Association of magnetic resonance assessed disc degeneration and late clinical recurrence in dogs treated surgically for thoracolumbar intervertebral disc extrusions.

BACKGROUND: Radiographic signs of intervertebral disc mineralization are thought to indicate sites of future recurrence of disc extrusion (Hansen type I) but the relationship between evidence of disc degeneration on magnetic resonance imaging (MRI) and future disc extrusion with recurrence of clinical signs has not been examined. OBJECTIVES: To examine the relationship between MRI-assessed degeneration of thoracolumbar intervertebral discs and late recurrence of clinical signs in dogs presented with acute thoracolumbar intervertebral disc extrusion and treated by hemilaminectomy alone. ANIMALS: Ninety-two client-owned dogs presented to 2 referral hospitals between 2009 and 2014. METHODS: Retrospective analysis of association between clinical signs consistent with recurrent thoracolumbar intervertebral disc extrusion and MRI evidence of disc degeneration in dogs undergoing hemilaminectomy for acute thoracolumbar intervertebral disc extrusion. Univariable and multivariable Cox regression analyses were used to explore associations between recurrence of clinical signs and several characteristics of T10-L3 discs at initial diagnosis. RESULTS: Ninety-two cases were included, of which 42 (46%) were Dachshunds and median age was 5.3 years. Clinical signs recurred in 33/92 (36%) dogs. Finding a completely degenerate disc in the T10 to L3 region (in addition to the operated site) at the time of surgery was associated with a hazard ratio of 2.92 (95% confidence interval: 1.37-6.20) for recurrence of clinical signs. CONCLUSIONS AND CLINICAL IMPORTANCE: Our results suggest that in cases of thoracolumbar intervertebral disc extrusion in dogs, recurrence of signs is likely if at least 1 completely degenerate disc in addition to the currently symptomatic disc is visible on MRI.

Extrusão de disco intervertebral caudal (coccígea) em um Basset Hound: primeiro relato de caso / First report of caudal intervertebral disk extrusion in a Basset Hound

Relata-se o primeiro caso no Brasil de doença do disco intervertebral (Hansen tipo I) entre as vértebras caudais (coccígeas) em uma cadela Basset Hound com seis anos de idade, castrada, pesando 16kg e com histórico de dor durante defecação e manipulação da região pélvica associada à inabilidade de mover, elevar ou abanar a cauda. Na radiografia simples, observou-se opacidade do forame intervertebral entre a quarta e a quinta vértebra caudal. O animal foi submetido à laminectomia dorsal modificada, seguida de fenestração do disco intervertebral afetado. Decorridos 15 dias da cirurgia, a paciente não demonstrava sinais de dor ao defecar e realizava movimentos de abano de cauda, mas ainda com desconforto na palpação e sem elevação da cauda acima da coluna vertebral, o que foi resolvido após 30 dias do procedimento cirúrgico. A relevância do caso está na inclusão, mesmo que rara, da doença do disco intervertebral caudal no diagnóstico diferencial em cães com dor durante a defecação e manipulação da cauda, sendo o exame radiográfico uma ferramenta auxiliar importante para o diagnóstico definitivo e o plano terapêutico.(AU)

We report here the first case in Brazil of an intervertebral disc disease (Hansen type I) between the caudal vertebrae (coccygeal) in a six-year-old Basset Hound dog, castrated, weighing 16 kg and history of pain during defecation and manipulation of the pelvic region, associated with the inability to move, raise and shake its tail. In the radiography survey, an opacity of the intervertebral foramen between the fourth and fifth caudal vertebra was observed. The animal underwent a modified dorsal laminectomy followed by fenestration of the affected intervertebral disc. After 15 days following surgery, the patient showed no signs of pain when defecating and was able to perform the tail wag movements, but with discomfort on palpation and could not rise the tail high up the spine, which was resolved after 30 days of surgery. The relevance of this report is the inclusion, even if rare, of the caudal intervertebral disc disease in the differential diagnosis in dogs with pain during defecation and handling of the tail, and the radiographic survey is an important auxiliary tool for definitive diagnosis and treatment plan for this disease.(AU)

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.

