Case report: Radiofrequency-induced thermal burn injury in a dog after magnetic resonance imaging.

A 10-year-old male Shar-Pei was referred for lethargy and proprioceptive deficits of the left thoracic limb. An magnetic resonance imaging (MRI) examination of the cervical spinal column and the brain was performed. The MRI examination of the brain was normal. A left-sided C3-C4 intervertebral disc extrusion with spinal cord compression was diagnosed. Medical treatment was elected. Within a week after the MRI examination, the dog presented with deep partial-thickness skin burn wounds in both axillae. Since the specific absorption rate had not exceeded the safety limits during any of the scans and no other procedures or circumstances were identified that could possibly have resulted in burn injuries, the thermal burn injuries were diagnosed as radiofrequency (RF) burns. The wounds healed by secondary intent over the next month. RF burns are the most reported complication in humans undergoing MRI but have not been reported in veterinary patients. Clinicians and technicians should consider the potential risk for RF burns in veterinary patients and take precautions regarding positioning of the patient and take notice of any signs of burn injury when performing follow-up examinations.

Vertebral Osteosarcoma in Two Cats-Diagnosis, Treatment, and Outcome.

In this case report, we describe the diagnosis, treatment, and outcome of two feline cases of vertebral osteosarcoma. Case 1: A 6-year-old female neutered domestic longhaired cat was presented with progressive paraparesis, ataxia, and spinal hyperesthesia. MRI of the thoracolumbar spinal cord and vertebral column revealed a strongly contrast-enhancing mass lesion originating from the dorsal lamina and spinous process of T13. The lesion caused extradural compression of the spinal cord. Surgical debulking was performed, and the histopathological evaluation of surgical biopsies was consistent with vertebral osteosarcoma. The cat was paraplegic with intact nociception post-surgery. Subsequently, the cat recovered ambulation while remaining mildly ataxic and paraparetic at long-term follow-up. Post-operative chemotherapy was started with doxorubicin. CT scans at 2, 4, 9, 13, and 20 months post-surgery showed no signs of local recurrence or metastasis. Case 2: A 15.5-year-old male neutered domestic shorthaired cat was presented with progressive paraparesis, tail paresis, and spinal hyperesthesia. Radiographs and CT scan of the lumbar vertebral column showed a large mass originating from the dorsal lamina and spinous process of L6, suggestive of neoplasia, with severe compression of the spinal cord. Surgical debulking was performed, and the histopathological evaluation was consistent with vertebral osteosarcoma. Post-operative chemotherapy was started with doxorubicin. Seven months post-surgery, the patient was neurologically normal with no signs of metastatic disease. This case report highlights the possibility of good outcomes after the surgical treatment of feline vertebral osteosarcoma supplemented with post-surgical chemotherapy.

Hemophilia A Resulting in Severe Hyperesthesia Due to Extraparenchymal Spinal Cord Hemorrhage in a Young Golden Retriever Puppy.

A ten-week-old male Golden retriever puppy was presented with severe hyperesthesia, mild neurological deficits and episcleral bleeding. Clotting times showed a normal prothrombin time (PT) and prolonged activated partial thromboplastin time (aPPT). Computed tomography (CT) of the vertebral column showed intradural, extraparenchymal hyperattenuating changes on precontrast CT images and epidural mass lesions, suggestive of hematorrhachis. Hemophilia A was confirmed by a low-factor VIII activity (FVIII:C). Although the dog improved clinically with intravenous analgesia and cage rest, it was euthanized by the owners' choice because of the risk of developing future episodes of spontaneous hemorrhage. In young male puppies with severe hyperesthesia and mild neurological deficits, hemophilia A should be considered as a possible differential diagnosis.

Fast three-dimensional contrast-enhanced magnetic resonance angiography of the canine lumbar spinal cord vascular supply: A feasibility study.

