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.

Surgical treatment and outcome of haematomyelia with a traumatic cause in a dog and a cat.

Two surgically treated haematomyelia cases were documented. One dog and one cat were presented for acute progressive paraplegia following a fall from height incident. Neurological examinations suggested a L4-S3 myelopathy in both cases. Radiography and magnetic resonance imaging in both cases revealed no fracture or subluxation of the spine, but well-defined intramedullary mass lesions in lower lumbar regions compatible with haemorrhage and haematoma formation. Exploratory surgeries were performed over the lesions. Dark-red friable masses were removed via myelotomy. Histopathological examinations revealed organizing haematomas at the acute to subacute stage. Postoperatively, both cases improved and regained ambulation. The dog walked normally but remained urinary and faecal incontinent 9 months after the surgery. The cat was continent and ambulatory with a paraparetic gait 5 months after the surgery. In both cases, the outcomes and the patients' quality of life were considered satisfactory by the owners.

Intraobserver and interobserver agreement of 8 segmental reflexes in healthy dogs.

BACKGROUND: No available literature supports the claim that the patellar and withdrawal (flexor) reflexes are the only reliable segmental reflexes in dogs. OBJECTIVE: Measure intra- and interobserver agreement of 8 segmental reflexes in dogs without clinical evidence of orthopedic or neurologic disease. ANIMALS: One-hundred and one client- or staff-owned dogs between 1 and 10 years of age with no clinical evidence of orthopedic disease, myelopathy, or neuromuscular disease. METHODS: Descriptive study. The intraobserver proportion of agreement (%) of responses to selected segmental reflexes in right versus left limbs by 3 observers was calculated and reported. The interobserver agreement of 2 observers of responses to selected reflexes was estimated by calculating proportions of agreement, kappa values, and 95% confidence intervals. A segmental reflex with an acceptable agreement was defined as that with a proportion of agreement ≥90% and a Kappa value ≥0.61 in both limbs. RESULTS: The intraobserver proportion of agreement for all 3 observers was high (≥95%) for the extensor carpi radialis, withdrawal, patellar, and cranial tibial reflexes. Between observers 1 and 3 and observers 2 and 3, the interobserver proportion of agreement was high (≥ 92%) for the extensor carpi radialis (κ 0.66, not determined [ND]), withdrawal (both limbs, κ ND), patellar (κ ND), and cranial tibial reflexes (κ ND). CONCLUSIONS AND CLINICAL IMPORTANCE: The extensor carpi radialis, withdrawal, patellar, and cranial tibial reflexes had a higher proportion of agreement and kappa values between 2 observers.

Vertebral Angiomatosis in a Dog.

A 3 yr old spayed female Cavalier King Charles spaniel was referred for insidious ataxia and paraparesis. A thoracolumbar lesion was suspected. Computed tomography showed focal osteolysis of the vertebral body and pedicles of T5. In addition, a hyperdense, extradural material within the vertebral canal, causing spinal cord compression on the right side, was present. The lesion was confirmed with magnetic resonance imaging. A T4-T5 hemi-dorsal laminectomy was performed to decompress the spinal cord. Histopathological examination was consistent with vertebral angiomatosis. After the surgery, the dog rapidly improved; however, 5 mo later the clinical signs relapsed. Vertebral angiomatosis is a vasoproliferative disorder, rarely reported as a cause of myelopathy in cats. This condition has not previously been reported in dogs. This case report describes the clinical features, the diagnostic findings, and the follow-up of a young dog with vertebral angiomatosis.

Allele and genotype frequencies for primary hereditary cataract, multifocal retinopathy 1, and degenerative myelopathy in Pyrenean Mountain dog from Italy.

