Dog Spinal Cord Research Articles

Aberrant migration of Spirocerca Lupi to the spinal cord in dogs: Association of clinical signs, CSF analysis, preventive treatment, and outcome.

Spirocerca lupi is a nematode typically targeting the esophageal wall but may also migrate to the spinal cord. This study aimed to characterize the clinical presentation, cerebrospinal fluid (CSF) findings, prognostic factors, and outcomes of dogs with spinal S. lupi (SSL) aberrant migration, and to evaluate prophylactic treatment efficacy. Medical records from 2016 to 2022 were reviewed, including 284 study and 280 control dogs. Complete recovery occurred in 130/284 dogs (46 %) at 1 month, and in 214/284 dogs (75 %) at 3 months and was associated with the clinical grade at presentation (P < 0.001). Of the 162 non-ambulatory dogs, 59 % became ambulatory at 1 month, and 79 % at 3 months. Dogs with urinary incontinence were less likely to fully recover (P = 0.04). Protein CSF concentration was lower at presentation in dogs who completely recovered at 1 month and 3 months (344 mg/dL [15-1297] vs. 732 mg/dL [34-1291], P = 0.006, and 366 mg/dL [15-1297] vs. 769 mg/dL [83-1262], P = 0.025, respectively). A higher proportion of control dogs received prophylactic treatment compared to the SSL group (168/284 [59 %] vs. 216/280 [77 %], respectively, P < 0.001, OR 0.43, CI 0.30-0.62) however, prophylactic treatment did not significantly impact recovery rates. Our findings suggest that SSL is associated with a favorable prognosis; however, full recovery may take several months, and dogs presenting with urinary incontinence and higher neurological severity grades are less likely to recover. Finally, our findings suggest that prophylactic treatment against S. lupi may have a protective effect against SSL and is therefore recommended in endemic regions.

Effects of remifentanil on the noxiously stimulated somatosensory evoked potentials recorded at the spinal cord in dogs and cats

This study assessed the somatosensory evoked potentials (SEPs) in dogs and cats to compare the effect of remifentanil on the action potentials evoked by peripheral noxious stimulation in the spinal cord. Five healthy dogs and five healthy cats underwent general anaesthesia induced with propofol and maintained with isoflurane. Each animals received all dosage of a constant-rate infusion of remifentanil at 0 (control), 0.25, 0.5, 1.0 or 2.0 μg/kg/min. The hair of the dorsal foot of a hind limb was clipped and an intraepidermal stimulation electrode that could selectively stimulate the nociceptive Aδ and C fibres was attached. An electrical stimulus was generated by a portable peripheral nerve testing device. The evoked potentials were recorded by two needle electrodes inserted subcutaneously in the dorsal midline between the lumbar vertebra: L3-L4 and L4-L5. Bimodal waveforms were obtained by electrical stimulation in control dogs and cats. The inhibitory effect of remifentanil was evaluated by comparing the changes in the N1P2 and P2N2 amplitudes. The N1P2 amplitude was depressed by remifentanil in a dose-dependent manner in dogs, but it showed no remifentanil-induced changes in cats. While the P2N2 amplitude was also depressed in a dose-dependent manner in dogs, it showed milder remifentanil-induced effects in cats. The N1P2 and P2N2 amplitudes observed herein are assumed to represent the evoked potentials derived from the Aδ and C fibres, respectively. Thus, the inhibitory effect of remifentanil on nociceptive transmission at the spinal cord was much weaker in cats, especially for transmissions possibly derived from Aδ fibres.