Magnetic resonance angiography (MRA) is the noninvasive spinal cord vascular imaging modality of choice in human medicine. The aim of this exploratory, prospective, descriptive study was to assess the feasibility of fast three-dimensional (3D) contrast-enhanced (CE) MRA for visualization of spinal vascular structures in the canine lumbar region. Fourteen canine patients weighing > 5 kg were included. The lumbar arteries were consistently visualized (14/14;100%). Spinal arteries, radicular branches, great radicular artery (of Adamkiewicz), ventral spinal artery, and dorsal spinal arteries were not visualized (0/14;0%). The internal vertebral venous plexus was visualized in 11 of 14 (79%) dogs. Overall, the results of this study show that fast 3D CE-MRA of the lumbar region in dogs is feasible. However, the smaller arteries responsible for the spinal cord vascular supply were not visualized in this study.

Vertebral vascular canal dysplasia in French and English Bulldogs: Clinical, CT, and MRI characteristics and prevalence.

The authors have observed a vertebral anomaly in French and English Bulldogs and termed this anomaly "vertebral vascular canal dysplasia (VVCD)." No previously published descriptions of this anomaly were found. The aims of this retrospective, multi-institutional, observational study were to (1) describe the clinical, CT, and MRI characteristics of VVCD, and (2) estimate the prevalence and describe the characteristics of VVCD in a group of French and English Bulldogs. For descriptions of the anomaly, medical records and imaging studies of nine clinical cases with VVCD from several countries were reviewed. For estimation of prevalence, imaging studies of French and English Bulldogs from the United Kingdom (UK) and Italy were reviewed. All clinical case dogs had ≥5 thoracic vertebrae with VVCD affecting >50% of vertebral body height (VBH). The prevalence of VVCD involving ≥1 thoracic vertebra in the UK population (CT identified) of English Bulldogs and French Bulldogs was, respectively, 83.3% (30/36) and 68.3% (28/41). English Bulldogs had significantly more thoracic vertebrae with VVCD than French Bulldogs (P = < 0.01). The prevalence of VVCD in ≥1 thoracic vertebra in the Italian population (MRI identified) of English Bulldogs and French Bulldogs was, respectively, 21.7% (5/23) and 6.6% (7/106). Vertebral vascular canal dysplasia was observed in normal as well as in malformed vertebrae (e.g., hemivertebrae). Findings from the current study introduced descriptions of VVCD that can be used as background for future studies.

Quality of life in dogs with idiopathic epilepsy and their owners with an emphasis on breed-A pilot study.

Epilepsy in dogs is a common chronic and serious disorder and may have an impact on the quality of life of the owners as well as the dogs themselves. The aim of this pilot study was to investigate the QoL score of dogs suffering from idiopathic epilepsy and their owners and if possible, investigate whether a breed specific difference exists. Owners, either Dutch or Belgium, were asked to participate in a web based SurveyMonkey questionnaire. A total of 402 questionnaires representing 402 dogs with epilepsy were suitable for further analysis. Of the 402 dogs, 253 were males and 149 were females. Ninety-nine different breeds were represented. Fourteen breeds (177 dogs in total) were used to calculate breed specific scores; Australian Shepherd (n = 8), Beagle (n = 7), Belgian Tervuren dog (n = 9), Belgian Groenendaeler dog (n = 8), Border Collie (n = 38), Chihuahua (n = 9), Dachshund (n = 13), Drentsche Patrijshond (a Dutch partridge dog) (n = 14), French Bulldog (n = 12), Golden Retriever (n = 17), Labrador Retriever (n = 18), and Rottweiler (n = 12). For the Border Collie, there was a statistically significant correlation between "epilepsy related death," the severity of the seizures (p < 0.001) and cluster seizures (p < 0.001). The quality of life of the Border Collie was scored lower compared to all other dogs (p = 0.02). There were three breeds that had a minimal decrease in the overall quality of life score compared to all other dogs: the Chihuahua (p = 0.03), Dachshund (p = 0.001), and Golden retriever (p = 0.01). The score for "caring for my epileptic dog decreases my own QoL" was high for the Border Collie, Boxer, French Bulldog, and Rottweiler, but was only found to be statistically significantly higher in the Border Collie (p = 0.01). Scores for the Golden Retriever (p = 0.04) and Labrador (p = 0.006) were lower. In conclusion, this study reports breed specific quality of life scores of dogs with epilepsy and their owners, and underlines that breed by itself, is also an important factor when managing epilepsy in dogs.

