Partial surgical removal of an intramedullary epidermoid cyst from the spinal cord of a dog

An intramedullary space-occupying lesion in the form of an epidermoid cyst was diagnosed in a one-and-a-half-year-old flat-coated retriever. Dorsal laminectomy and durotomy were performed in order to establish the diagnosis followed by excision of one third of the cyst. The remaining cystic tissue that was intimately attached to the spinal cord parenchyma was left in place in order to avoid further damage to the nervous tissue. The dog's neurological status improved dramatically after the surgery, but deteriorated four months later due to recurrence of the cyst.

Laminectomy for 34 dogs with thoracolumbar intervertebral disc disease and loss of deep pain perception

The case details and the results of treatment of 34 dogs with thoracolumbar intervertebral disc disease, without deep pain perception, that had been treated by laminectomy and fenestration, are presented. The association of a number of potential prognostic factors with the neurological outcome is examined. Twenty-one dogs (62 per cent) recovered neurological function, seven (21 per cent) failed to recover neurological function and three (9 per cent) developed progressive myelomalacia postoperatively, while three dogs (9 per cent) were euthanized intraoperatively because of diffuse myelomalacia. Twenty of the dogs that recovered neurological function showed a return of deep pain perception within two weeks of decompressive surgery. Statistical analysis showed significant differences in the outcome between dogs that took less than one hour to lose the ability to ambulate and dogs with a longer duration of onset of inability to ambulate. The extent of spinal cord swelling determined by myelography was not found to be a useful prognostic indicator.

Intradural spinal arachnoid cyst in a dog

An 8-month-old, spayed female dog was presented with signs localizing a neurologic lesion between the 3rd thoracic and 3rd lumbar vertebrae. An arachnoid cyst was diagnosed by myelography, and a dorsal laminectomy with durotomy was performed. The dog continues to do well 1-1/2 year after surgery.

Cervical myelopathy associated with extradural synovial cysts in 4 dogs

Three Mastiffs and 1 Great Dane were presented to the University of Wisconsin Veterinary Medical Teaching Hospital for cervical myelopathy based on history and neurologic examination. All dogs were males and had progressive ataxia and tetraparesis. Degenerative arthritis of the articular facet joints was noted on survey spinal radiographs. Myelography disclosed lateral axial compression of the cervical spinal cord medial to the articular facets. Extradural compressive cystic structures adjacent to articular facets were identified on magnetic resonance imaging (1 dog). High protein concentration was the most important finding on cerebrospinal fluid analysis. Dorsal laminectomies were performed in all dogs for spinal cord decompression and cyst removal. Findings on cytologic examination of the cystic fluid were consistent with synovial fluid, and histopathologic results supported the diagnosis of synovial cysts. All dogs are ambulatory and 3 are asymptomatic after surgery with a follow-up time ranging from 1 to 8 months. This is the 1st report of extradural synovial cysts in dogs, and synovial cysts should be a differential diagnosis for young giant breed dogs with cervical myelopathy.

Surgical treatment of degenerative lumbosacral stenosis in dogs

OBJECTIVE

To study the epidemiology, clinical findings, and long-term outcome of surgical treatment of degenerative lumbosacral stenosis (DLSS) in dogs.

STUDY DESIGN

Retrospective study.

SAMPLE POPULATION

131 client-owned dogs with DLSS.

METHODS

The medical records of dogs with DLSS treated by dorsal laminectomy and dorsal fenestration were reviewed. The clinical diagnosis had been verified by diskography, epidurography or myelography, or a combination thereof.

RESULTS

The German shepherd breed was over-represented (56.5%), and males were more often affected than females (2:1). Historically, reluctance or pain when jumping, rising from a prone position, or climbing stairs (92.4%) and signs of pain or stiffness during extensive physical activity (85.5%) were the most frequent concerns. The most common physical and neurologic examination findings were pain in the lumbosacral area during hyperextension (97.7%) and on direct digital palpation (84.7%). A total of 93.2% of the dogs were improved clinically within the follow-up period (mean 26 +/- 17 months). Recurrence of clinical signs resembling DLSS was reported by the owner or diagnosed by clinical examination in 17.6% of the dogs with a mean onset of signs at 18 +/- 13 months postoperatively.

CONCLUSIONS

Surgical treatment of DLSS with dorsal laminectomy and fenestration generally resulted in good to excellent clinical outcome.

Correlation of clinical, radiographic, and surgical localization of intervertebral disc extrusion in small-breed dogs: a prospective study of 50 cases

OBJECTIVE

To compare prospectively clinical, radiographic, and surgical findings of intervertebral disc extrusion (IDE) localization in small-breed dogs and to determine the best means of lesion localization for the purpose of hemilaminectomy.

STUDY DESIGN

Clinical, radiographic, and surgical findings of small-breed dogs with thoracolumbar IDE were prospectively compared for agreement on lesion localization.