Spontaneous resorption of a herniated cervical disc in a dog detected by magnetic resonance imaging.

This report describes, for the first time in small animal literature, the spontaneous resorption of herniated Hansen type I intervertebral disc material in the cervical spine of a chondrodystrophic dog over a 4-month period, documented by magnetic resonance imaging. Clinical signs (cervical hyperpathia) responded to conservative treatment during the same period.

Résorption spontanée d'une hernie discale chez un chien détectée par imagerie par résonance magnétique. Cet article décrit, pour la première fois dans la littérature des petits animaux, la résorption spontanée d'une hernie Hansen de type I du matériel du disque intervertébral dans la colonne cervicale d'un chien chondrodystrophique pendant une période de 4 mois et documentée par imagerie par résonance magnétique (IRM). Les signes cliniques (hyperpathie cervicale) ont répondu à un traitement conservateur durant la même période.(Traduit par Isabelle Vallières).

Avaliação clínica de cães com doença do disco intervertebral (Hansen tipo I) submetidos à descompressão cirúrgica: 110 casos / Clinical evaluation of dogs with intervertebral disc disease (Hansen type I) submitted to surgical decompression: 110 cases

O objetivo deste estudo foi identificar cães com doença do disco intervertebral toracolombar (Hansen tipo I) submetidos ao tratamento cirúrgico em um serviço de rotina em neurologia de um hospital veterinário universitário no período de 2006 a 2014, e obter informações a respeito da idade, do sexo, da raça, local da extrusão, interpretação da mielografia, avaliação dos graus de disfunção neurológica, recuperação funcional desses cães e observar a ocorrência de recidiva dos sinais clínicos da doença. A raça mais frequente foi Dachshund (69%), seguida dos cães sem raça definida (14,5%). Os locais mais afetados foram entre T12-T13 (31,9%) e L1-L2 (19,1%). Dos 110 cães, 74 (67,3%) tiveram melhora dos sinais clínicos após o procedimento cirúrgico, sendo 54 (49,1%) considerados satisfatórios e 20 (18,2%), parcialmente satisfatórios. Destes cães, seis (8,1%) cães estavam em grau II, 19 (25,7%) em grau III, 35 (47,3%) em grau IV e 14 (18,9%) em grau V. Pode-se concluir que o tratamento cirúrgico promove recuperação funcional satisfatória na maioria dos cães com extrusão de disco toracolombar. O prognóstico para recuperação funcional após o tratamento cirúrgico é tanto melhor quanto menor for o grau de disfunção neurológica e o percentual de recidiva é baixo em animais submetidos a este tipo de terapia.(AU)

The aim of this study was to identify dogs with thoracolumbar intervertebral disc disease (Hansen type I) submitted for surgical treatment on a routine service in neurology in a university veterinary hospital in 2006-2014, and to get information about age, sex, breed, site of extrusion, interpretation of myelography, evaluation of the degree of neurological dysfunction, functional recovery of these dogs, and to verify the recurrence of clinical signs of disease. The most common breed was Dachshund (69%), followed by mixed breed (14.5%). The most affected sites were between T12-T13 (31.9%) and L1-L2 (19.1%). Of the 110 dogs, 74 (67.3%) improved clinical signs after surgery, 54 (49.1%) satisfactory and 20 (18.2%), in part satisfactory. From these dogs, six (8.1%) dogs were in grade II, 19 (25.7%) in grade III, 35 (47.3%) in grade IV, and 14 (18.9%) in grade V. It can be concluded that satisfactory surgical treatment promotes functional recovery in most dogs with thoracolumbar disk extrusion. The prognosis for functional recovery after surgical treatment is better the lower the degree of neurological dysfunction and the recurrence percentage is lower in dogs subjected to this type of therapy.(AU)

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.

Leprotic cervical spondylodiscitis.