Suspected acquired narcolepsy in 8 dogs.

BACKGROUND: Acquired narcolepsy has rarely been reported in veterinary medicine. OBJECTIVE: To describe the presentation, clinicopathological features, diagnostic imaging findings, and management of dogs with suspected-acquired narcolepsy. ANIMALS: Eight dogs with clinical features consistent with acquired narcolepsy. METHODS: A call for suspected cases of acquired narcolepsy was made online, followed by a retrospective review of detailed medical records of potential cases. Dogs were included if episodes consistent with cataplexy were present during examination by a board-certified veterinary neurologist and diagnostic work-up included magnetic resonance imaging of the brain and analysis of cerebrospinal fluid. RESULTS: Seven French Bulldogs and 1 Chihuahua (age range, 9-66 months) were included. Meningoencephalitis of unknown origin was diagnosed in 2 dogs, extracranial foci of inflammation were identified in 2 dogs (aspiration pneumonia, esophagitis, otitis media), and no abnormalities were found on diagnostic investigations in 4 dogs. Prednisolone was used in the management of all dogs, 6 dogs received imipramine, and 2 received cytosine arabinoside. An initial remission of signs was observed in all dogs, but a subsequent relapse of clinical signs was recorded for 4 dogs, of which 3 responded to adjustment or resumption of treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: The presence of cataplexy episodes should prompt a thorough diagnostic work-up to exclude the presence of intracranial (and extracranial) pathology. The potential for both remission and relapse of signs in suspected acquired cases is important for clinicians and owners to be aware of.

Comparison of signalment and computed tomography findings in French Bulldogs, Pugs, and English Bulldogs with and without clinical signs associated with thoracic hemivertebra.

BACKGROUND: Although thoracic hemivertebra can cause neurological signs, they occur commonly in neurologically normal dogs. OBJECTIVES: To evaluate whether computed tomography (CT) findings and factors associated with signalment can be used to differentiate between dogs with and without neurological signs associated with hemivertebra. ANIMALS: One hundred sixty dogs with ≥1 hemivertebrae were retrospectively studied. This group consisted of 40 dogs with clinical signs caused by hemivertebra and 40 French Bulldogs, 40 Pugs, and 40 English Bulldogs that underwent CT for reasons unrelated to neurological disease. METHODS: All dogs underwent CT and affected dogs also underwent magnetic resonance imaging. All CT studies were randomly evaluated by an observer blinded to signalment and clinical status. The following variables were evaluated: presence, number, location, and subtype of hemivertebra; presence of vertebral subluxation; severity of vertebral canal stenosis; presence, location, and severity of kyphosis, and number of vertebrae involved in the kyphotic segment. Statistical modeling was performed to identify factors associated with clinical status. RESULTS: Pug breed (odds ration [OR], 10.8; P = .01), more severe kyphosis (OR, 1.1 per grade increase; P < .001), fewer instead of more observed hemivertebrae (OR, 0.8; P = 0.03), and ventrolateral hypoplasia hemivertebra subtype (OR, 4.0; P = .011) were associated with higher likelihood of neurological disease. A Cobb angle of 34.5 degrees corresponded with the highest combined sensitivity and specificity to differentiate between clinically affected and unaffected dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: The variables identified could aid in differentiating between clinically relevant and irrelevant hemivertebra in small breed brachycephalic dogs.

Caudal lumbar spinal cysts in two French Bulldogs.

