Comparative study of bone repair in mandibular body osteotomy between metallic and absorbable 2.0 mm internal fixation systems. Histological and histometric analysis in dogs: a pilot study

The objective of this study was to compare the bone repair along a mandibular body osteotomy stabilized with 2.0 mm absorbable and metallic systems. 12 male, adult mongrel dogs were divided into two groups (metallic and absorbable) and subjected to unilateral osteotomy between the mandibular third and fourth premolars, which was stabilized by applying two 4-hole plates. At 2 and 18 weeks, three dogs from each group were killed and the osteotomy sites were removed and divided equally into three parts: the upper part was labelled the tension third (TT), the lower part the compression third (CT), and the part between the TT and CT the intermediary third (IT). Regardless of the treatment system, union between the fragments was observed at 18 weeks and the CT showed more advanced stages of bone repair than the TT. Histometric analysis did not reveal any significant differences among the 3 parts or systems in the distance between bone fragments at 2 weeks. Although at 18 weeks the proportions of newly formed bone did not differ among TT, IT and CT, significantly enhanced bone formation was observed in all sections for the metallic group. The patterns of repair were distinct between treatments.

Changes in tissue perfusion parameters in dogs with severe sepsis/septic shock in response to goal-directed hemodynamic optimization at admission to ICU and the relation to outcome

Objective To evaluate the changes in tissue perfusion parameters in dogs with severe sepsis/septic shock in response to goal-directed hemodynamic optimization in the ICU and their relation to outcome. Design Prospective observational study. Setting ICU of a veterinary university medical center. Animals Thirty dogs with severe sepsis or septic shock caused by pyometra who underwent surgery and were admitted to the ICU. Measurements and Main Results Severe sepsis was defined as the presence of sepsis and sepsis-induced dysfunction of one or more organs. Septic shock was defined as the presence of severe sepsis plus hypotension not reversed with fluid resuscitation. After the presumptive diagnosis of sepsis secondary to pyometra, blood samples were collected and clinical findings were recorded. Volume resuscitation with 0.9% saline solution and antimicrobial therapy were initiated. Following abdominal ultrasonography and confirmation of increased uterine volume, dogs underwent corrective surgery. After surgery, the animals were admitted to the ICU, where resuscitation was guided by the clinical parameters, central venous oxygen saturation (ScvO2), lactate, and base deficit. Between survivors and nonsurvivors it was observed that the ScvO2, lactate, and base deficit on ICU admission were each related independently to death (P = 0.001, P = 0.030, and P < 0.001, respectively). ScvO2 and base deficit were found to be the best discriminators between survivors and nonsurvivors as assessed via receiver operator characteristic curve analysis. Conclusion Our study suggests that ScvO2 and base deficit are useful in predicting the prognosis of dogs with severe sepsis and septic shock; animals with a higher ScvO2 and lower base deficit at admission to the ICU have a lower probability of death.

Early transplantation of human immature dental pulp stem cells from baby teeth to golden retriever muscular dystrophy (GRMD) dogs: Local or systemic?

Background:The golden retriever muscular dystrophy (GRMD) dogs represent the best available animal model for therapeutic trials aiming at the future treatment of human Duchenne muscular dystrophy (DMD). We have obtained a rare litter of six GRMD dogs (3 males and 3 females) born from an affected male and a carrier female which were submitted to a therapeutic trial with adult human stem cells to investigate their capacity to engraft into dogs muscles by local as compared to systemic injection without any immunosuppression. Methods Human Immature Dental Pulp Stem Cells (hIDPSC) were transplanted into 4 littermate dogs aged 28 to 40 days by either arterial or muscular injections. Two non-injected dogs were kept as controls. Clinical translation effects were analyzed since immune reactions by blood exams and physical scores capacity of each dog. Samples from biopsies were checked by immunohistochemistry (dystrophin markers) and FISH for human probes. Results and Discussion We analyzed the cells' ability in respect to migrate, engraftment, and myogenic potential, and the expression of human dystrophin in affected muscles. Additionally, the efficiency of single and consecutive early transplantation was compared. Chimeric muscle fibers were detected by immunofluorescence and fluorescent in situ hybridisation (FISH) using human antibodies and X and Y DNA probes. No signs of immune rejection were observed and these results suggested that hIDPSC cell transplantation may be done without immunosuppression. We showed that hIDPSC presented significant engraftment in GRMD dog muscles, although human dystrophin expression was modest and limited to several muscle fibers. Better clinical condition was also observed in the dog, which received monthly arterial injections and is still clinically stable at 25 months of age. Conclusion Our data suggested that systemic multiple deliveries seemed more effective than local injections. These findings open important avenues for further researches.