SAMPLE POPULATION

50 small-breed dogs with IDE treated at the three participating veterinary hospitals were included in the study if no other confounding diseases were identified and if the owner gave permission for diagnostic tests and surgery.

METHODS

Clinical and surgical findings were recorded by the surgeon assigned to the case. Radiographic studies were evaluated independently by two radiologists blinded as to the clinical and surgical findings. kappa values and 95% confidence intervals were calculated for agreement on lesion localization by clinical, radiographic, and surgical means and for agreement between radiologists.

RESULTS

kappa values for agreement of lesion localization were as follows: clinical versus surgical, 0.595; radiologist A versus radiologist B, 0.81; radiologist A versus surgical findings, 0.60; radiologist B versus surgical findings, 0.71. Both radiologists' interpretation of IDE localization agreed with surgical localization in 60% of cases.

CONCLUSIONS

Clinical lateralization of IDE was found to be the least reliable factor of those studied for determining on which side the hemilaminectomy should be performed. Results of this study differ from those of previous studies examining the reliability of myelography to localize the site of IDE accurately. The results of this study further suggest that surgery may not be an absolute standard for determination of the localization of IDE in small-breed dogs.

CLINICAL RELEVANCE

Intervertebral disc extrusion in small-breed dogs frequently results in bilateral distribution of extruded material. Computed tomography or magnetic resonance imaging may be necessary to delineate completely the distribution of extruded disc material in IDE.

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.

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.

Canine spinal nephroblastoma

An eight-month-old, female, mixed-breed dog was presented with bilateral hind-limb paralysis that reportedly developed over a two-to-three week period and was not associated with trauma. Plain radiographs of the spinal column were unremarkable, and a myelogram outlined an intramedullary mass of the spinal cord at the first lumbar (L1) vertebra. A hemilaminectomy was performed, and a mass that was identified histologically as nephroblastoma was excised from the spinal cord. Following surgery, the dog became fully ambulatory, and at 22 months postsurgery she remains clinically normal. The diagnosis, treatment, progression, histogenesis, and pathology of canine nephroblastoma are discussed.

Spinal tumors in 37 dogs: clinical outcome and long-term survival (1987-1994)

The current management of dogs with spinal canal neoplasia in a large veterinary institution was evaluated. Postoperative survival time and prognostic indicators for survival were examined. Spinal neoplasms in dogs and humans also were compared. Thirty-seven cases with histologically confirmed spinal tumors were included in the study. The cervical region was affected most commonly, and 23 (62%) of 37 cases had extradural tumors. A hemilaminectomy or a dorsal laminectomy was performed in each case; three cases received adjuvant treatment. Twelve (32%) cases were euthanized at the time of surgery, and two died immediately after surgery. One dog was euthanized 20 days after surgery because of persistent clinical signs. Twenty-two cases were followed postoperatively; nine different types of primary tumors were confirmed by histological examination of tissue specimens from these 22 cases, and three cases had metastatic lesions. The median survival time of these 22 cases was 240 days. Twelve (32%) of the 37 cases had nerve-sheath tumors; the median survival time for these 12 cases was 180 days. No prognostic indicators were identified. However, median survival times of cases with benign versus malignant tumor types were 1,410 days and 180 days, respectively (p of 0.07). Four cases each had a myxoma/myxosarcoma, a tumor previously unreported in the spinal canal in dogs.

Nonlymphoid vertebral canal tumors in cats: 11 cases (1987-1995)

OBJECTIVE

To determine outcome of cats with nonlymphoid tumors of the vertebral canal that undergo surgery.

DESIGN

Retrospective study.

ANIMALS

11 cats.

PROCEDURE

Information obtained from the medical records included signalment, tumor location, gross evaluation of completeness of surgical excision, histologic diagnosis, and survival time.

RESULTS

Median age of cats was 12 years: all cats had negative FeLV and feline immunodeficiency virus test results. All cats underwent a hemilaminectomy or dorsal laminectomy. The tumor was located in the thoracic portion of the vertebral column in 6 cats. Six cats had intradural-extramedullary tumors. Tumors included meningioma (n = 5), malignant nerve sheath tumors (2), and meningeal sarcoma, chondrosarcoma, lipoma, and osteosarcoma (1 each). One cat was lost to follow-up, 1 cat with meningioma was alive 1,400 days after surgery, and 1 cat with a nerve sheath tumor was alive 2,190 days after surgery. Median survival time for the other 4 cats with meningioma was 180 days (range, 30 to 600 days).

CLINICAL IMPLICATIONS

Cats with nonlymphoid vertebral canal tumors that undergo surgery may have a good prognosis.

Pathomechanism of pain-related behavior produced by allografts of intervertebral disc in the rat

STUDY DESIGN

This study was designed to evaluate whether allografts of intervertebral disc materials produce hyperalgesia in the rat and whether an immune response, pH, or chemicals correlate with the induced hyperalgesia.

OBJECTIVE

To elucidate the pathomechanisms of radicular pain secondary to lumbar disc herniation.