Leprosy is a chronic infectious disease caused by the Mycobacterium leprae that leads to leprotic neuropathy involving the peripheral nerve and several characteristic skin lesions. Skeletal involvement can occur in peripheral joints, such as the wrist and the ankle. However, there is no report of an axial leprotic lesion involving the spine or paraspinal soft tissue. The authors report the first case of a leprotic cervical lesion involving the axial skeletal system. A 48-year-old male presented with neck pain and severe pain in the right suprascapular area and left arm. Preoperative MRI of the cervical spine revealed signal changes in the prevertebral soft tissue at the level of the C3, 4, 5 vertebral bodies. There were a lower signal intensity on T1-weighted image and high signal intensity on T2WI of the bone marrow at the level of the C5 and C6 vertebral bodies, and a C5/6 segmental ossification of the posterior longitudinal ligament. There were herniated cervical disc on the left C5/6 with C6 root and the right side of C6/7 with a C7 root compression. He was previously diagnosed with leprosy when he was 14 years old and received treatment intermittently over the course of 7 years. But patient did not disclose his past history. Surgical intervention was conducted using an anterior cervical approach. An incision was made in the anterior longitudinal ligament at C5/6, and a pinkish gray friable gelatinous material was observed on the C5/6 disc and on the anterior lower one-third surface of the C5 vertebral body. Specimens were obtained and subjected to pathological evaluation and microbiological culture. After C5/6 and C6/7 discectomies, nerve root decompression and autologous iliac bone grafting were performed at the C5/6 and C6/7 levels. The C5-6-7 vertebrae were fixed with an Atlantis cervical locking plate and a screw system. The pathological report indicated chronic inflammation with heavy plasma cell infiltration on the specimen. We sent the specimens to the Institute of Hansen's Disease, and polymerase chain reaction for leprosy tested positive. After surgery, his pain disappeared and he was given a prescription for antileprotic drugs. The authors describe the first case of leprotic cervical spondylodiscitis that was operatively treated in a 48-year-old patient with known leprosy history since his 14 years old.

Cytologic and histopathologic evaluation of extruded canine degenerate disks.

OBJECTIVE: To describe the cytologic and histopathologic appearance of degenerate disk material in dogs with Hansen type I intervertebral disk disease (IVDD). STUDY DESIGN: Case series. ANIMALS: Dogs (n=45) that had surgical intervention for Hansen type I IVDD (January-November 2007). METHODS: Impression smears and histopathologic sections were prepared from surgically removed degenerate disk material. All slides were evaluated for overall cellularity, quantity and attributes of extracellular matrix, types of cells present, and their cytomorphology. Histopathologic sections were also examined for presence of neovascularization and hemorrhage. RESULTS: Cytologically, 11 of 45 samples consisted of only extracellular matrix, 30 had evidence of inflammation, and 20 contained dysplastic spindloid cells. Histologically, hyaline cartilage predominated in 35 of 45 samples, fibrocartilage in 4, and spindloid cells in 6; 37 of 45 were inflamed, 37 were hemorrhagic, and 13 had neovascularization. CONCLUSIONS: The cytologic and histopathologic appearance of extruded degenerate disk material in dogs is variable and can include dysplastic spindloid cells. CLINICAL RELEVANCE: The variability in cytologic findings and frequent presence of dysplastic spindloid cells suggest that cytology alone may not be a reliable tool to differentiate degenerate canine disk material from a mesenchymal neoplasm.

Use of the ventrodorsal myelographic view to predict lateralization of extruded disk material in small-breed dogs with thoracolumbar intervertebral disk extrusion: 104 cases (2004-2005).