Influence of Durotomy on Laser-Doppler Measurement of Spinal Cord Blood Flow in Chondrodystrophic Dogs with Thoracolumbar Disk Extrusion

OBJECTIVES: To assess influence of durotomy on spinal cord blood flow (SCBF) in chondrodystrophic dogs with thoracolumbar disk extrusion. STUDY DESIGN: Prospective cohort study. ANIMALS: Chondrodystrophic dogs with thoracolumbar disk extrusion (n = 11). METHODS: Diagnosis was based on neurologic signs, magnetic resonance imaging (MRI) findings, and surgical confirmation. Regional SCBF was measured 3 times intraoperatively by laser-Doppler flowmetry: (1) before surgical decompression; (2) immediately after decompression by hemilaminectomy-durotomy; and (3) after 15 minutes of lesion lavage. A standardized hemilaminectomy and durotomy performed by the same neurosurgeon, was used to minimize factors that could influence measurement readings. RESULTS: A significant increase in intraoperative SCBF was found immediately after spinal cord decompression and durotomy in dogs but SCBF returned to previous levels or lower after 15 minutes of lavage. Changes in SCBF were not associated with duration of clinical signs; neurologic status, degree of spinal cord compression, or signal intensity changes as assessed by MRI. CONCLUSION: Durotomy does not increase SCBF in dogs with disk extrusion associated spinal cord compression.

Use of a 1.5 mm butterfly locking plate for stabilization of atlantoaxial pathology in three toy breed dogs

The objective of this study was to describe the use of a titanium 1.5 mm locking plate in the stabilization of atlantoaxial pathology in three toy breed dogs. Two dogs with atlantoaxial subluxation and another dog with an axial fracture, confirmed by diagnostic imaging, were stabilized via a ventral approach with a 1.5 mm titanium 5-hole locking butterfly-plate. Surgical reduction and stabilization were assessed by computed tomography and radiography after surgery. Follow-up evaluation for resolution of neurological signs and possible complications was performed in all three dogs. For long-term assessment, a telephone follow-up was performed. A considerable improvement of neurological signs occurred within two to four weeks after surgery. An excellent clinical outcome was identified in all three patients. Adequate stabilization and resolution of neurological signs in all three dogs was achieved. The stabilization of atlantoaxial surgical conditions in toy breeds with the 1.5 mm titanium 5-hole butterfly locking plate appears to be an effective means of surgical treatment.

Microfenestration using the CUSA Excel ultrasonic aspiration system in chondrodystrophic dogs with thoracolumbar disk extrusion: a descriptive cadaveric and clinical study

OBJECTIVE: To describe an ultrasonic surgical aspirator assisted disk fenestration technique in dogs. STUDY DESIGN: Descriptive cadaveric and prospective clinical study. ANIMALS: Fresh Beagle cadavers (n=5) and 10 chondrodystrophic dogs with thoracolumbar disk extrusion. METHODS: Cadaveric study: Intervertebral disks T12-L2 were fenestrated with the CUSA Excel in 5 Beagle cadavers, and fenestration efficacy assessed by morphologic examination of the completeness of fenestration and size of annulotomy. Clinical study: the affected intervertebral disk was fenestrated in 10 chondrodystrophic dogs treated by hemilaminectomy for thoracolumbar disk disease. Efficacy of fenestration was evaluated. RESULTS: Mean time necessary to perform CUSA assisted fenestration was 8 minutes (range, 5-10 minutes) for each disk in cadavers and patients. In cadaver spines, removal of the nucleus pulposus was complete in 11/15 disks. In 4 disks, remnants of nucleus pulposus material were observed on the contralateral side. Nuclear material was normal in 9/15 disks and showed evidence of chondroid degeneration on histopathologic examination in the 6 disks. Median annulotomy size was 3 mm. Clinically, no signs of early recurrence were observed and all dogs recovered uneventfully. CONCLUSIONS: CUSA assisted fenestration is a safe and efficient method of fenestration for removal of most of the nucleus pulposus through a limited annulotomy.

