerability of the process by limiting the possibility for recovery from developmental disturbances. The low developmental robustness of vertebral A-P patterning contrasts with a high robustness of the A-P patterning of the vertebral regions. Not only the order is invariable, also the variation in the number of vertebrae per region is small. This robustness is in agreement with the evolutionary stability of vertebral regions in tetrapods. Finally, we propose a new hypothesis regarding the constancy of the presacral number of vertebrae in mammals.

Alternative classification and screening protocol for transitional lumbosacral vertebra in German shepherd dogs

Background

Lumbosacral transitional vertebra (LTV) is a common congenital and hereditary anomaly in many dog breeds. It predisposes to premature degeneration of the lumbosacral junction, and is a frequent cause of cauda equina syndrome, especially in German shepherd dogs. Ventrodorsal hip radiographs are most often used in diagnosis of LTV in screening programs. In this study, value of laterolateral lumbar spine radiographs as additions to ventrodorsal radiographs in diagnosis of LTV, and characteristics of LTV and the eighth lumbar vertebra (L8) in laterolateral radiographs were studied. Additionally, computed tomography (CT) features of different types of LTV were elucidated.

Methods

The ventrodorsal pelvic and laterolateral lumbar spine radiographs of 228 German shepherd dogs were evaluated for existence and type of LTV. Morphology of transverse processes was used in classification of LTV in ventrodorsal radiographs. The relative length of sixth (L6) and seventh (L7) vertebrae (L6/L7) was used in characterization of these vertebrae in laterolateral radiographs. CT studies were available for 16 dogs, and they were used for more detailed characterization of different types of LTV. Non-parametric χ² statistics, generalized logit model for multinomial data, and one-way analysis of variance was used for statistical analyses.

Results

In all, 92 (40%) dogs had a LTV, the most common type being separation of first spinous process from the median crest of the sacrum in 62 dogs (67% of LTV). Eight dogs had eight lumbar vertebrae. Those dogs with LTV had longer L7 in relation to L6 than dogs with normal lumbosacral junctions. When L6/L7 decreased by 0.1 units, the proportion of dogs belonging to the group with L8 was 14-fold higher than in the group with normal lumbosacral junctions. L8 resembled first sacral vertebra (S1) in length and position and was therefore classified as one type of LTV. With CT it was shown that categorizing LTV, based on shape and visibility of transverse processes seen in ventrodorsal radiographs, could be misleading.

Conclusions

We suggest that L8 be included as a part of the LTV complex, and the laterolateral radiographs of the lumbar spine be considered as an addition to ventrodorsal projections in the screening protocols for LTV.

Lumbosacral transitional vertebrae in cats and their effects on morphology of adjacent joints

The present study aimed to describe the radiographic appearance of lumbosacral transitional vertebrae in the cat and compare prevalence of hip dysplasia and lumbosacral spondylosis with a population of cats without transitional vertebrae. Pelvic radiographs of cats were reviewed retrospectively, providing a population of 100 cats without transitional vertebrae and 14 examples of lumbosacral transitional vertebrae. All cats were assessed for hip dysplasia and lumbosacral spondylosis; the lumbosacral transitional vertebrae identified were also assessed for asymmetry or rotation of sacro-iliac (SI) attachment. The transitional vertebrae demonstrated a wide variety of morphology; six cats had asymmetry or rotation of SI attachment in a dorsal plane; four of those six cats had lumbosacral spondylosis and two of these had hip dysplasia. No further examples of degenerative changes were identified in the remaining eight cats with lumbosacral transitional vertebrae. The frequency of lumbosacral spondylosis was higher in the population with lumbosacral transitional vertebrae, but this was not statistically significant. There was a marked trend towards lumbosacral spondylosis in cats with pelvic rotation or asymmetry. The frequency of hip dysplasia in cats with lumbosacral transitional vertebrae was very similar to those without.

Congenital abnormalities of the feline vertebral column

Radiographs of vertebral segments from 200 cats were retrospectively assessed to determine the incidence of congenital axial skeletal abnormalities. The axial skeleton was divided into cervical, thoracic, lumbar, sacral, and caudal segments and the presence and types of congenital abnormalities present were recorded for each segment. A total of 598 axial skeletal segments were examined. Congenital abnormalities were found in 46 cats and involved 54 spinal segments. Block vertebrae were identified in three cats. No hemivertebrae or spina bifida were noted. Transitional abnormalities were most common, and were identified in 51 spinal segments. Abnormalities at the sacrocaudal junction were the most common of these; 19 examples were found. The second most common transitional abnormality was thoracicization of L1, with 18 such cats identified. Extra ribs on L1 were often smaller and fragmented and it may be possible for an inexperienced clinician to confuse these with rib fractures. The last rib(s) are also often used for anatomic localization of surgical procedures; the presence of a transitional lumbar vertebra with one or two extra ribs introduces the possibility of error or confusion about choice of surgical site.