SUMMARY OF BACKGROUND DATA

It has been reported that a low pH, an autoimmune reaction, or chemical radiculitis is likely responsible for radicular pain associated with lumbar disc herniation. In animal studies, it has been shown that hyperalgesia (an increased sensitivity to painful stimuli) involves activation of phospholipase A2 and nitric oxide synthase.

METHODS

Fat, nucleus pulposus, and anulus fibrosus were allografted into the epidural space at L6 in the rat. Withdrawal response thresholds to mechanical stimuli and withdrawal response latencies to thermal stimuli on the tail and pH in the applied tissues were measured after surgery. Interleukin-1, phospholipase A2, and nitric oxide synthase were examined in the applied tissues using immunohistochemistry, nicotineamide adenine dinucleotide phosphate-diaphorase histochemistry, and in situ hybridization.

RESULTS

Allografted fat did not produce hyperalgesia. Allografts of nucleus pulposus and nucleus pulposus plus anulus fibrosis showed evidence of mechanical and thermal hyperalgesia, respectively. There were no observed changes in pH over time. Although interleukin-1 was demonstrated in all applied tissues, phospholipase A2 was only observed around the applied nucleus A2 was only observed around the applied nucleus pulposus and nucleus pulposus plus anulus fibrosus. Nitric oxide synthase was only markedly increased around the applied tissues.

CONCLUSION

The nucleus pulposus and anulus fibrosus produce different forms of hyperalgesia (mechanical vs. thermal) associated with different and distinct immunohistochemical changes. It is possible that radicular pain of a lumbar disc herniation results from chemicals, such as phospholipase A2 and nitric oxide.

The effects of internal fixation on calcium carbonate. Ceramic anterior spinal fusion in dogs

STUDY DESIGN

An anterior interbody fusion was performed in the canine thoracic spine. Either calcium carbonate or autologous iliac crest bone graft was used to fill a surgically created spinal defect between T7 and T8. Some of the spines were stabilized intraoperatively with anterior instrumentation. Four experimental arthrodesis groups were studied: iliac crest bone graft with or without instrumentation and ceramic with or without instrumentation.

OBJECTIVE

To evaluate the effects of internal fixation on an anterior interbody fusion using calcium carbonate ceramic, and to compare this with autologous iliac crest bone grafting.

SUMMARY OF BACKGROUND DATA

Bone grafting can be associated with significant morbidity, and an acceptable substitute material is sought. In vivo analysis of ceramic as a substitute has revealed fracture and failure of the implant. Creating a stable environment with internal fixation may improve the performance of ceramic as a bone graft substitute.

METHODS

Fusions were evaluated in 20 adult beagles 8 weeks after surgery. Structural properties of the fusion segment were evaluated with biomechanical testing. Histologic analysis was performed to determine junction healing, new bone formation, and revascularization.

RESULTS

Fusion segments with iliac crest bone graft and instrumentation were significantly stiffer than the other three groups in all tested modes of angular deformation. Greater junction healing was seen when instrumentation was used with iliac crest bone graft. Greater junction healing, new bone formation, and revascularization were observed when instrumentation was used with calcium carbonate ceramic. Most of the ceramic implants without fixation demonstrated near complete isolation with no revascularization.

CONCLUSIONS

Internal fixation resulted in histologically and biomechanically superior healing of autologous iliac crest bone graft in this canine model of anterior interbody fusion. Although fixation did not statistically improve the biomechanical properties of ceramic fusion segments, it had a profound effect on the ability of the ceramic to be revascularized and remodeled. Porous ceramic bone graft substitutes appear to depend on a stable environment for incorporation.

Dorsal laminectomy in the treatment of cervical intervertebral disk disease in small dogs: a retrospective study of 30 cases

Dorsal laminectomy was used to treat 30 dogs with cervical intervertebral disk disease. A variety of breeds were represented, and all animals weighted 15 kg or less. Myelography was utilized to locate each solitary disk herniation. All 30 cases progressed to complete recovery which indicates that dorsal laminectomy may be performed with success in small dogs with intervertebral disk disease.

Surgical treatment of intramedullary spinal cord neoplasia in two dogs

An area of intramedullary spinal cord enlargement at the thoracolumbar junction was identified by myelography in each of two dogs. Exploratory laminectomy followed by durotomy and myelotomy permitted removal of an intramedullary neoplasm in each dog. In one animal the tumour was diagnosed to be an ependymoma, in the other the tumour had the characteristics of a nephroblastoma. Following surgery each dog recovered quickly to pre-operative status or better. In one dog there was long term resolution of neurological deficits, while the other was euthanased because of persistent faecal incontinence.

Compression of spinal cord caused by spinal deformation in a cat

An 8-month-old cat with bilateral hindlimb paresis was admitted. Radiography revealed a curvature of the thoracic spine and a partial deformation of thoracolumbar vertebrae (dorsal extrusion of the cranial and caudal edges). Compression of the spinal cord (T9-L1 and L6-7) was found by myelography. Medicinal treatment did not yield the desired result. Hemilaminectomy and laminectomy were done to relieve pressure on the spinal cord leading to improved gait. It is, however, not clear whether this syndrome was primarily caused by metabolic or genetic factors.