Ground reaction force profiles after partial and pancarpal arthrodesis in dogs

OBJECTIVES: To evaluate and compare long-term functional outcome after partial carpal arthrodesis and pancarpal arthrodesis in dogs using kinetic gait analysis. METHODS: Fourteen dogs with 19 partial carpal or pancarpal arthrodeses were retrospectively examined and underwent force-plate gait analysis. Mean times since surgery were 29.4 and 24.4 months for pancarpal and partial carpal arthrodesis respectively. Vertical and braking-propulsive ground reaction force profiles were compared between treatment groups, and to those of normal dogs (control group) using Kruskal-Wallis one-way analysis of variance. RESULTS: With the exception of time to vertical peak that occurred earlier in dogs with pancarpal than in dogs with partial carpal arthrodesis (p <0.01), there was no difference between the two treatment groups. Several parameters differed significantly between operated and healthy dogs (p <0.01): vertical impulses were significantly lower in both treatment groups, braking forces and impulses were also reduced after both techniques. Propulsive forces and impulses were only reduced in dogs with pancarpal arthrodesis. When comparing gait parameters of sound limbs of unilateral operated dogs to those of control dogs, braking forces and impulses (p <0.01; p <0.05) were significantly higher in the sound legs of unilateral operated dogs. CLINICAL SIGNIFICANCE: Long-term outcome after partial carpal and pancarpal arthrodesis is good and comparable to each other. Propulsive action may be altered more in dogs with pancarpal arthrodesis.

Incidence of spinal compressive lesions in chondrodystrophic dogs with abnormal recovery after hemilaminectomy for treatment of thoracolumbar disc disease: a prospective magnetic resonance imaging study

OBJECTIVE: To investigate causes of the lack of clinical improvement after thoracolumbar disc surgery. STUDY DESIGN: Case-control magnetic resonance imaging (MRI) study. ANIMALS: Chondrodystrophic dogs with acute thoracolumbar disc disease treated by hemilaminectomy: 10 that had no short-term clinical improvement and 12 with "normal" clinical improvement. METHODS: Dogs that had surgery for treatment of intervertebral disc extrusion (2003-2008) where thoracolumbar disc disease was confirmed by MRI were evaluated to identify dogs that had lack of clinical improvement after surgery. Ten dogs with delayed recovery or clinical deterioration were reexamined with MRI and compared with 12 dogs with normal recovery and MRI reexamination after 6 weeks (control group). RESULTS: Of 173 dogs, 10 (5.8%) had clinical deterioration within 1-10 days after surgery. In 8 dogs, residual spinal cord compression was identified on MRI. Bleeding was present in 1 dog. In 3 dogs, the cause was an incorrect approach and insufficient disc material removal. In 3 dogs, recurrence occurred at the surgical site. In 1 dog, the centrally located extruded material was shifted to the contralateral side during surgery. These 8 dogs had repeat surgery and recovery was uneventful. In 2 dogs, deterioration could not be associated with a compressive disc lesion. Hemorrhagic myelomalacia was confirmed by pathologic examination in 1 dog. The other dog recovered after 6 months of conservative management. CONCLUSION: Delayed postsurgical recovery or deterioration is commonly associated with newly developed and/or remaining compressive disc lesion. CLINICAL RELEVANCE: We recommend early MRI reexamination to assess the postsurgical spinal canal and cord, and to plan further therapeutic measures in chondrodystrophic dogs with delayed recovery after decompressive hemilaminectomy for thoracolumbar disc disease.

Low-field Mri and arthroscopy of meniscal lesions in ten dogs with experimentally induced cranial cruciate ligament insufficiency

Little is known about the magnetic resonance imaging (MRI) appearance of canine meniscal lesions. The aim of this study is to describe the MR appearance of meniscal lesions in dogs with experimentally induced cranial cruciate ligament (CCL) deficiency. The pilot study revealed dogs weighing approximately 10 kg to be too small for meniscal evaluation on low-field MRI. In the main study, dogs weighing approximately 35 kg were used. The left CCL was transected and low-field MRI was performed regularly until 13 months post-surgery. Normal menisci were defined as grade 0. Intrameniscal lesions not reaching any surface corresponded to grade 1 if focal and to grade 2 if linear or diffuse. Grade 3 lesions consisted in linear tears penetrating a meniscal surface. Grade 4 lesions included complex signal changes or meniscal distortion. Between 2 and 13 months post-surgery, all dogs developed grade 4 lesions in the medial meniscus. Most of them corresponded to longitudinal or bucket handle tears on arthroscopy and necropsy. Two dogs showed grade 3 lesions reaching the tibial surface of the lateral meniscus on MRI but not in arthroscopy. Such tears are difficult to evaluate arthroscopically; MRI provides more accurate information about the tibial meniscal surface. Grades 1 and 2 lesions could not be differentiated from presumably normal menisci with our imaging technique. An MRI grading system better adapted to canine lesions has yet to be developed. MRI is a helpful tool for the diagnosis of complete tears in the canine meniscus, especially in larger dogs.