Pyrenean Mountain Dog (PMD) is an ancient dog breed firstly described in XIV century in the Pyrenees Region and nowadays diffused both in Europe and in the US. Hereditary Cataract (HC), defined as the inherited opacity of the lens, involves clinical signs ranging from reduced vision to glaucoma. A molecular basis of HC was firstly described in Staffordshire Bull Terriers and then reported in multiple canine breeds. The HC-associated variation is a single nucleotide deletion in HSF4 gene that introduces a premature stop codon (c.962del, p.Ala321*). Multifocal Retinopathy 1 (MR) is an ocular disorder characterized by multiple areas of retinal degeneration, caused in various dog breeds (including PMD) by a single nucleotide variant (SNV) in BEST1 gene that generates a premature stop codon (c.73G>A, p.Arg25*). Degenerative Myelopathy (DM) is an adult-onset, progressive neurodegenerative disease and it is associated to a SNV in SOD1 gene causing a change in aminoacidic sequence of the protein (c.118G>A, p.Glu40Lys). This causative variant has been described in various dog breeds, including PMD. Aim of this study was to determine the allele frequencies for the abovementioned three genetic diseases in the Italian breeding PMD population. The survey found no dogs carrying the allele (deletion) associated with HC, while three dogs (6 %) were heterozygous (G/A) for the MR-associated variant, and seven dogs (13 %) were heterozygous (G/A) for the DM-associated alteration, indicating that the variant alleles frequency were 0  %, 3 %, and 7 %, respectively. Appropriate mating management is suggested for the prevention of genetic diseases spreading in the PMD population.

Association of the FGF4L2 retrogene with fibrocartilaginous embolic myelopathy in dogs.

BACKGROUND: Fibrocartilaginous embolic myelopathy (FCE) is a well-documented condition in dogs although rarely reported in chondrodystrophic breeds. Genetic associations have not been defined. OBJECTIVES: Define the association of the chondrodystrophy-associated FGF4L2 retrogene with histopathologically confirmed cases of FCE. ANIMALS: Ninety-eight dogs with a histopathologic diagnosis of FCE. METHODS: Retrospective multicenter study. Dogs were genotyped for the FGF4L2 and FGF4L1 retrogenes using DNA extracted from formalin-fixed, paraffin-embedded tissue. Associations between breed, FCE and retrogene status were investigated with reference to a hospital population and known breed and general population allele frequencies. RESULTS: FGF4L2 genotype was defined in 89 FCE cases. Fibrocartilaginous embolic myelopathy was present in 22 dogs from FGF4L2-segregating breeds with allele frequencies of ≥5%; however, all dogs were wild type. Two Labrador retrievers with FCE carried FGF4L2 alleles. Frequency of the FGF4L2 allele was significantly (P < .001) and negatively associated with FCE relative to predicted hospital-population dogs. FCE was overrepresented in Boxer, Great Dane, Yorkshire Terrier, Bernese Mountain Dog, Miniature Schnauzer, Rottweiler, and Shetland Sheepdog breeds. CONCLUSIONS AND CLINICAL IMPORTANCE: Study data based on genotypically and histopathologically defined cases support the historical observation that FCE is uncommon in chondrodystrophic dog breeds. FGF4 plays an important role in angiogenesis and vascular integrity; anatomical studies comparing chondrodystrophic and non-chondrodystrophic dogs might provide insight into the pathogenesis of FCE.

Negative Selection on a SOD1 Mutation Limits Canine Degenerative Myelopathy While Avoiding Inbreeding.

Several hundred disease-causing mutations are currently known in domestic dogs. Breeding management is therefore required to minimize their spread. Recently, genetic methods such as direct-to-consumer testing have gained popularity; however, their effects on dog populations are unclear. Here, we aimed to evaluate the influence of genetic testing on the frequency of mutations responsible for canine degenerative myelopathy and assess the changes in the genetic structure of a Pembroke Welsh corgi population from Japan. Genetic testing of 5,512 dogs for the causative mutation in superoxide dismutase 1 (SOD1) (c.118G>A (p.E40K)) uncovered a recent decrease in frequency, plummeting from 14.5% (95/657) in 2019 to 2.9% (24/820) in 2022. Weir and Cockerham population differentiation (FST) based on genome-wide single-nucleotide polymorphism (SNP) of 117 selected dogs detected the SNP with the highest FST located in the intron of SOD1 adjacent to the c.118G>A mutation, supporting a selection signature on SOD1. Further genome-wide SNP analyses revealed no obvious changes in inbreeding levels and genetic diversity between the 2019 and 2022 populations. Our study highlights that genetic testing can help inform improved mating choices in breeding programs to reduce the frequency of risk variants and avoid inbreeding. This combined strategy could decrease the genetic risk of canine degenerative myelopathy, a fatal disease, within only a few years.

Demographics, clinical findings and diagnoses of cranial thoracic myelopathies (T1-T6 vertebrae) in cats.