BACKGROUND: Spinal cysts are rare findings in veterinary medicine, but they are increasingly recognized due to the availability of advanced imaging techniques. Extradural meningeal cysts in French Bulldogs have not been reported previously and arachnoid cysts (diverticula) have not been reported at the caudal lumbar (L6-L7) region in dogs. CASE PRESENTATION: Two French Bulldogs, aged 5 and 8 years, were referred for evaluation of lower back pain and bilateral hind limb neurological deficits. Neurologic examination revealed ataxia and postural deficits in both dogs. Magnetic resonance imaging (MRI) showed cauda equina compression due to a cyst-like lesion at the level of L6-L7 in both cases. The dogs underwent dorsal laminectomy and the meningeal cyst was completely removed in one dog and in the other dog the spinal arachnoid diverticula was marsupialized. In Case 1, histopathology of the cysts was performed and MRI was repeated. Both dogs were pain free during follow-up evaluations. CONCLUSIONS: Based on radiological, intra-operative and histopathological findings, the first case was diagnosed as a meningocele connected by a pedicle to the caudal tip of the dural sac forming a dural diverticulum categorized as an extradural spinal cyst type Ib, and Case 2 as a type III intradural arachnoid diverticula. It is concluded that spinal cysts should be included in the differential diagnosis of cauda equina syndrome and lower back pain in French Bulldogs. Results of these cases may be useful for diagnostic and treatment management.

Intervertebral Disc Degeneration in Warmblood Horses: Morphology, Grading, and Distribution of Lesions.

Equine intervertebral disc degeneration is thought to be rare and of limited clinical relevance, although research is lacking. To objectively assess pathological changes of the equine intervertebral disc and their clinical relevance, description of the normal morphology and a practical, biologically credible grading scheme are needed. The objectives of this study are to describe the gross and histological appearance of the equine intervertebral discs and to propose a grading scheme for macroscopic degeneration. Spinal units from 33 warmblood horses were grossly analyzed and scored. Of the 286 intervertebral discs analyzed, 107 (37%) were assigned grade 1 and grade 2 (considered normal) and were analyzed histologically. A nucleus pulposus and an annulus fibrosus could be identified macroscopically and histologically. Histologically, the nucleus pulposus was composed of a cartilaginous matrix and the annulus fibrosus of parallel collagenous bands. A transition zone was also histologically visible. Intra- and inter-observer reliability scores were high for all observers. Higher grades were associated with greater age. Gross changes associated with equine intervertebral disc degeneration (grades 3-5)-that is, yellow discoloration, cleft formation (tearing), and changes in consistency of the nucleus pulposus-were largely similar to those in humans and dogs and were most prevalent in the caudal cervical spine. Equine intervertebral disc degeneration was not associated with osteophyte formation. Changes of the vertebral bone were most common in the thoracolumbar spine but were not correlated with higher grades of intervertebral disc degeneration. Thus, changes of the vertebral bone should be excluded from grading for equine intervertebral disc degeneration.

The Myth of Fibroid Degeneration in the Canine Intervertebral Disc: A Histopathological Comparison of Intervertebral Disc Degeneration in Chondrodystrophic and Nonchondrodystrophic Dogs.

Since the seminal work by Hans-Jörgen Hansen in 1952, it has been assumed that intervertebral disc (IVD) degeneration in chondrodystrophic (CD) dogs involves chondroid metaplasia of the nucleus pulposus, whereas in nonchondrodystrophic (NCD) dogs, fibrous metaplasia occurs. However, more recent studies suggest that IVD degeneration in NCD and CD dogs is more similar than originally thought. Therefore, the aim of this study was to compare the histopathology of IVD degeneration in CD and NCD dogs. IVDs with various grades of degeneration (Thompson grade I-III, n = 7 per grade) from both CD and NCD dogs were used (14 CD and 18 NCD dogs, 42 IVDs in total). Sections were scored according to a histological scoring scheme for canine IVD degeneration, including evaluation of the presence of fibrocyte-like cells in the nucleus pulposus. In CD dogs, the macroscopically non-degenerated nucleus pulposus contained mainly chondrocyte-like cells, whereas the non-degenerated nucleus pulposus of NCD dogs mainly contained notochordal cells. The histopathological changes in degenerated discs were similar in CD and NCD dogs and resembled chondroid metaplasia. Fibrocytes were not seen in the nucleus pulposus, indicating that fibrous degeneration of the IVD was not present in any of the evaluated grades of degeneration. In conclusion, intervertebral disc degeneration was characterized by chondroid metaplasia of the nucleus pulposus in both NCD and CD dogs. These results revoke the generally accepted concept that NCD and CD dogs suffer from a different type of IVD degeneration, in veterinary literature often referred to as chondroid or fibroid degeneration, and we suggest that chondroid metaplasia should be used to describe the tissue changes in the IVD in both breed types.