OBJECTIVE: To determine whether the ventrodorsal myelographic view can be used to accurately predict the circumferential location of extruded disk material in dogs with thoracolumbar intervertebral disk extrusion (IVDE) and to describe paradoxical contrast obstruction (PCO). DESIGN: Retrospective case series. ANIMALS: 104 dogs with Hansen type I IVDE. Procedures-Ventrodorsal myelographic views were reviewed, and contrast patterns were categorized according to 8 predetermined patterns. Agreement among observers was compared, and the predicted location of extruded disk material was compared with surgical findings. RESULTS: Agreement regarding myelographic pattern and location of extruded disk material was moderate (kappa = 0.74 and 0.80, respectively) among the 4 observers. Ninety-three (89%) dogs had myelographic evidence of lateralized extrusion, and in 83 of the 93 (89%), predicted location of extruded disk material matched the surgically confirmed location. In 33 of the 40 (83%) dogs with bilateral contrast column gaps of unequal length, disk material was found to be located on the side with the shorter, rather than the longer, contrast gap, a phenomenon described as PCO. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that the ventrodorsal myelographic view could be used to predict the circumferential location of extruded disk material in dogs with thoracolumbar IVDE more often than previously reported. The PCO phenomenon may be useful in determining the side of lateralization when contrast material does not outline the extruded disk material.

Aplastic articular facets in a dog with intervertebral disk rupture of the 12th to 13th thoracic vertebral space.

A 6-year-old, female spayed Pomeranian was presented with acute hind-limb paraplegia with the presence of deep pain perception and urinary incontinence. Myelography showed a Hansen type I herniation of the12th to 13th thoracic intervertebral space (T(12-13)). Articular facets of the T(12-13) and T(13) to first lumbar vertebra (L(1)) were absent. The spinal cord was decompressed using a bilateral T(12-13) modified lateral hemilaminectomy (pediculectomy). The aplastic sites were associated with minimal instability of the vertebral column, and stabilization of the vertebral column was not required. Familiarity with this condition is important, because articular facet aplasia may cause vertebral instability and may require an adjusted surgical approach or vertebral reduction and fusion following decompression.

A retrospective comparison of cervical intervertebral disk disease in nonchondrodystrophic large dogs versus small dogs.

Medical records of 144 small-breed dogs (< or =15 kg) and 46 medium- to large-breed dogs (>15 kg) with surgically confirmed, Hansen type I, cervical intervertebral disk extrusions were reviewed. The most common clinical presentation was cervical hyperesthesia. The most common sites affected were the second (C(2)) to third (C(3)) cervical intervertebral disk space in small-breed dogs and the sixth (C(6)) to seventh (C(7)) cervical intervertebral disk space in the larger dogs. Following surgery, 99% of the dogs had resolution of cervical hyperesthesia and were able to ambulate unassisted. Seven (4%) dogs required a second surgery; four of these were large-breed dogs.

Intervertebral disk disease in 10 cats.

The medical records of 10 cats diagnosed with intervertebral disk disease were reviewed. No apparent sex or breed predilection was found. The mean age of cats in the study was 9.8 years. Clinical signs included back pain, difficulty ambulating, and incontinence. Radiographs revealed narrowed disk spaces, mineralized intervertebral disks, and evidence of extradural compression on myelography or computed tomography. All intervertebral disk herniations occurred in the thoracolumbar spine, with a peak incidence at the fourth to fifth lumbar (L4-L5) intervertebral disk space. Eight cats had Hansen's type I intervertebral disk herniation. Surgery was performed in seven cats. All cats judged to have an excellent outcome had undergone surgical decompression.

Hansen type I disk disease at T1-2 in a dachshund.

A 7-year-old Dachshund was presented with chronic left thoracic limb lameness and acute neurological deficits to the hind limbs following trauma. A lesion was suspected between C7 and T2 on the basis of neurological examinations. Radiography and myelography identified a calcified intervertebral disk at C7-T1 and an extradural unilateral compressive lesion at T1-2. Computed tomography scans of the cranial thoracic spine revealed extrusion of disk material from the T1-2 intervertebral space resulting in marked spinal cord compression. Intervertebral disk disease is rarely reported at this location. The neurological condition deteriorated after a second myelogram, which was done to examine the thoracolumbar spine. A modified dorsal decompression of T1-2 was performed. The dog was euthanased due to further neurological deterioration 8 days after surgery.