OBJECTIVES: The aim of the study was to describe the patient demographics, clinicopathological features and presumptive or final diagnoses in cats with myelopathies between the T1 and T6 vertebrae. METHODS: This retrospective multicentre case study enrolled cases between 2015 and 2022 that were diagnosed with myelopathies between the T1 and T6 vertebrae as the primary cause for the presenting clinical signs. RESULTS: A total of 21 cases matched the inclusion criteria, 13 males (11 castrated and 2 entire) and 8 spayed females (median age 93 months; range 5-192). Most of the cases presented with a chronic and progressive history (76% and 86%, respectively), with a median duration of 29 days (range 1-2880). At the time of presentation, 90% of the cases were localised to the T3-L3 spinal cord segments based on neurological examination. The most common underlying pathology was neoplasia (42.9%), followed by inflammatory (24%), anomalous (19%), degenerative (9.5%) and vascular (4.8%) disorders. The most common location was T3-T4 (29%), followed by T2-T3 and T5-T6 (19% each). The cutaneous trunci reflex was normal in 86% of the cases and most of the cases (71%) did not show spinal discomfort upon admission. CONCLUSIONS AND RELEVANCE: Neoplasia was the most common cause of cranial thoracic myelopathy in this study. The lack of pathognomonic clinical signs for this specific region highlights the importance of assessing the entire thoracolumbar region up to and including at least the T1 vertebra when investigating cases with signs consistent with a T3-L3 myelopathy.

Diagnosis and management of dogs with degenerative myelopathy: A survey of neurologists and rehabilitation professionals.

BACKGROUND: Antemortem diagnosis of degenerative myelopathy (DM) in dogs is presumptive and there are no accepted guidelines for the management of this condition. HYPOTHESIS/OBJECTIVES: Describe current practices of neurology clinicians and physical rehabilitation professionals in the diagnosis and management of DM. ANIMALS: None. METHODS: Online surveys examining diagnosis and management of DM were constructed and distributed via neurology and rehabilitation listservs. RESULTS: One hundred ninety neurology and 79 rehabilitation professionals from 20 countries participated. Most neurology (142/189) and rehabilitation (23/39) respondents required genetic testing for the superoxide dismutase 1 (SOD1) mutation and 82/189 neurologists also required spinal magnetic resonance imaging (MRI) for presumptive DM diagnosis. Most neurology respondents recommended exercise (187/190) and physical rehabilitation (184/190). Over 50% (102/190) of neurology respondents perform rechecks on dogs diagnosed with DM. Rehabilitation respondents reported preservation or improvement of strength (78/79) and coordination (77/79) as therapeutic goals. At-home exercises (75/79), underwater treadmill (64/79), gait training (55/79), and strength building exercises (65/79) were used to maintain strength (58/79), coordination (56/79), muscle mass (56/79), and improve overall wellbeing (54/79). Neurology respondents reported that owners elect euthanasia when dogs become nonambulatory paraparetic whereas rehabilitation respondents report euthanasia when paraplegia and incontinence develop. CONCLUSION AND CLINICAL IMPORTANCE: The majority of dogs diagnosed with DM have not undergone advanced imaging, the combination of history, neurological findings, and genetic testing is heavily relied upon. Whereas the diagnosis of DM is frequently made by veterinary neurologists, continued care is often performed by rehabilitation professionals or primary veterinarians.

Lumbar vertebral canal stenosis due to marked bone overgrowth after routine hemilaminectomy in a dog.

BACKGROUND: Bone overgrowth after decompressive surgery for lumbar stenosis resulting in recurrence of neurological signs has not been reported in veterinary literature. However, there are few cases described in human medicine. CASE PRESENTATION: A 13-month-old entire female dog, a crossbreed between a Springer Spaniel and a Border Collie, weighing 24 kg, was referred with a 5-day history of progressive spastic paraplegia, indicative of a T3-L3 myelopathy. Magnetic resonance (MR) imaging revealed a right-sided L2-L3 compressive extradural lesion, compatible with epidural haemorrhage, which was confirmed by histopathology. The lesion was approached via right-sided L2-L3 hemilaminectomy and was successfully removed. One-year postoperatively the dog re-presented with pelvic limb ataxia. MR and computed tomography (CT) images demonstrated excessive vertebral bone formation affecting the right articular processes, ventral aspect of the spinous process of L2-L3, and contiguous vertebral laminae, causing spinal cord compression. Revision surgery was performed, and histopathology revealed normal or reactive osseous tissue with a possible chondroid metaplasia and endochondral ossification, failing to identify a definitive reason for the bone overgrowth. Nine-month postoperatively, imaging studies showed a similar vertebral overgrowth, resulting in minimal spinal cord compression. The patient remained stable with mild proprioceptive ataxia up until the last follow-up 18 months post-revision surgery. CONCLUSION: This is the first report in the veterinary literature of bone overgrowth after lumbar hemilaminectomy which resulted in neurological deficits and required a revision decompressive surgery.