Synovial cysts associated with cauda equina syndrome in two dogs

OBJECTIVE: To report synovial cysts associated with cauda equina syndrome in 2 dogs. STUDY DESIGN: Clinical cases. ANIMALS: Two German Shepherd dogs. METHODS: After magnetic resonance imaging detection, cysts were surgically removed via dorsal laminectomy. RESULTS: Six and 8 months after surgery, both dogs were free of clinical signs and no pain was elicited on lumbosacral joint manipulation. CONCLUSION: Although described in dogs, cysts at the lumbosacral joint might cause compression of the cauda equina nerve roots. Radical excision of the cyst capsule can result in resolution of clinical signs. CLINICAL RELEVANCE: Synovial cysts should be considered in the differential diagnosis of dogs with cauda equina compression syndrome when lumbosacral degenerative joint disease is present.

Thoracolumbar dorsolateral laminectomy with osteotomy of the spinous process in fourteen dogs

OBJECTIVE: To describe outcome after an alternative unilateral approach to the thoracolumbar spine for dorsal laminectomy. STUDY DESIGN: Retrospective clinical study. ANIMALS: Dogs (n=14) with thoracolumbar spinal cord compression. METHODS: Thoracolumbar spinal cord compression was lateral (6 dogs), dorsal (4), and dorsolateral (4) caused by subarachnoid (7) and synovial cysts (2) and intradural-extramedullary neoplasia (5). All dogs were treated by dorsal laminectomy with osteotomy of the spinous process using a unilateral paramedian approach. The contralateral paraspinal muscles were not stripped from the spinous process and the osteoligamentous complexes were preserved. Retraction of the spinous process and muscles to the contralateral side resulted in complete visualization of the dorsal vertebral arch thereby allowing dorsal laminectomy to be performed. RESULTS: No technique complications occurred. Approximately 75% exposure of the spinal cord (dorsal and lateral compartments) was achieved providing adequate visualization and treatment of the lesions. Transient deterioration of neurologic state occurred in 5 dogs because of extensive spinal cord manipulation. At long-term follow-up, 6 dogs were normal, 6 had clinical improvement, and 2 were unchanged. CONCLUSION: Dorsal laminectomy after osteotomy and retraction of the spinous process may be considered in canine patients with dorsal, dorsolateral, or lateral compression to facilitate adequate decompression of the spinal cord. CLINICAL SIGNIFICANCE: This surgical technique offers an alternative approach to the thoracolumbar spine and spinal cord by a modified dorsal laminectomy that preserves the paraspinal muscle integrity on the contralateral side.

Iatrogenic sciatic nerve injury in eighteen dogs and nine cats (1997-2006)

OBJECTIVE: To report clinical features associated with iatrogenic peripheral nerve injury in dogs and cats admitted (1997-2006) to a referral teaching hospital. STUDY DESIGN: Retrospective study. ANIMALS: Dogs (n=18), 9 cats. METHODS: Patients had acute signs of monoparesis attributable to sciatic nerve dysfunction that developed after treatment. Neurologic examination and electrodiagnostic testing were performed. Surgical therapy was used for nerve entrapment and delayed reconstructive surgery used in other cases. RESULTS: Of 27 nerve injuries, 25 resulted from surgery (18 with treatment of pelvic injuries). Iliosacral luxation repair resulted in tibial (4 cats) and peroneal (3 dogs) nerve dysfunction. Other causes were intramedullary pinning of femoral fractures (3), other orthopedic surgery (cemented hip prosthesis [2] and tibial plateau-leveling osteotomy [1]), and perineal herniorrhaphy [1]. Nerve injury occurred after intramuscular injection (1 cat, 1 dog). Immediate surgical treatment was removal of intramedullary nails, extruded cement, or entrapping suture. Delayed nerve transplantation was performed in 2 dogs. Within 1 year, 13 patients recovered completely, clinical improvement occurred in 7, and there was no improvement in 7. Five of the 7 dogs that did not recover had acetabular or ilium fracture. CONCLUSION: Iatrogenic sciatic nerve injury occurred most commonly during treatment of pelvic orthopedic diseases and had a poor prognosis. Clinical variation in sciatic nerve dysfunction in dogs and cats can be explained by species anatomic differences. CLINICAL RELEVANCE: Iatrogenic sciatic nerve injury leads to severely debilitating locomotor dysfunction with an uncertain prognosis for full-functional recovery.