DEGENERATIVE DISEASES OF THE INTERVERTEBRAL DISC IN DOGS OF HOME LIVING CONDITIONS

To date, degenerative diseases of the intervertebral discs in dogs of chondrodystrophoid breeds, such as dachshunds, French bulldogs, pugs, corgis, etc., is one of the most pressing problems, as these breeds are becoming increasingly popular, and there are more opportunities for the diagnosis and treatment of this disease. The purpose of our study was to study the course of neurological pathological processes that occur as a result of compression on the spinal cord in dogs of different ages in home conditions.The study involved 20 dogs of different ages with clinical signs characteristic of the disease, the focus of which is localized in the spinal column. Clinical signs were expressed in paresis or plegia of the pelvic or all extremities, ataxia, absence of deep pain sensitivity. Based on the anamnesis data and specific findings during the examination, all patients were recommended to undergo magnetic resonance imaging of certain segments of the spinal column with intravenous administration of a contrast agent. As a result of our studies, extrusions (Hansen 1) were detected in almost all dogs, and in 60% of cases the lesion was located between the 3rd thoracic and 3rd lumbar vertebra, which was indicated by certain symptoms and subsequently by MRI.

Diagnosis and treatment of autoimmune diseases of the brain and spinal cord in dogs: analysis of the literature review

The main methods of diagnosing these diseases, according to the analysis of world literature data, are the analysis of the patient's cerebrospinal fluid and magnetic resonance imaging (MRI). The analysis of cerebrospinal fluid (CSF) is carried out in order to detect changes characteristic of the diagnosis. With the help of MRI, it is possible to determine the localization of inflammation. A number of studies have been aimed at improving diagnostic methods by detecting new factors characteristic of autoimmune diseases of the nervous system. Data on the detection of antibodies corresponding to human antibodies in the cerebrospinal fluid of dogs and on changes in the concentration of various substances in it are presented. This allows for faster and more accurate diagnostics.As a result of the generalization of the literature data, it was found that immunosuppressive drugs are used for the treatment of autoimmune diseases of the brain and spinal cord of dogs. According to the data presented, the most effective of the known methods of treatment of autoimmune meningoencephalitis is the use of a combination of prednisolone and imatinib mesylate. For the treatment of steroid-dependent meningoarteritis (SRMA), various corticosteroid drugs are used, the most optimal of which is the combination of prednisone and cytarabine.The purpose of our study was to study modern Russian and foreign literature sources on autoimmune diseases of the brain and spinal cord in dogs, methods of diagnosis and treatment of these diseases and to review works that provide new data on their treatment, diagnosis and understanding of etiology and pathogenesis.

Materials for the study of secondary degeneration in the spinal cord after transverse injuries

All my experiments were carried out on dogs. I stopped at these animals in view of the fact that in terms of topographic relations, their spinal cord is closer to the human; this circumstance gives more guarantees not to fall into a gross error when comparing the results obtained with those of people. At the same time, only adult dogs were taken for the experiments, in which the process of development of the central nervous system could be considered completely complete. This condition was essential for my goals, since I set myself the task of studying secondary regeneration on fully developed brains. In addition, the question of the beginnings and consistency of the development of secondary degenerations of individual systems in the spinal cord of dogs, specially put into the program of my study, also required the observance of the indicated conditions.

Reduced field-of-view diffusion-weighted MRI can identify restricted diffusion in the spinal cord of dogs and cats with presumptive clinical and high-field MRI diagnosis of acute ischemic myelopathy.

Diffusion-weighted imaging MRI is the gold standard imaging technique for diagnosis of suspected acute brain ischemia in dogs and cats; however, it is technically challenging to apply to spinal cord imaging, due to its very small size, the inherent low spatial resolution of diffusion-weighted imaging, and the marked distortion resulting from magnetic field inhomogeneities caused by the osseous components of the vertebral column surrounding the spinal cord. Ischemic myelopathy is a common cause of acute non-compressive myelopathy in dogs and cats. Technological improvement in diffusion-weighted imaging pulse sequences allow imaging at smaller field of view with better spatial resolution and less image distortion. We sought to evaluate reduced field-of-view diffusion-weighted imaging MRI using a dedicated proprietary pulse sequence (FOCUS, General Electric) in a small sample of dogs and cats with a presumptive clinical and MRI diagnosis of acute ischemic myelopathy that were imaged with this pulse sequence. Five dogs and two cats fitted these inclusion criteria. In all of them, hyperintense spinal cord parenchyma signal was seen on diffusion-weighted imaging images corresponding to decreased signal on apparent diffusion coefficient map indicative of restricted diffusion, consistent with ischemia and cytotoxic edema. These areas matched the areas of abnormal T2-weighted signal and cord swelling observed on conventional spinal MRI. This small exploratory descriptive study indicates feasibility and possible usefulness of reduced field-of-view diffusion-weighted imaging MRI in dogs and cats with suspected acute ischemic myelopathy and that it may be added to the imaging protocol of the spine in such patients in an appropriate clinical setting.