Prevalence of SOD1 allele associated with degenerative myelopathy in canine population in Greece.

Canine degenerative myelopathy (CDM) is a late-onset fatal disorder associated with a point mutation of the superoxide dismutase 1 (SOD1) gene (c.118G > A). The purpose of this study was to determine the genotype and allele frequencies of this mutation in 108 dogs, mainly in Belgian Malinois and German Shepherd dogs with (CDM-affected group) and without CDM clinical symptoms (control group) in Greece. Genotyping of the c.118G > A mutation was possible by Sanger sequencing and PCR-RFLP. The observed genotype frequencies for the control group were 89.4% for the homozygous (G/G), 9.6% for the heterozygous (A/G), and 0.96% for the homozygous mutant (A/A) allele. The mutant allele was not common in the Belgian Malinois dogs (allele frequency = 0.029), but quite common in the German Shepherd dogs (allele frequency = 0.138). In the CDM affected group, all 4 dogs were homozygous for the mutant allele. These frequencies were close to those expected, indicating no significant departure from Hardy-Weinberg equilibrium. A strong but not statistically significant association between the mutant allele and CDM was observed. A previously identified deletion upstream of the mutation of interest was found at a high frequency (0.361) in the population.

A case of suspected canine multifocal cervical venous sinus thrombosis causing cervical myelopathy.

A 10-year-old spayed female standard poodle was admitted for marked cervical pain. Magnetic resonance imaging (MRI) suggested cervical venous sinus thrombi. An excellent clinical response to clopidogrel and warfarin combination was achieved. Repeat MRI showed partial resolution of the thrombosis. The etiology of the thrombosis is suspected to be due to the previous long-term, chronic use of corticosteroids. To the authors' knowledge, this is the first case report with follow-up imaging of canine venous sinus thrombosis. This clinical case report may help practitioners recognize this condition as a possible differential diagnosis for cervical pain, and it provides important guidelines in the prognosis. This case report highlights the use of anticoagulant therapy for 14 wk leading to complete resolution of clinical signs and to partial resolution of the thrombus 5 wk into the treatment, based on comparative MRI. Key clinical message: To the authors' knowledge, this is the first report of suspected multiple cervical venous sinus thrombi that includes comparative imaging into the course of therapy. The aim of this report is to provide additional information for future guidance on the duration of venous sinus thrombosis therapy.

Un cas de thrombose multifocale du sinus veineux cervical causant une myélopathie cervicale. Une femelle caniche standard stérilisée âgée de 10 ans a été présentée pour une douleur aigüe marquée au cou. L'imagerie par résonance magnétique (IRM) était évocatrice de thrombose du sinus veineux cervical. Une excellente réponse au traitement combinant Warfarine et Clopidogrel a été notée. L'étiologie suspectée d'être à l'origine de la thrombose est l'administration prolongée de corticostéroïdes. Jusqu'à maintenant, il s'agit du premier rapport de cas avec imagerie de suivi de thrombose du sinus veineux cervical. Il pourrait aider à reconnaître cette condition comme l'un des diagnostics différentiels lors de douleur cervicale et il fournit des indications importantes reliées au pronostic. Ce rapport met en évidence l'utilisation d'un anticoagulant pendant quatorze semaines conduisant à la disparition complète des signes cliniques reliés à la thrombose et à une résolution partielle de la thrombose notée sur l'IRM comparative 5 semaines suivant l'introduction du traitement.Message clinique clé :À la connaissance des auteurs, il s'agit du premier rapport de cas de multiples thromboses du sinus veineux cervical suspectées incluant une imagerie comparative au cours du traitement. L'objectif de ce rapport est de fournir de l'information supplémentaire à la formation de lignes directrices futures sur la durée de traitement de la thrombose veineuse cervicale.(Traduit par les auteurs).