Increased caveolin-1 in intervertebral disc degeneration facilitates repair.

BACKGROUND: Preceding intervertebral disc (IVD) degeneration, the cell phenotype in the nucleus pulposus (NP) shifts from notochordal cells (NCs) to chondrocyte-like cells (CLCs). Microarray analysis showed a correlation between caveolin-1 expression and the phenotypic transition of NCs to CLCs. With a clinical directive in mind, the aim of this study was to determine the role of caveolin-1 in IVD degeneration. As a scaffolding protein, caveolin-1 influences several signaling pathways, and transforming growth factor (TGF)-ß receptors have been demonstrated to colocalize with caveolin-1. Therefore, the hypothesis of this study was that caveolin-1 facilitates repair by enhancing TGF-ß signaling in the IVD. METHODS: Protein expression (caveolin-1, apoptosis, progenitor cell markers, extracellular matrix, and phosphorylated Smad2 [pSmad2]) was determined in IVDs of wild-type (WT) and caveolin-1-null mice and canine IVDs of different degeneration grades (immunofluorescence, immunohistochemistry, and TUNEL assay). Canine/human CLC microaggregates were treated with chondrogenic medium alone or in combination with caveolin-1 scaffolding domain (CSD) peptide and/or caveolin-1 silencing RNA. After 28 days, gene and protein expression profiles were determined. RESULTS: The NP of WT mice was rich in viable NCs, whereas the NP of caveolin-1-null mice contained more collagen-rich extracellular matrix and fewer cells, together with increased progenitor cell marker expression, pSmad2 TGF-ß signaling, and high apoptotic activity. During canine IVD degeneration, caveolin-1 expression and apoptotic activity increased. In vitro caveolin-1 silencing decreased the CLC microaggregate glycosaminoglycan (GAG) content, which could be rescued by CSD treatment. Furthermore, CSD increased TGF-ß/pSmad2 signaling at gene and protein expression levels and enhanced the anabolic effects of TGF-ß1, reflected in increased extracellular matrix deposition by the CLCs. CONCLUSIONS: Caveolin-1 plays a role in preservation of the NC phenotype. Additionally, it may be related to CLC apoptosis, given its increased expression in degenerated IVDs. Nevertheless, CSD enhanced CLC GAG deposition in vitro, and hence the increased caveolin-1 expression during IVD degeneration may also facilitate an ultimate attempt at repair. Further studies are needed to investigate how caveolin-1 modifies other signaling pathways and facilitates IVD repair.

Inflammatory profiles in canine intervertebral disc degeneration.