F-wave parameters for the tibial nerve in Miniature Dachshunds with and without naturally acquired thoracolumbar intervertebral disk herniation.

To determine values of F-wave parameters for the tibial nerve in clinically normal Miniature Dachshunds and those with thoracolumbar intervertebral disk herniation (IVDH). 53 Miniature Dachshunds (10 clinically normal and 43 with various clinical grades of thoracolumbar IVDH). F-waves were elicited in the interosseous muscles of 1 hind limb in each dog by stimulation of the tibial nerve. F-wave parameters were measured for 32 stimuli/dog, and mean values were calculated. Linear regression was performed to assess correlations between F-wave parameters and clinical severity of IVDH. For clinically normal dogs, mean ± SD values of shortest F-wave latency, mean F-wave conduction velocity, mean F-wave duration, and ratio of the mean F-wave amplitude to M response amplitude were 8.6 ± 0.6 milliseconds, 83.7 ± 6.1 m/s, 6.6 ± 1.5 milliseconds, and 9.8 ± 8.5%, respectively. F-wave persistence was 100%. Mean F-wave duration was positively correlated with clinical grade of IVDH. Linear regression yielded the following regression equation: F-wave duration (milliseconds) = 6.0 + 2.7 × IVDH grade. One dog with grade 2 IVDH had a mean F-wave duration shorter than that of all 5 dogs with grade 1 IVDH; 1 dog with grade 3 IVDH had a longer duration than that of all 10 dogs with grade 4 IVDH. Mean F-wave duration was correlated with the severity of inhibitory motor tract dysfunction in the spinal cord of dogs. F-wave examination may be useful for objective functional evaluation of upper motor neurons in the spinal cord.

Minimally invasive spine surgery in dogs: Evaluation of the safety and feasibility of a thoracolumbar approach to the spinal cord.

To describe the safety and feasibility of a minimally invasive spine surgery technique to access the thoracolumbar vertebral canal in dogs. Prospective study. Six healthy research dogs. Dogs were placed under anesthesia for MRI to evaluate vertebral column and spinal cord integrity. Minimally invasive surgery was performed at multiple sites. Access to the vertebral canal was achieved by means of foraminotomy, discectomy, and lateral minicorpectomy by using minimally invasive access and a surgical microscope. Sequential neurological examinations, pressure algometry pain quantification, and creatine kinase levels were evaluated before and after surgery for 7 days. Magnetic resonance imaging, computed tomography, and histopathology were performed on day 6 postoperatively after animals were humanely killed to evaluate the impact of surgery on spinal cord, muscles, and bone. The vertebral canal was successfully accessed, and the ventral aspect of the spinal cord was identified at all sites. No neurological deterioration was observed. Postoperative pain was not different compared with baseline except in one dog on the day after surgery. Minimally invasive spine surgery was a safe and feasible technique to access the thoracolumbar vertebral canal and the ventral aspect of the spinal cord in dogs. Findings supported postoperative pain benefits. Minimally invasive spine surgery is a valid surgical technique to access the thoracolumbar vertebral canal at single or multiple sites in dogs.

Lumbar spinal cord microglia exhibited increased activation in aging dogs compared with young adult dogs.