Ultrasonography of the brain and vertebral canal in dogs and cats: 15 cases (1988-1993)

Medical records of 3 cats and 12 dogs with lesions of the brain (3 cats, 2 dogs) or vertebral canal (10 dogs) that underwent intraoperative ultrasonography were reviewed. Ultrasonography was performed after craniotomy, a ventral slot procedure, or laminectomy, using a real-time sector scanner with a 7.5- or 10-MHz transducer. In the 3 cats and 2 dogs with brain lesions, cerebral masses were hyperechoic, compared with normal brain, and were easily located. In the 2 dogs, ultrasonography was necessary to localize deep-seated cerebral lesions that could not be seen following craniotomy. In 7 dogs that underwent a ventral slot procedure because of prolapse of an intervertebral disk, ultrasonography was successfully used to assess completeness of disk removal. The remaining 3 dogs underwent dorsal laminectomy because intradural enlargement of the spinal cord (1 dog) or an intradural mass (2 dogs) could be seen myelographically. In the 2 dogs with intradural masses, intraoperative ultrasonography helped to delineate the extent of the tumor. In the third dog, spinal cord swelling was seen ultrasonographically; the histologic diagnosis was spinal cord edema.

[Neurosurgical therapy of intervertebral disk disease in dogs]

Intervertebral disc degeneration and protrusion or extrusion of disc material into the vertebral canal cause focal compressive myelopathy and radiculopathy, the most common neurological syndrome in dogs. Clinical findings are variable depending on duration and location of the lesion, volume of the mass and dynamic considerations (peracute massive extrusion, chronic partial extrusion, chronic progressive extrusion). Aim of this article is to provide compendium of at-the-present-time recommended methods of surgical treatment of intervertebral disc disease in the dog. In the case of compression of spinal cord is performed decompressive surgery (ventral cervical decompression, hemilaminectomy, minihemilaminectomy, dorsal laminectomy and foramenotomy). Fenestration is the only method of prophylaxis.

Comparison of hemilaminectomy and dorsal laminectomy for thoracolumbar intervertebral disc extrusion in dachshunds

Neurological improvement after decompressive surgery, without routine therapeutic or prophylactic disc fenestration, was evaluated retrospectively in a consecutive series of 93 dachshunds with thoracolumbar disc extrusion. In 24 per cent of procedures, deep pain sensation was not elicited in at least one hind paw before surgery. Median neurological status one to seven days after surgery, at the time of discharge, was significantly improved after hemilaminectomy compared with dorsal laminectomy (P < 0.05). After hemilaminectomy, deep pain sensation was not elicited in one or both hind paws of 8 per cent of dogs in which pain sensation was elicited before surgery, compared with 21 per cent after dorsal laminectomy (P > 0.05). Improvement in neurological grade at follow-up examination two to 12 weeks after hemilaminectomy was not significantly different compared with dorsal laminectomy (P > 0.05). Of dogs which were unable to walk before surgery, 83 per cent regained the ability to walk after hemilaminectomy, compared with 74 per cent after dorsal laminectomy (P > 0.05). In both groups, 50 per cent of dogs in which deep pain sensation was abnormal before surgery eventually regained the ability to walk after surgery (P = 1). One to two years after the first operation, a second laminectomy was performed in only 5 per cent of dogs because of extrusion of a different intervertebral disc which had not been fenestrated.

Spinal ganglioneuroma in a dog

A 10-year-old mixed-breed dog was examined because of lameness and mutilation of the left hind limb. Neurologic examination revealed ataxia, conscious proprioceptive deficit, muscle atrophy, lack of withdrawal reflex, and hyperreflexia of the patella of the left hind limb. Epidurography revealed right-sided deviation of the dye column at the sixth to seventh lumbar vertebrae. Laminectomy with cytoreduction was performed, and histologic examination revealed ganglioneuroma. Twelve months after surgery, clinical signs recurred and surgery was repeated. The dog's clinical signs were again palliated. The specific type of ganglioneuroma identified in this dog is amenable to surgical resection, unlike many types of spinal cord neoplasia.

Surgical treatment of cervical stenotic myelopathy in horses: 73 cases (1983-1992)

Seventy-three horses with cervical stenotic myelopathy underwent cervical vertebral interbody fusion (n = 63) or dorsal laminectomy (n = 10). Neurologic function improved in 77% of horses, and 46% of horses achieved athletic function (racing, race training, or pleasure riding) after cervical vertebral interbody fusion for static and dynamic spinal cord compressive lesions. Neurologic status improved in 4 of 10 horses after dorsal decompression for static compressive spinal cord lesions. The duration of clinical signs prior to surgical intervention was shorter for horses that achieved athletic function or improved by at least 2 neurologic grades than for horses that did not improve in neurologic status or improved 1 neurologic grade after cervical vertebral interbody fusion. The number of cervical spinal cord compressive lesions and age of horses did not affect the long-term surgical outcome of cervical vertebral interbody fusion. Seroma formation, implant failure, right laryngeal hemiplegia, and colitis were nonfatal complications associated with cervical vertebral interbody fusion. Dorsal laminectomy and cervical vertebral interbody fusion of static compressive lesions of the caudal cervical vertebral column were associated with fatal postoperative complications, including vertebral body fracture, spinal cord edema, and implant failure.