BACKGROUND: Intervertebral disc (IVD) disease is a common spinal disorder in dogs and degeneration and inflammation are significant components of the pathological cascade. Only limited studies have studied the cytokine and chemokine profiles in IVD degeneration in dogs, and mainly focused on gene expression. A better understanding is needed in order to develop biological therapies that address both pain and degeneration in IVD disease. Therefore, in this study, we determined the levels of prostaglandin E2 (PGE2), cytokines, chemokines, and matrix components in IVDs from chondrodystrophic (CD) and non-chondrodystrophic (NCD) dogs with and without clinical signs of IVD disease, and correlated these to degeneration grade (according to Pfirrmann), or herniation type (according to Hansen). In addition, we investigated cyclooxygenase 2 (COX-2) expression and signs of inflammation in histological IVD samples of CD and NCD dogs. RESULTS: PGE2 levels were significantly higher in the nucleus pulposus (NP) of degenerated IVDs compared with non-degenerated IVDs, and in herniated IVDs from NCD dogs compared with non-herniated IVDs of NCD dogs. COX-2 expression in the NP and annulus fibrosus (AF), and proliferation of fibroblasts and numbers of macrophages in the AF significantly increased with increased degeneration grade. GAG content did not significantly change with degeneration grade or herniation type. Cytokines interleukin (IL)-2, IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, immune protein (IP)-10, tumor necrosis factor (TNF)-α, and granulocyte macrophage colony-stimulating factor (GM-CSF) were not detectable in the samples. Chemokine (C-C) motif ligand (CCL)2 levels in the NP from extruded samples were significantly higher compared with the AF of these samples and the NP from protrusion samples. CONCLUSIONS: PGE2 levels and CCL2 levels in degenerated and herniated IVDs were significantly higher compared with non-degenerated and non-herniated IVDs. COX-2 expression in the NP and AF and reactive changes in the AF increased with advancing degeneration stages. Although macrophages invaded the AF as degeneration progressed, the production of inflammatory mediators seemed most pronounced in degenerated NP tissue. Future studies are needed to investigate if inhibition of PGE2 levels in degenerated IVDs provides effective analgesia and exerts a protective role in the process of IVD degeneration and the development of IVD disease.

Gene expression profiling of early intervertebral disc degeneration reveals a down-regulation of canonical Wnt signaling and caveolin-1 expression: implications for development of regenerative strategies.

INTRODUCTION: Early degeneration of the intervertebral disc (IVD) involves a change in cellular differentiation from notochordal cells (NCs) in the nucleus pulposus (NP) to chondrocyte-like cells (CLCs). The purpose of this study was to investigate the gene expression profiles involved in this process using NP tissue from non-chondrodystrophic and chondrodystrophic dogs, a species with naturally occurring IVD degeneration. METHODS: Dual channel DNA microarrays were used to compare 1) healthy NP tissue containing only NCs (NC-rich), 2) NP tissue with a mixed population of NCs and CLCs (Mixed), and 3) NP tissue containing solely CLCs (CLC-rich) in both non-chondrodystrophic and chondrodystrophic dogs. Based on previous reports and the findings of the microarray analyses, canonical Wnt signaling was further evaluated using qPCR of relevant Wnt target genes. We hypothesized that caveolin-1, a regulator of Wnt signaling that showed significant changes in gene expression in the microarray analyses, played a significant role in early IVD degeneration. Caveolin-1 expression was investigated in IVD tissue sections and in cultured NCs. To investigate the significance of Caveolin-1 in IVD health and degeneration, the NP of 3-month-old Caveolin-1 knock-out mice was histopathologically evaluated and compared with the NP of wild-type mice of the same age. RESULTS: Early IVD degeneration involved significant changes in numerous pathways, including Wnt/ß-catenin signaling. With regard to Wnt/ß-catenin signaling, axin2 gene expression was significantly higher in chondrodystrophic dogs compared with non-chondrodystrophic dogs. IVD degeneration involved significant down-regulation of axin2 gene expression. IVD degeneration involved significant down-regulation in Caveolin-1 gene and protein expression. NCs showed abundant caveolin-1 expression in vivo and in vitro, whereas CLCs did not. The NP of wild-type mice was rich in viable NCs, whereas the NP of Caveolin-1 knock-out mice contained chondroid-like matrix with mainly apoptotic, small, rounded cells. CONCLUSIONS: Early IVD degeneration involves down-regulation of canonical Wnt signaling and Caveolin-1 expression, which appears to be essential to the physiology and preservation of NCs. Therefore, Caveolin-1 may be regarded an exciting target for developing strategies for IVD regeneration.

Intervertebral disc disease in dogs - part 2: comparison of clinical, magnetic resonance imaging, and histological findings in 74 surgically treated dogs.