Altered microglia function contributes to loss of CNS homeostasis during aging in the brain. Few studies have evaluated age-related alterations in spinal cord microglia. We previously demonstrated that lumbar spinal cord microglial expression of inducible nitric oxide synthase (iNOS) was equivalent between aging, neurologically normal dogs and dogs with canine degenerative myelopathy (Toedebusch et al. 2018, Mol Cell Neurosci. 88, 148-157). This unexpected finding suggested that microglia in aging spinal cord have a pro-inflammatory polarization. In this study, we reexamined our microglial results (Toedebusch et al. 2018, Mol Cell Neurosci. 88, 148-157) within the context of aging rather than disease by comparing microglia in aging versus young adult dogs. For both aging and young adult dogs, the density of microglia was significantly higher closest to the motor neuron cell body. However, there was no difference in densities between aging versus young adult dogs at all distances except for the furthest distance analyzed. The number of motor neurons with polarized microglia was higher in aging dogs; yet, the density per motor neuron of arginase-1-expressing microglia was reduced in aging dogs compared with young adult dogs. Finally, aging dogs had increased steady-state mRNA levels for genes consistent with activated microglia compared with young adult dogs. However, altered mRNA levels were limited to the lumbar spinal cord. These data suggested that aging dog spinal cord microglia exhibit regional immunophenotypic differences, which may render lumbar motor neurons more susceptible to age-related pathological insults.

ЛІКУВАННЯ СОБАК З УРАХУВАННЯМ ОСОБЛИВОСТЕЙ ПАТОГЕНЕЗУ ХРЕБЕТНО-СПИННОМОЗКОВИХ ТРАВМ

ЛІКУВАННЯ СОБАК З УРАХУВАННЯМ ОСОБЛИВОСТЕЙ ПАТОГЕНЕЗУ ХРЕБЕТНО-СПИННОМОЗКОВИХ ТРАВМ

Permeability of the Dura Mater of the Spinal Cord in Dogs for Low Molecular Weight Substances in Serum

The permeability of the dura mater (DM) of the dog spinal cord for low molecular weight serum components – urea, creatinine, glucose, lactate, cholesterol, calcium, and inorganic phosphate – was studied in in vitro conditions. DM permeability for a high molecular weight serum component – albumin – was assessed as a reference compound. Most of the study components had permeabilities of 8–15%. The greatest DM permeability was for lactate (33.6%) and the lowest was for cholesterol (1.3%). Values for urea and creatinine were 8.0 and 7.5%, respectively; there was a nonlinear relationship between permeability and the initial substrate concentration in the serum. The DM permeability threshold for urea was 4.83 mM and that for creatinine was 97 μM. The functional characteristics of DM permeability may be determined by its structural features – dense packing of fibrillar connective tissues structures, high content of sulfated and the absence of nonsulfated glycosaminoglycans.

Upregulation of CB2 receptors in reactive astrocytes in canine degenerative myelopathy, a disease model of amyotrophic lateral sclerosis.

ABSTRACTTargeting of the CB2 receptor results in neuroprotection in the SOD1G93A mutant mouse model of amyotrophic lateral sclerosis (ALS). The neuroprotective effects of CB2 receptors are facilitated by their upregulation in the spinal cord of the mutant mice. Here, we investigated whether similar CB2 receptor upregulation, as well as parallel changes in other endocannabinoid elements, is evident in the spinal cord of dogs with degenerative myelopathy (DM), caused by mutations in the superoxide dismutase 1 gene (SOD1). We used well-characterized post-mortem spinal cords from unaffected and DM-affected dogs. Tissues were used first to confirm the loss of motor neurons using Nissl staining, which was accompanied by glial reactivity (elevated GFAP and Iba-1 immunoreactivity). Next, we investigated possible differences in the expression of endocannabinoid genes measured by qPCR between DM-affected and control dogs. We found no changes in expression of the CB1 receptor (confirmed with CB1 receptor immunostaining) or NAPE-PLD, DAGL, FAAH and MAGL enzymes. In contrast, CB2 receptor levels were significantly elevated in DM-affected dogs determined by qPCR and western blotting, which was confirmed in the grey matter using CB2 receptor immunostaining. Using double-labelling immunofluorescence, CB2 receptor immunolabelling colocalized with GFAP but not Iba-1, indicating upregulation of CB2 receptors on astrocytes in DM-affected dogs. Our results demonstrate a marked upregulation of CB2 receptors in the spinal cord in canine DM, which is concentrated in activated astrocytes. Such receptors could be used as a potential target to enhance the neuroprotective effects exerted by these glial cells.