Hemilaminectomy for the treatment of thoracolumbar disc disease in the dog: a follow-up study of 40 cases.

A study was made of dogs with Hansen type I thoracolumbar disc extrusions that had been treated by hemilaminectomy and fenestration of the affected disc. Follow-up information was available for 40 dogs undergoing treatment over a five-year period. The follow-up period ranged from 12 to 72 months (mean 34 months). The case details and the results of treatment of these 40 dogs are presented. All dogs were graded according to the degree of neurological dysfunction at the time of initial presentation and at the conclusion of the study period. Twenty-seven dogs (68 per cent) had no detectable signs of neurological dysfunction or thoracolumbar pain at the final assessment and a further eight dogs (20 per cent) had mild ambulatory paraparesis but were regarded by their owners as functional pets. Recurrence of neurological signs consistent with thoracolumbar disc disease was seen in five dogs (13 per cent) and was successfully resolved completely in one of three dogs that were treated.

Incidence of contralateral versus ipsilateral neurological signs associated with lateralised Hansen type I disc extrusion.

Asymmetrical neurological signs were noted in 50 dogs presenting with Hansen type I thoracolumbar disc extrusion. Thoracolumbar myelograms and surgical decompression were performed in all cases. Dogs were divided into two groups (acute and chronic) based on the duration of clinical signs prior to presentation to the University of Georgia. Lateralising extradural cord compressive lesions were noted on all myelograms. In the acute group, 35 per cent of the dogs had asymmetrical neurological signs contralateral to the myelographic and surgical lesion, while in the chronic group only 11 per cent had neurological signs contralateral to the lesion. There was found to be no significant difference in frequency of contralateral asymmetrical clinical signs between the two groups (Fischer's exact test; P = 0.095). The high frequency of contralateral signs documents the importance of thoracolumbar myelography for accurate localisation of the disc material before decompressive surgery.

Thoracolumbar intervertebral disk disease in large, nonchondrodystrophic dogs: a retrospective study.

Medical records of 62 large, nonchondrodystrophic dogs diagnosed with thoracolumbar intervertebral disk disease between March 1986 and February 1996 were reviewed. Fifty-seven (92%), primarily mixed-breed dogs (mean age, 6.6 years) had Hansen type I disease. Fifty-eight percent had acute onset. The interspace between the first (L1) and second (L2) lumbar vertebrae was affected most commonly. The outcomes of the 48 dogs available for follow-up after undergoing laminectomies were evaluated. Surgical success rate and mean time to walking for nonambulatory dogs with deep pain perception was 90% and seven weeks, respectively. Thirty-nine percent had residual deficits. Following surgery, 12% had recurrence of disk protrusion/extrusion at a different site.

Morphologic features of the cervical intervertebral disks and adjacent vertebral bodies of horses.

The intervertebral disks and adjacent vertebral bodies of the 2nd to 7th cervical vertebrae from 17 horses (3 months to 19 years of age) were examined grossly and by light microscopy. In each specimen, the disk tissue was fibrocartilagenous centrally and became more fibrous peripherally, but without a distinct demarcation between the nucleus pulposus and anulus fibrosus. Demarcation between the anulus fibrosus and the dorsal longitudinal ligament was not apparent. With increasing age of the horses, cellularity of the central fibrocartilagenous portion of the disk decreased. The caudal end plates of the vertebrae had an increase in width and bone density with increasing age. In specimens from horses of all ages, the cranial end plate of the vertebrae had only a thin rim of dense bone. The cranial physis of each vertebral body was closed at 3 years of age, whereas the caudal physis of vertebral bodies was discontinuous in 6- to 9-year-old horses and was completely absent in horses greater than or equal to 12 years. Disruption of fibers of the anulus fibrosus by small amounts of fibro-cartilage was observed in disks from 5 horses. This change was similar to a Hansen type II disk prolapse.