The relationship between intervertebral disc (IVD) disease and IVD degeneration remains unclear. The aim of the present study was to compare the clinical severity of IVD herniation (IVDH), determined with a neurological grading system, with findings of magnetic resonance imaging (MRI) and histology using grading systems for IVD degeneration in chondrodystrophic (CD; n=37) and non-chondrodystrophic (NCD; n=37) dogs. This study is the second part of a two-part investigation, where the first part involved the development and validation of a histological grading scheme for classification of canine IVD degeneration. IVD degeneration graded on MRI correlated significantly with IVD degeneration graded on histology, but not with pre-operative clinical signs. Hansen type 1 hernias were more common in the cervical and thoracolumbar segments and Hansen type 2 hernias were more common in the lumbosacral segment. Type 1 hernias occurred more often in CD dogs than in NCD dogs, and CD dogs were clinically more severely affected than NCD dogs. The grade of IVD degeneration on MRI was higher in CD dogs than in NCD dogs, but there was no difference between dogs with type 1 and type 2 hernias. No significant differences in histological grade were found between CD and NCD dogs or between type 1 and type 2 hernias. It was possible to conclude that IVD degeneration did not correlate with the neurological severity of IVDH. The extent of degeneration identified on MRI correlated with degeneration seen histologically. Although the MRI grading system reflected the severity of IVD degenerative changes as confirmed by histopathology, it appeared less useful in predicting the clinical implications.

Intervertebral disc degeneration in the dog. Part 2: chondrodystrophic and non-chondrodystrophic breeds.

Dogs can be grouped into two distinct types of breed based on the predisposition to chondrodystrophy, namely, non-chondrodystrophic (NCD) and chondrodystrophic (CD). In addition to a different process of endochondral ossification, NCD and CD breeds have different characteristics of intravertebral disc (IVD) degeneration and IVD degenerative diseases. The anatomy, physiology, histopathology, and biochemical and biomechanical characteristics of the healthy and degenerated IVD are discussed in the first part of this two-part review. This second part describes the similarities and differences in the histopathological and biochemical characteristics of IVD degeneration in CD and NCD canine breeds and discusses relevant aetiological factors of IVD degeneration.

Intervertebral disc degeneration in the dog. Part 1: Anatomy and physiology of the intervertebral disc and characteristics of intervertebral disc degeneration.

Intervertebral disc (IVD) degeneration is common in dogs and can give rise to a number of diseases, such as IVD herniation, cervical spondylomyelopathy, and degenerative lumbosacral stenosis. Although there have been many reports and reviews on the clinical aspects of canine IVD disease, few reports have discussed and reviewed the process of IVD degeneration. In this first part of a two-part review, the anatomy, physiology, histopathology, and biochemical and biomechanical characteristics of the healthy and degenerated IVD are described. In Part 2, the aspects of IVD degeneration in chondrodystrophic and non-chondrodystrophic dog breeds are discussed in depth.

Soft tissue artifact in canine kinematic gait analysis.

OBJECTIVE: To investigate, noninvasively, the soft tissue artifact (STA) in canine kinematic gait analysis. STUDY DESIGN: Experimental study. ANIMALS: Labrador retrievers (n = 4). METHODS: Kinematic study: Reflective markers were glued to the skin over bony landmarks, with the distance between 2 markers representing the length of the underlying scapula, humerus, ulna, femur, and crus. The distance between these markers (marker distance [MD]) was measured with infrared cameras while the dogs stood still or walked on a treadmill. Fluoroscopy study: Radiopaque markers were glued on the skin over the spinous process of the L6 vertebra and the stifle to allow fluoroscopic observation of the markers and underlying skeletal segments while the dogs walked on the treadmill. The position of the markers was compared with the position of the underlying skeletal segments during different phases of the step cycle. RESULTS: Kinematic study: Significant differences were found between MD during standing and walking for all bones investigated. Mean percentage differences in MD ranged from -18% to +6%. Fluoroscopy study: Significant displacements relative to the bony landmarks were found ranging from 0.4 to 1.2 cm. CONCLUSIONS: Analysis of the motion of skeletal structures with the use of markers attached to the skin showed that the skin moves relative to underlying skeletal structures. When working with a 3-D motion-capture system using skin markers, researchers should be aware that the STA could significantly influence their results.