Diffusion tensor imaging of white and grey matter within the spinal cord of normal Beagle dogs: Sub-regional differences of the various diffusion parameters

Diffusion tensor imaging (DTI) is an advanced diffusion weighted imaging technique that can identify early stage lesions and Wallerian degeneration within the spinal cord; these changes are difficult to recognise on conventional magnetic resonance imaging (MRI). The only DTI parameters previously investigated in dogs are fractional anisotropy and mean diffusivity (MD). The aim of this study was to evaluate multiple DTI parameters in sub-regional areas of the spinal cord in normal Beagles. All imaging data were obtained from the lumbar spinal cord (L1–L3) of ten normal dogs using a 3 Tesla MRI scanner. Transverse multi-shot echo planar imaging sequences (b values = 0 and 800 s/mm2; 12 directions) were used for DTI. Regions of interest were selected from sub-regions of the white and grey matter, and from the whole spinal cord, in the transverse plane in all DTI maps. The DTI parameters in spinal cord sub-regions in the transverse plane were significantly different amongst the white matter, grey matter and whole spinal cord (P < 0.05 for all DTI parameters except MD), as well as between white matter sub-regions (P < 0.05 for most DTI parameters except radial diffusivity, MD and planar index). DTI-based sub-regional analysis of white and grey matter may be useful for regional evaluation of the dog spinal cord.

Feasibility Study of Canine Epidermal Neural Crest Stem Cell Transplantation in the Spinal Cords of Dogs.

This pilot feasibility study aimed to determine the outcome of canine epidermal neural crest stem cell (cEPI-NCSC) grafts in the normal spinal cords of healthy bred-for-research dogs. This included developing novel protocols for (a) the ex vivo expansion of cEPI-NCSCs, (b) the delivery of cEPI-NCSCs into the spinal cord, and (c) the labeling of the cells and subsequent tracing of the graft in the live animal by magnetic resonance imaging. A total of four million cEPI-NCSCs were injected into the spinal cord divided in two locations. Differences in locomotion at baseline and post-treatment were evaluated by gait analysis and compared with neurological outcome and behavioral exams. Histopathological analyses of the spinal cords and cEPI-NCSC grafts were performed at 3 weeks post-transplantation. Neurological and gait parameters were minimally affected by the stem cell injection. cEPI-NCSCs survived in the canine spinal cord for the entire period of investigation and did not migrate or proliferate. Subsets of cEPI-NCSCs expressed the neural crest stem cell marker Sox10. There was no detectable expression of markers for glial cells or neurons. The tissue reaction to the cell graft was predominantly vascular in addition to a degree of reactive astrogliosis and microglial activation. In the present study, we demonstrated that cEPI-NCSC grafts survive in the spinal cords of healthy dogs without major adverse effects. They persist locally in the normal spinal cord, may promote angiogenesis and tissue remodeling, and elicit a tissue response that may be beneficial in patients with spinal cord injury. It has been established that mouse and human epidermal neural crest stem cells are somatic multipotent stem cells with proved innovative potential in a mouse model of spinal cord injury (SCI) offering promise of a valid treatment for SCI. Traumatic SCI is a common neurological problem in dogs with marked similarities, clinically and pathologically, to the syndrome in people. For this reason, dogs provide a readily accessible, clinically realistic, spontaneous model for evaluation of epidermal neural crest stem cells therapeutic intervention. The results of this study are expected to give the baseline data for a future clinical trial in dogs with traumatic SCI.