Vertebral fixation does not affect recovery or recurrence of cervical intervertebral disc herniation in small dogs (< 15 kg).

OBJECTIVE: To compare the prognosis of small dogs with cervical intervertebral disc herniation (C-IVDH) when treated with ventral slot decompression (VSD) alone or with concomitant vertebral fixation (VF). ANIMALS: Small dogs (n = 303) weighing < 15 kg diagnosed with C-IVDH and treated with VSD. PROCEDURES: We recorded signalment, cervical myelopathy grade, surgical site, use of VF, degree of adjacent disc degeneration, recovery, recurrence, recurrence site, and postoperative course, including the time elapsed from recovery to recurrence. We examined factors associated with recovery and recurrence during the 30-month postoperative period using multivariate logistic regression analysis. RESULTS: VF did not affect recovery (P = .79). However, nonchondrodystrophic breeds had poorer recovery (OR, 5.89; P = .023) than chondrodystrophic breeds, and a higher preoperative cervical myelopathy grade (grade 3 or 4) was associated with poorer recovery (OR, 7.09 or 3.46, respectively; P = .019 or .042, respectively), compared with grade 1. VF did not affect recurrence (P = .79); however, increasing age was associated with recurrence (OR, 1.79; P = .001). CLINICAL RELEVANCE: In small dogs weighing < 15 kg, there was no difference in postoperative recovery and recurrence rates after VSD with or without concomitant VF. Therefore, in small dogs with C-IVDH, even if the slot volume is increased to remove sufficient disc material during VSD, a good prognosis can be achieved with or without VF.

Rehabilitation Therapy for the Degenerative Myelopathy Patient.

Degenerative myelopathy is an inherited, progressive, neurodegenerative disorder affecting the spinal cord of dogs. There is no treatment of the disease. Physical rehabilitation is the only intervention that slows progression and prolongs quality of life. Further studies are needed to develop advanced treatment options and to better characterize the use of complementary therapeutic modalities in palliative care for these patients.

A novel surgical technique for treatment of cervical vertebral stenotic myelopathy (wobbler syndrome) in a filly.

Cervical vertebral stenotic myelopathy (CVSM), also known as equine wobbler syndrome or cervical ataxia, is a devastating neurological syndrome resulting from compression of the spinal cord at the cervical region. This report describes a novel surgical technique for treatment of 16-month-old Arabian filly with CVSM. The filly showed grade 4 ataxia, hypermetria, weakness of the hind limbs, stumbling during walking, and abnormal gait. Case history, clinical signs and myelography revealed spinal cord compression between the C3 and C4 and C4-C5. The filly underwent a novel surgical interference for decompression and stabilization of the point of stenosis using specially designed titanium plate and intervertebral spacer. Evidence of arthrodesis with absence of complications was confirmed by periodic radiography over eight months of postoperative care. The new technique applied in this cervical surgery was efficient for the decompression and stabilization of the vertebrae, allowing arthrodesis development and remission of the clinical signs. The obtained results encourage further assessment of this novel procedure in horses clinically affected by CVSM.

Non-traumatic hemorrhagic myelopathy in dogs.

BACKGROUND: Non-traumatic spinal cord hemorrhage (NTSH) is an uncommon cause of myelopathy in dogs. OBJECTIVES: Describe the clinical characteristics, concurrent medical conditions and underlying causes, magnetic resonance imaging (MRI) findings and outcome in dogs with NTSH. ANIMALS: Dogs diagnosed with NTSH using gradient echo T2-weighted (GRE) sequences with or without histopathological confirmation of hemorrhage were included. Dogs with a traumatic cause were excluded, including those with compressive intervertebral disc extrusion. METHODS: Retrospective descriptive study; the databases of 2 referral hospitals were searched between 2013 and 2021. RESULTS: Twenty-three dogs met inclusion criteria. The onset of signs was acute and progressive in 70% of cases; spinal hyperesthesia was variable (48%). Hemorrhage was identified in the thoracolumbar spinal segments in 65% of dogs. An underlying cause was identified in 65% of cases. Angiostrongylus vasorum represented 18% of the total cohort, followed by steroid-responsive meningitis arteritis (SRMA; 13%). Overall, 64% of dogs had a good or excellent outcome, regardless of cause; which was increased to 100% for SRMA, 75% for A. vasorum and 75% for idiopathic NTSH. Outcome was not associated with neurological severity. Recovery rate was 67% and 50% for nociception-intact and nociception-negative dogs, respectively. CONCLUSIONS: Larger prospective studies would be required to define prognostic factors for dogs with NTSH, but outcome appeared to be most influenced by the underlying cause, as opposed to neurological severity at presentation.