Pedicle screw-rod fixation of the canine lumbosacral junction.

OBJECTIVE: To assess pedicle screw-rod fixation (PSRF) of the canine lumbosacral junction (LSJ) ex vivo and in vivo. STUDY DESIGN: Ex vivo cadaver study and in vivo pilot study. SAMPLE POPULATION: Six canine cadaveric lumbosacral spinal specimens and 3 Greyhound dogs diagnosed with degenerative lumbosacral stenosis (DLSS). METHODS: Ex vivo study: PSRF of the LSJ was performed in 6 spinal specimens using guidelines and was evaluated by radiography, computed tomography, and magnetic resonance imaging. In vivo study: 3 Greyhounds diagnosed with DLSS had dorsal laminectomy and partial discectomy combined with PSRF of the LSJ. Curettage of the endplates with insertion of an autologous cancellous bone graft was performed to promote spinal fusion. During 18-month follow-up, dogs were monitored by clinical evaluation, diagnostic imaging, and force plate analysis. Dogs were euthanatized for reasons unrelated to PSRF or their lumbosacral disease, and postmortem imaging and histopathologic investigations of the LSJ were performed. RESULTS: Ex vivo study: Sixteen of 24 inserted screws had an acceptable placement. In vivo study: Ten of 12 inserted screws had acceptable placement. Clinical signs of ``lower'' back pain resolved at 4 weeks after surgery. Diagnostic imaging and histopathology showed no bony spinal fusion of the LSJ. Force plate analysis revealed a trend toward improved pelvic limb function relative to preoperative function. CONCLUSIONS: PSRF of the LSJ of large breed dogs is technically possible. Improvements to the surgical technique to induce spinal fusion and assessment in a larger sample size are required before it can be recommended.

Incidence of intervertebral disk degeneration-related diseases and associated mortality rates in dogs.

OBJECTIVE: To determine the incidence and distribution of intervertebral disk (IVD) degeneration-related diseases in a large population of dogs of various breeds, ages, and sexes and to determine mortality rates among dogs with these diseases. DESIGN: Epidemiological study. SAMPLE: Insurance data for dogs with veterinary health-care and life insurance coverage (n = 665,249 and 552,120, respectively). PROCEDURES: Insurance claim records of 1 company in Sweden were searched to identify dogs with IVD degeneration-related diseases; incidence and mortality rates were determined for affected dogs < 12 years old and < 10 years old, respectively. Only the first paid IVD degeneration-related claim for a dog was included in incidence rate calculations. RESULTS: The incidence rate of IVD degeneration-related diseases was 27.8 (95% confidence interval [CI], 27.2 to 28.4) occurrences/10,000 dog-years at risk (DYAR), indicating that approximately 0.3% of dogs/y in this population were affected. Miniature Dachshund was the most highly represented breed, followed by Standard Dachshund and Doberman Pinscher (237.1 [95% CI, 212.9 to 261.4], 141.5 [95% CI, 135.5 to 147.4], and 88.6 [95% CI, 72.1 to 105.2] occurrences/10,000 DYAR, respectively). The incidence rate of IVD degeneration-related disease was greater in male than in female dogs and increased with age. Overall mortality rate attributed to IVD degeneration-related diseases was 9.4 (95% CI, 8.9 to 9.8) deaths/10,000 DYAR and was greater in males than in females. CONCLUSIONS AND CLINICAL RELEVANCE: Differences in incidence rates among various breeds suggested a genetic involvement. Knowledge of the distribution of IVD degeneration-related diseases among dogs of various breeds and ages may facilitate early diagnosis and preemptive treatments in patients at risk for developing these diseases.