Mielografia lombar no diagnóstico de extrusão do disco intervertebral toracolombar em cães: estudo prospectivo

Thoracolumbar disk extrusion is the most common cause of extradural compression of the spinal cord in dogs. Myelography is one of the most commonly performed techniques for the diagnosis of this affection. This study aimed to evaluate the applicability and effectiveness of lumbar myelography in the diagnosis of thoracolumbar intervertebral disk extrusion in dogs, as well as its major complications. Twenty dogs were used in this study. Animals were included when neurological examination suggested thoracolumbar spine lesion, myelography was used as a complementary diagnostic method, and diagnosis of disk extrusion was surgically confirmed. The accuracy of the exam to predict location and lateralization of extruded disk material were evaluated, as well as complications associated to the procedure. Lumbar myelography exhibited 95% and 60% accuracy for location and lateralization of the lesion, respectively, with minimal complications.

Quantitative assessment of hsp70, IL-1β and TNF-α in the spinal cord of dogs with E40K SOD1-associated degenerative myelopathy

Inflammation is involved in the pathogenesis of many neurodegenerative diseases. Canine degenerative myelopathy (DM) is a progressive adult-onset neurodegenerative disease commonly associated with an E40K missense mutation in the SOD1 gene. DM has many similarities to some familial forms of human amyotrophic lateral sclerosis (ALS) and may serve as an important disease model for therapy development. Pro-inflammatory mediators such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α and heat shock protein (hsp) 70 play a role in the pathogenesis of ALS. The focus of the current work was to determine whether an inflammatory phenotype is present in canine DM as defined by IL-1β, TNF-α, and hsp70 responses in cerebrospinal fluid (CSF) and spinal cord tissue. Concentrations of hsp70, IL-1β and TNF-α were below the limits of detection by ELISA in the CSF of both normal and DM-affected dogs. Immunohistochemical staining for hsp70 was significantly increased in ependymal cells lining the spinal cord central canal of DM-affected dogs (P = 0.003). This was not associated with increased IL-1β or TNF-α staining, but was associated with increased CD18 staining in the gray matter of DM-affected dogs. These results suggest that hsp70 in spinal cord tissue is a potential inflammatory signature in canine DM.

Use of autologous mesenchymal stem cells derived from bone marrow for the treatment of naturally injured spinal cord in dogs.

The use of stem cells in injury repair has been extensively investigated. Here, we examined the therapeutic effects of autologous bone marrow mesenchymal stem cells (MSC) transplantation in four dogs with natural traumatic spinal cord injuries. MSC were cultured in vitro, and proliferation rate and cell viability were evaluated. Cell suspensions were prepared and surgically administered into the spinal cord. The animals were clinically evaluated and examined by nuclear magnetic resonance. Ten days after the surgical procedure and MSC transplantation, we observed a progressive recovery of the panniculus reflex and diminished superficial and deep pain response, although there were still low proprioceptive reflexes in addition to a hyperreflex in the ataxic hind limb movement responses. Each dog demonstrated an improvement in these gains over time. Conscious reflex recovery occurred simultaneously with moderate improvement in intestine and urinary bladder functions in two of the four dogs. By the 18th month of clinical monitoring, we observed a remarkable clinical amelioration accompanied by improved movement, in three of the four dogs. However, no clinical gain was associated with alterations in magnetic resonance imaging. Our results indicate that MSC are potential candidates for the stem cell therapy following spinal cord injury.

Effect of noxious stimulation factor on γ-aminobutyric acid distribution in dog spinal cord during propofol anesthesia

Objective To evaluate the effect of the noxious stimulation factor on γ-aminobutyric acid (GABA) distribution in dog spinal cord during propofol anesthesia.Methods Sixteen healthy mongrel dogs of both sexes,aged 12-18 months,weighing 10-12 kg,were randomly divided into 2 groups (n =8 each):noxious stimulation group (S group) and control group (C group).Anesthesia was induced with propofol 7 mg/kg.The animals were mechanically ventilated after tracheal intubation.Right femoral artery was cannulated for mean arterial pressure (MAP) and pulse rate monitoring.Anesthesia was maintained with propofol infusion at a constant rate of 70 mg· kg-1 · h-1.5 ％ formalin 300 μl was subcutaneously injected into the central region of tails in group S,while the equal volume of normal saline was injected instead of formalin in group C.MAP and pulse rate were recorded before injection of formalin or normal saline (T1) and after injection of formalin or normal saline (T2).The dogs were scarified by decapitation at 50 min of continuous propofol infusion and cervical 2-3 segments of the spinal cord were removed for determination of GABA level in different regions of the spinal cord (frontal horn,posterior horn,intermediate zone,frontal funiculus,posterior funiculus and lateral funiculus) by HPLC.Results MAP and pulse rate were significantly higher at T2 than at T1 in S group (P ＜ 0.05).There were no significant differences in GABA level among the different regions of the spinal cord in C group (P ＞ 0.05).Compared with C group,GABA level in the frontal horn and posterior horn was significantly increased (P ＜ 0.05),and no significant change was found in the other regions of the spinal cord in S group (P ＞ 0.05).Conclusion The noxious stimulation factor can induce an increase in GABA level in the frontal horn and posterior horn of dog spinal cord during propofol anesthesia. Key words: Stimulation, chemical ; Propofole ; Spinal cord ; Receptors, GABA