Decompressive procedures. Indications and techniques

Hemilaminectomy and dorsal laminectomy are the surgical techniques most suited for decompression of the thoracic, thoracolumbar, lumbar, and lumbosacral spine. Hemilaminectomy is preferred for decompressing the spinal cord before applying fixation devices for fractures/luxations. Dorsal laminectomy is the method of choice for exploration of the spinal canal and for decompression of the lumbosacral region. Either method is applicable to removal of herniated intervertebral disc material and fenestration of other disc spaces.

Thoracic spinal calcinosis circumscripta causing cord compression in two German shepherd dog littermates

Two young German shepherd dog littermates had progressive, painless, hindlimb ataxia. In both dogs plain radiography of the vertebral column revealed a solitary mineralised lesion on the dorsal laminae between the dorsal spines of the second and third thoracic vertebrae, and myelography with iopamidol demonstrated cord compression at the level of the lesions. The first dog died 18 hours after the myelography. A dorsal laminectomy performed in the second dog resulted in neurological improvement. A histopathological examination confirmed that both lesions were calcinosis circumscripta. The cause of the death of the first dog was meningitis.

A comparison of hemilaminectomy (with concomitant disc fenestration) and dorsal laminectomy for the treatment of thoracolumbar disc protrusion in dogs

The techniques of hemilaminectomy (with concomitant disc fenestration) and dorsal laminectomy were compared statistically in two groups of 30 dogs with thoracolumbar disc disease. On presentation all the dogs were unable to walk and were graded 1 to 3 according to their degree of neurological dysfunction. Nineteen had a previous history of thoracolumbar pain or hindlimb paresis. Radiography showed a narrowed disc space or extruded calcified disc material in 52 of the dogs and lumbar myelography revealed an extradural mass in 57; 24 of the dogs had clinical or myelographic lateralisation of signs. Hemilaminectomy significantly improved the ability to retrieve protruded disc material compared with dorsal laminectomy, and the removal of protruded disc material significantly improved the degree of recovery. Fenestration significantly reduced the recurrence of thoracolumbar disc disease.

Spinal lymphoma in cats: 21 cases (1976-1989)

Medical records of 21 cats with spinal lymphoma were reviewed. All cats were evaluated for neurologic deficits, although 85% of cats necropsied had multicentric disease. Eighty-one percent of cats had hind limb paresis. Results of FeLV tests were positive in 84.2% (16/19) of the cats, and 68.7% (11/16) of the cats had leukemic bone marrow. Spinal lymphoma was confirmed by necropsy in 13 cats, by examination of a biopsy specimen in 1 cat, and by examination of cells aspirated from an epidural lesion in 2 cats. In the remaining 5 cats, a presumptive diagnosis was made on the basis of neurologic examination findings, positive FeLV test results, and leukemic bone marrow. Nine cats were treated with chemotherapy alone. The complete remission rate was 50% in 6 cats given cyclophosphamide, vincristine, and prednisone. The median duration of complete remission was 14 weeks. Complete remissions were not observed in 3 cats given only corticosteroids. A single cat treated by laminectomy and postoperative chemotherapy had a prolonged remission (62 weeks). At necropsy, lymphoma of the CNS was limited to the vertebral canal in 10 of 13 cats; 2 cats had malignant tissue in the brain and vertebral canal, and in the remaining cat, the tumor extended into the brachial plexus. Most tumors extended over multiple vertebral bodies, and 4 cats had more than 1 level of spinal cord involvement. The lymphoma was high-grade lymphoblastic or immunoblastic type in all cats.

Healing characteristics of free and pedicle fat grafts after dorsal laminectomy and durotomy in dogs

Dorsal laminectomy and durotomy were performed at thoracic vertebrae 12 and 13 (T12-T13) and lumbar vertebrae 1 and 2 (L1-L2) in 12 normal dogs. A free fat graft harvested from subcutaneous tissue adjacent to the incision was placed over the T12-T13 laminectomy site. A 75 X 25 X 5 mm pedicle fat graft harvested from a similar location was placed over the L1-L2 laminectomy site. Three dogs each were euthanatized at weeks 2, 4, 8, and 16. With both types of fat grafts, an initial inflammatory stage reduced the size of the graft approximately 50%. Axonal degeneration and demyelination of the spinal cord resolved by week 16. At week 16, the durotomy sites had healed, but the dura mater was adhered to the spinal cord. No difference between the grafts could be demonstrated by antemortem myelography and cerebrospinal fluid analysis. There was no demonstrable advantage to the use of pedicle fat grafts.