Ventral intraspinal cysts associated with the intervertebral disc: magnetic resonance imaging observations in seven dogs

OBJECTIVE: To report clinical and diagnostic imaging features, and outcome after surgical treatment of ventral intraspinal cysts in dogs. STUDY DESIGN: Retrospective study. ANIMALS: Dogs (n=7) with ventral intraspinal cysts. METHODS: Clinical signs, magnetic resonance imaging (MRI) findings and surgical findings of 7 dogs and histologic findings (1 dog) with intraspinal cysts associated with the intervertebral disc were reviewed. RESULTS: Ventral intraspinal cyst is characterized by: (1) clinical signs indistinguishable from those of typical disc herniation; (2) an extradural, round to oval, mass lesion with low T1 and high T2 signal intensity on MRI, compatible with a liquid-containing cyst; (3) cyst is in close proximity to the intervertebral disc; and (4) MRI signs of disc degeneration. Although the exact cause is unknown, underlying minor disc injury may predispose to cyst formation. CONCLUSION: Intraspinal cysts have clinical signs identical to those of disc herniation. Given the close proximity of the cyst to the corresponding disc and the similarity of MRI findings to discal cysts in humans, we propose the term "canine discal cyst" to describe this observation. CLINICAL RELEVANCE: Discal cysts should be considered in the differential choices for cystic extradural compressing lesions.

Morphogenesis of the peri-implant mucosa: an experimental study in dogs

PURPOSE: The objective of the present experiment was to study the morphogenesis of the mucosal attachment to implants made of c.p. titanium. MATERIAL AND METHODS: All mandibular premolars were extracted in 20 Labrador dogs. After a healing period of 3 months, four implants (ITI Dental Implant System) were placed in the right and left sides of the mandible. A non-submerged implant installation technique was used and the mucosal tissues were secured to the conical marginal portion of the implants with interrupted sutures. The sutures were removed after 2 weeks and a plaque control program including daily cleaning of the remaining teeth and the implants was initiated. The animals were sacrificed and biopsies were obtained at various intervals to provide healing periods extending from Day 0 (2 h) to 12 weeks. The mandibles were removed and placed in the fixative. The implant sites were dissected using a diamond saw and processed for histological analysis. RESULTS: Large numbers of neutrophils infiltrated and degraded the coagulum that occupied the compartment between the mucosa and the implant during the initial phase of healing. At 2 weeks after surgery, fibroblasts were the dominating cell population in the connective tissue interface but at 4 weeks the density of fibroblasts had decreased. Furthermore, the first signs of epithelial proliferation were observed in specimens representing 1-2 weeks of healing and a mature barrier epithelium occurred after 6-8 weeks of healing. The collagen fibers of the mucosa were organized after 4-6 weeks of healing. CONCLUSION: It is suggested that the soft-tissue attachment to implants placed using a non-submerged installation procedure is properly established after several weeks following surgery.

Biomechanical analysis of torsion and shear forces in lumbar and lumbosacral spine segments of nonchondrodystrophic dogs

OBJECTIVE: To determine stiffness and load-displacement curves as a biomechanical response to applied torsion and shear forces in cadaveric canine lumbar and lumbosacral specimens. STUDY DESIGN: Biomechanical study. ANIMALS: Caudal lumbar and lumbosacral functional spine units (FSU) of nonchondrodystrophic large-breed dogs (n=31) with radiographically normal spines. METHODS: FSU from dogs without musculoskeletal disease were tested in torsion in a custom-built spine loading simulator with 6 degrees of freedom, which uses orthogonally mounted electric motors to apply pure axial rotation. For shear tests, specimens were mounted to a custom-made shear-testing device, driven by a servo hydraulic testing machine. Load-displacement curves were recorded for torsion and shear. RESULTS: Left and right torsion stiffness was not different within each FSU level; however, torsional stiffness of L7-S1 was significantly smaller compared with lumbar FSU (L4-5-L6-7). Ventral/dorsal stiffness was significantly different from lateral stiffness within an individual FSU level for L5-6, L6-7, and L7-S1 but not for L4-5. When the data from 4 tested shear directions from the same specimen were pooled, level L5-6 was significantly stiffer than L7-S1. CONCLUSIONS: Increased range of motion of the lumbosacral joint is reflected by an overall decreased shear and rotational stiffness at the lumbosacral FSU. CLINICAL RELEVANCE: Data from dogs with disc degeneration have to be collected, analyzed, and compared with results from our chondrodystrophic large-breed dogs with radiographically normal spines.