Evaluation of normal appearing spinal cord by diffusion tensor imaging, fiber tracking, fractional anisotropy, and apparent diffusion coefficient measurement in 13 dogs.

BackgroundFunctional magnetic resonance (fMR) imaging offers plenty of new opportunities in the diagnosis of central nervous system diseases. Diffusion tensor imaging (DTI) is a technique sensitive to the random motion of water providing information about tissue architecture. We applied DTI to normal appearing spinal cords of 13 dogs of different breeds and body weights in a 3.0 T magnetic resonance (MR) scanner. The aim was to study fiber tracking (FT) patterns by tractography and the variations of the fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) observed in the spinal cords of dogs with different sizes and at different locations (cervical and thoracolumbar). For that reason we added a DTI sequence to the standard clinical MR protocol. The values of FA and ADC were calculated by means of three regions of interest defined on the cervical or the thoracolumbar spinal cord (ROI 1, 2, and 3).ResultsThe shape of the spinal cord fiber tracts was well illustrated following tractography and the exiting nerve roots could be differentiated from the spinal cord fiber tracts. Routine MR scanning times were extended for 8 to 12 min, depending on the size of the field of view (FOV), the slice thickness, and the size of the interslice gaps. In small breed dogs (< 15 kg body weight) the fibers could be tracked over a length of approximately 10 vertebral bodies with scanning times of about 8 min, whereas in large breed dogs (> 25 kg body weight) the traceable fiber length was about 5 vertebral bodies which took 10 to 12 min scanning time. FA and ADC values showed mean values of 0.447 (FA), and 0.560 × 10-3 mm2/s (ADC), respectively without any differences detected with regard to different dog sizes and spinal cord 45 segments examined.ConclusionFT is suitable for the graphical depiction of the canine spinal cord and the exiting nerve roots. The FA and ADC values offer an objective measure for evaluation of the spinal cord fiber integrity in dogs.

Redução da expressão astrocitária de proteína glial fibrilar ácida em cães tratados com dexametasona

A proteína glial fibrilar ácida (GFAP) constitui o principal marcador dos astrócitos, as células gliais mais numerosas do tecido nervoso e que exibem receptores a diversos hormônios esteroidais, os quais exercem aparente influência sobre a expressão gênica das mesmas. O objetivo do presente estudo foi o de avaliar se a administração de dexametasona (DX) em protocolos terapêuticos para cães seria capaz de afetar a expressão astrocitária dessa proteína. Para tal, amostras da ponte e da medula espinhal torácica de cães, tratados (n=6) ou não (n=6) com DX, foram submetidas à marcação imuno-histoquímica para a GFAP e a reatividade astrocitária foi determinada por colorimetria em um sistema computacional de análise de imagens. Diferença estatisticamente significativa foi constatada para as médias das áreas marcadas para GFAP na ponte de cães tratados e não-tratados com DX, assim como na medula espinhal torácica dos que haviam recebido previamente o corticoide ou não, com clara tendência, induzida pela droga, de redução da expressão astrocitária da proteína. Além disso, a expressão de GFAP na medula espinhal foi maior que na ponte, independentemente do emprego de DX ou não.