Surgical treatment of sacral fracture in a horse

An 8-year-old Arabian stallion had signs of severe tailhead pruritus and slowly progressive loss of tail tone for 3 months. Palpation per rectum and radiography of the sacrocaudal region revealed a transverse, ventrally displaced fracture of the caudal portion of the sacrum. Surgical decompression and tail amputation resulted in complete recovery of athletic and reproductive function. Evidence of cauda equina neuritis was not seen on histologic examination of nerve roots obtained at surgery.

Metastatic thyroid solid-follicular carcinoma in the cervical portion of the spine of a dog

A metastatic thyroid solid-follicular carcinoma in the cervical portion of the spine was responsible for severe tetraparesis in a dog. Myelography revealed an extradural compressive lesion dorsal and to the right of the midline of C3. Histologic examination was used to diagnose the mass as a solid-follicular thyroid carcinoma. The primary tumor was not evident on cervical palpation or radiography. A dorsal laminectomy centered over C3 was performed, and all visible tumor was removed from the spine. The owner declined any further treatment for the dog.

Spinal trauma in dogs and cats: a review of 51 cases

The clinical and radiographical features, and the results of treatment of 41 dogs and 10 cats with traumatic injuries of the spine are reviewed. There was a poor correlation between the degree of vertebral displacement and the neurological condition of the animals. Eighteen cases were treated conservatively, 16 were treated surgically and 17 were destroyed. Surgery was reserved for animals with either severe or progressive neurological dysfunction, and vertebral body plating and hemilaminectomy were the commonest procedures. Of the cases treated conservatively 94.4 per cent showed significant neurological improvement compared with 87.5 per cent of those treated surgically.

Paraparesis caused by epidural granuloma in a cat

Caudal paraparesis in a cat was determined to be caused by an epidural mass. Surgical decompression was performed, and the mass was determined to be a granuloma. Fusobacterium and Bacteroides spp were isolated from the granuloma. Epidural granulomas are seldom reported in dogs and cats. Decompression and administration of antibiotics led to recovery of this cat even though in human beings an unfavorable prognosis is given if neurologic deficits have developed.

Laminectomy for relief of atlantoaxial subluxation in four horses

Malalignment of the atlas and axis was seen in 4 horses with an idiopathic form of atlantoaxial subluxation characterized by spinal cord compression on extension. The bone structure and density of the atlas and axis were radiographically normal in 3 of the 4 horses. Clinical signs appeared when the horses were 6 to 30 months old, and 3 of the 4 horses had a history of trauma. Although a congenital anomaly could not be ruled out, the cause was thought to be trauma. The horses were moderately to severely ataxic at the time of examination. Myelography revealed compression of the spinal cord at the atlantoaxial junction on extension. Flexion completely relieved the compression. In each horse, subtotal laminectomy of the caudal two thirds of the dorsal arch of the atlas was used to relieve the spinal cord compression. Two horses recovered fully, one had residual grade-1 neurologic deficits, and a fourth was euthanatized after it fractured a limb 6 weeks after surgery.

Influence of nonbiologic implants on laminectomy membrane formation in dogs

The effects of various surgical implants, spinal cord hypothermia, and glucocorticoid administration on formation of the laminectomy membrane were evaluated in 32 preconditioned chondrodystrophoid dogs. Modified dorsal laminectomies and full-length durotomies, from T12 to L1, were performed on all dogs. Dogs were allotted to 2 groups. Group-1 dogs (n = 20) were further allocated to 4 subgroups (a, b, c, and d) consisting of 5 dogs each. Group-1a dogs received no implant, group-1b dogs had absorbable gelatin sponges implanted, group-1c dogs had absorbable gelatin films implanted, and group-1d dogs had absorbable gelatin sponges and absorbable gelatin films implanted. Daily neurologic examinations permitted correlation of neurologic dysfunction with secondary spinal cord compression in those dogs in which it developed. The influence of these implants on laminectomy membrane formation and dural healing was assessed by gross and microscopic evaluation of transverse sections of the vertebrae and spinal cord after euthanasia of one member of each subgroup at 1, 2, 4, 8, and 16 weeks after surgery. Group-2 dogs (n = 12) were further allotted to 3 subgroups (a, b, and c) consisting of 4 dogs each. One dog in each group-2 subgroup underwent the same surgical procedures described for the group-1 subgroups (ie, 4 procedures/group-2 subgroup). The additional effects of 3 conventional supportive techniques (selective regional spinal cord hypothermia, glucocorticoid administration, or spinal cord hypothermia and glucocorticoid administration) on laminectomy membrane formation and on immediate postoperative recovery were examined in groups 2a, 2b, and 2c, respectively. Neurologic examinations were performed daily until this time. All dogs in group 2 were euthanatized 1 week after surgery for gross and microscopic examination of transverse sections of the vertebrae and spinal cord. Qualitative histopathologic effects of the different implants and supportive techniques on formation of the laminectomy membrane were determined. Statistical analysis of the degrees of secondary spinal cord compression was performed in group-1 dogs by measuring and comparing ratios of the vertical to the horizontal diameters of the transverse spinal cord sections from locations within (T12 to L1) and out of (T11, T11-12, L1-2, and L2) the region of surgical intervention. The vertical/horizontal diameter ratios measured from transverse sections from T11 to L2 in size-matched, untreated control dogs formed the standards for a mean roundness index of the spinal cord in the various anatomic locations of the vertebral column.(ABSTRACT TRUNCATED AT 400 WORDS)