Cerebrospinal fluid and serum proteomic profiles accurately distinguish neuroaxonal dystrophy from cervical vertebral compressive myelopathy in horses.

BACKGROUND: Cervical vertebral compressive myelopathy (CVCM) and equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) are leading causes of spinal ataxia in horses. The conditions can be difficult to differentiate, and there is currently no diagnostic modality that offers a definitive antemortem diagnosis. OBJECTIVE: Evaluate novel proteomic techniques and machine learning algorithms to predict biomarkers that can aid in the antemortem diagnosis of noninfectious spinal ataxia in horses. ANIMALS: Banked serum and cerebrospinal fluid (CSF) samples from necropsy-confirmed adult eNAD/EDM (n = 47) and CVCM (n = 25) horses and neurologically normal adult horses (n = 45). METHODS: . A subset of serum and CSF samples from eNAD/EDM (n = 5) and normal (n = 5) horses was used to evaluate the proximity extension assay (PEA). All samples were assayed by PEA for 368 neurologically relevant proteins. Data were analyzed using machine learning algorithms to define potential diagnostic biomarkers. RESULTS: Of the 368 proteins, 84 were detected in CSF and 146 in serum. Eighteen of 84 proteins in CSF and 30/146 in serum were differentially abundant among the 3 groups, after correction for multiple testing. Modeling indicated that a 2-protein test using CSF had the highest accuracy for discriminating among all 3 groups. Cerebrospinal fluid R-spondin 1 (RSPO1) and neurofilament-light (NEFL), in parallel, predicted normal horses with an accuracy of 87.18%, CVCM with 84.62%, and eNAD/EDM with 73.5%. MAIN LIMITATIONS: Cross-species platform. Uneven sample size. CONCLUSIONS AND CLINICAL IMPORTANCE: Proximity extension assay technology allows for rapid screening of equine biologic matrices for potential protein biomarkers. Machine learning analysis allows for unbiased selection of highly accurate biomarkers from high-dimensional data.

Thoracolumbar myelopathies in pug dogs.

BACKGROUND: Constrictive myelopathy (CM) involving a fibrous band around the spinal cord is a newly recognized disease in pug dogs. OBJECTIVES: To identify the frequency of CM based on diagnostic imaging supplemented with necropsy; to determine whether a relationship exists between the sites of CM and other described T3-L3 myelopathies; and to determine the frequency of caudal articular process dysplasia (CAPD). ANIMALS: Thirty-two client-owned pug dogs diagnosed with a chronic, progressive T3-L3 myelopathy based on neurological examination performed by a board-certified neurologist. METHODS: This is a prospective study. All dogs underwent computed tomography (CT) and magnetic resonance imaging (MRI) reviewed by a board-certified radiologist. Magnetic resonance imaging abnormalities were categorized into diseases; CM only, CM plus other non-CM condition(s), or non-CM condition. Sites of CAPD were reported on CT. Nineteen dogs underwent necropsy. RESULTS: Magnetic resonance imaging revealed 3 dogs with CM only, 17 with CM plus at least 1 other myelopathy, 11 dogs with non-CM myelopathies only, and 1 with no MRI abnormalities. Nineteen of 32 dogs had >1 myelopathy diagnosis on MRI whereas 15/32 had >1 site of spinal cord compression. All dogs had CAPD at >1 site in the T3-L3 vertebral column on CT. CONCLUSIONS AND CLINICAL IMPORTANCE: Constrictive myelopathy affected more than half of pug dogs presenting with chronic thoracolumbar myelopathies. Most had multilevel disease, concurrent myelopathies, or both. There was no apparent relationship between anatomic locations of CAPD and most severe myelopathy or myelopathy type.