Thoracic vertebral osteochondroma in a cat

A thoracic vertebral (T5) osteochondroma was discovered in a 1 1/2-year-old male blue Persian cat with a history of acute hind limb paresis. Myelography revealed a mass on the dorsal surface of the vertebral body, which resulted in dorsal compression of the spinal cord. A dorsal laminectomy was performed, and the mass was rongeured entirely from the vertebral body. Although the cat's progress was initially slow after surgery, its neurologic status was assessed to be near normal, 15 months later.

Spinal decompressive procedures and dorsal compartment injuries: comparative biomechanical study in canine cadavers

Effects of decompressive procedures or dorsal injuries on flexion-extension, 4-point bending properties of the L-3 and L-4 motion segment in dogs were quantitated and compared. Hemilaminectomy did not significantly (P less than 0.05) affect mechanical properties of the spine. Bilateral facetectomy caused a small increase in the range of motion and a 56% decrease in ultimate bending strength. Excision of the supraspinous and interspinous ligaments decreased the flexural stiffness of the spine, increased the range of motion of the interspace, and decreased ultimate flexion bending strength 62%. Dorsal laminectomy caused a marked decrease in spine stiffness in all phases of flexion and extension, increased the range of motion, and decreased ultimate flexion bending strength 75%. Seemingly, a hemilaminectomy was preferable to the dorsal laminectomy if adequate decompression and exploration were achieved with the hemilaminectomy.

Pathology of the vertebral column of horses with cervical static stenosis

Specimens of ligamentum flavum, joint capsule, and dorsal lamina were collected at surgery or necropsy from 25 horses with cervical static stenosis. All horses had myelographic evidence of dorsal compression of the spinal cord caused by soft tissue and/or bone in the caudal cervical area, primarily at C6-7. Most horses also had radiographic evidence of degenerative joint disease of articular facets. Histologically 19 horses had osteosclerosis and cartilage retention in the dorsal lamina, and 24 horses had increased fibrocartilage at the ligamentum flavum attachment to dorsal lamina. The ligamentum flavum and joint capsule had fibrovascular tissue in 20 horses. Fibrocartilaginous tissue, old hemorrhage, and fat necrosis were not unusual. One horse each had a synovial cyst, eosinophilic granulomas in the joint capsule, and osteochondrosis of articular facets. These findings indicate that abnormal biomechanical forces or instability of articulations result in stretching and tearing of the ligamentum flavum and joint capsule with subsequent fibrovascular and fibrocartilaginous proliferation, osteosclerosis of the dorsal lamina, and osteophyte formation on the articular facets.

Laminectomy for treatment of cauda equina syndrome in a cat

A 16-year-old spayed female Siamese cat was presented with a history of paraparesis and obstipation. The cat's impaired function was attributed to malalignment of the L7-S1 spine (cauda equina syndrome) and to traumatic fracture of the left femoral neck, with severe degenerative arthritis. Laminectomy resolved the cauda equina problem, and the hip joint was not treated.

Effects of dexamethasone and surgical hypotension on hepatic morphologic features and enzymes of dogs

Effects of corticosteroids and surgical stress on hepatic morphologic features and enzymes were studied in 18 mature dogs of mixed breeding: group 1, control (n = 3); group 2, dexamethasone (n = 5); group 3, dexamethasone and surgery (n = 5); and group 4, surgery (n = 5). Dexamethasone (2.2 mg/kg of body weight twice a day subcutaneously) was administered for 8 days in groups 2 and 3 dogs. All dogs were anesthetized with thiopental for 10 minutes on days 0, 2, and 4. On day 2, dogs in groups 3 and 4 were intubated and maintained on methoxyflurane and oxygen, and a liver biopsy, hemilaminectomy (T13-L1), and 15 minutes of hypotension (75/45 mm of Hg) induced by methoxyflurane were done. Serum alkaline phosphatase (ALP) activity, ALP isoenzymes, and alanine aminotransferase (ALT) activity were determined on days 0, 2, 3, 5, and 8. All dogs were euthanatized and necropsied on day 8. Serum hepatic enzyme activity and hepatic morphologic characteristics were normal for group 1 control dogs. The mean ALP and ALT were significantly (P less than 0.05) increased in dogs in groups 2, 3, and 4. In group 2, the mean ALP (days 5 to 8) and ALT (day 8) were significantly (P less than 0.05) increased. In group 3, the mean ALP and ALT activities were significantly increased on days 2 to 8. In group 4, the mean ALP was significantly increased on days 2 to 8 and the mean ALT was significantly increased on days 3 and 5. All other values were normal. A single isoenzyme band (Rf = 0.399 +/- 0.023, mean +/- SD) was identified in all dogs. Hepatic morphologic changes attributed to dexamethasone were mild-to-moderate vacuolation in a diffuse distribution on day 2 (group 3) and aggregates of moderate-to-severe vacuolation in mainly a periportal distribution on day 8 (groups 2 and 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of dexamethasone and surgical hypotension on the stomach of dogs: clinical, endoscopic, and pathologic evaluations

Effects of dexamethasone and surgical hypotension on the gastric mucosa of 15 dogs was evaluated by clinical, endoscopic, and pathologic studies. Dexamethasone produced acute reddening of the gastric mucosa with frank hemorrhage, digested blood, and possible gastric erosions, whereas dogs treated by surgical hypotension did not have marked changes in the gastric mucosa. Gastrointestinal disease observed in dogs with spontaneous spinal cord injury that were given dexamethasone and decompressive spinal surgery was not produced. The role of corticosteroids and surgical hypotension in the pathogenesis of gastric lesions and the potential for spinal cord injury to produce gastrointestinal disease is discussed.

Spinal decompression in a black bear

A 17-year-old black bear was examined because of posterior paralysis. Radiography revealed a narrowed disk space at T10-11, indicating a ruptured intervertebral disk. Subsequently, a dorsolateral hemilaminectomy was performed. Recovery from paralysis was slow because of the size of the animal (127 kg) and lack of appropriate physical therapy. When evaluated more than 1 year later, however, the bear had no signs of neurologic deficits.

Lumbosacral stenosis in dogs

Fifteen dogs with stenosis of the lumbosacral portion of the spinal canal were treated by laminectomy, bilateral facetectomy, and foraminotomy. Concomitant disk extrusion, spondylosis, fracture, infection, neoplasia, hemivertebrae, and spinal bifida were not associated with the stenosis and attendant cauda equina compression. The predominant neurologic signs were intermittent hindlimb lameness and motor weakness; hindlimb muscle atrophy; presumed paresthesia with resultant dermatologic manifestations from self mutilation of the hindlimbs, tail, perineum, anal area, and genitalia; urinaryu or fecal incontinence, or both; and consistently elicitable pain on manipulation of the lumbosacral spine. Surgical decompression of the stenotic canal alleviated the clinical signs in all cases.

Treatment of cervical vertebral instability in the dog

In a retrospective study, common neurologic signs and results of treatment of cervical vertebral instabilities were reviewed. In 16 large dogs, vertebrae C5 and C6 were most frequently malformed and unstable. Treatment was conservative in 3 dogs, 1 dog was not treated, and 12 dogs were treated surgically (dorsal decompressive laminectomy and wire stabilization of the articular facets in most cases). The 3 conservative treatments and 8 of the 12 surgical treatments were considered beneficial.

Dorsal laminectomy techniques in the dog

The effects of various lengths of complete dorsal laminectomy were compared with the effects of Funkquist method B laminectomy on the spinal cord of dogs. Complete dorsal laminectomies were done on L1 (group 1), L1 and L2 (group 2), and L1, L2, and L3 (group 3). Dogs of group 4 had Funkquist method B laminectomies on L1 and L2. Complete dorsal laminectomy on 1 vertebra and Funkquist method B laminectomy on 2 vertebrae did not result in any clinically untoward signs. In conjuction with these results, there was no dorsoventral flattening of the spinal cords and minimal microscopic damage within the spinal cords. If 2 or 3 vertebrae had a complete laminectomy, tonic spasticity of the pelvic limbs developed after surgery. Dorsoventral flattening of the spinal cord and moderate to severe microscopic damage were seen in the spinal cords of these dogs.

Clinical and histologic evaluation of bilateral hemilaminectomy and deep dorsal laminectomy for extensive spinal cord decompression in the dog

Various forms of 2 techniques for maximal decompression of the thoracolumbar spinal cord in dogs were evaluated clinically and histologically. Based on the results of this study, the veterinary surgeon could consider the following spinal decompression procedures: (1) deep dorsal laminectomy over 1 vertebra; (2) bilateral hemilaminectomy on 1 vertebra, with removal of articular processes and dorsal spinal plating; and (3) bilateral hemilaminectomy on 2 vertebrae, with the articular processes left intact. Of these 3, the 1st and 3rd techniques would probably be considered for use more often than the 2nd. Deep dorsal laminectomy over 2 vertebrae should be considered with reservation. Bilateral hemilaminectomy on 2 vertebrae, with rigid dorsal spinal plating and without articular processes at the ends of the defect, should not be used. Before using one of the techniques, the surgeon should consider the indications, advantages, and disadvantages for that technique.