The function, composition and analysis of cerebrospinal fluid in companion animals: Part II – Analysis

Prevalence of neurological diseases associated with cervical pain and/or signs of cervical myelopathy in French bulldogs: a retrospective analysis of 105 cases

Introduction

French bulldogs can be affected by several neurological diseases, with myelopathies representing the most frequent cause of neurological signs. Studies focusing on the epidemiology of cervical diseases in this breed are lacking. This study aims to describe the prevalence of neurological pathologies responsible for cervical pain and/or signs of cervical myelopathy, assuming that intervertebral disc herniation represents the most common disease; a second aim was to evaluate how often different pathologies coexist in this spinal region in French bulldogs.

Materials and methods

A retrospective analysis of medical records from the database of a single referral center (AniCura I Portoni Rossi Veterinary Hospital-Zola Predosa, Bologna, Italy) was performed, including French bulldogs presented for neck pain and/or neurological deficits consistent with cervical myelopathy. Clinical and imaging data were reviewed and used as inclusion criteria. Based on the number of MRI-diagnosed diseases, the eligible dogs were divided into three groups.

Results

One hundred five French bulldogs met the inclusion criteria. The most commonly diagnosed condition was an intervertebral disc herniation (66.9%), followed by C2 idiopathic hypertrophic ganglioneuritis (15.1%), cervical syringomyelia (11.5%), congenital osseous malformations (1.4%), spinal arachnoid diverticula (1.4%), neoplasms (1.4%), steroid-responsive meningitis-arteritis (0.7%), traumatic vertebral fractures (0.7%), and other (0.7%). For the vast majority of dogs (75/105) a single pathology was diagnosed, with intervertebral disc herniations accounting for 86.7% of cases, involving C3-C4 IVD most commonly. In the remaining 30 dogs, two or three different and concurrent diseases were detected. Among these 30 dogs, intervertebral disc herniations still remained the most diagnosed condition, in combination with C2 idiopathic hypertrophic ganglioneuritis and syringomyelia in 19 and seven cases, respectively.

Conclusion

The results of this study highlight that different pathologies can affect the cervical spinal cord in French bulldogs, with intervertebral disc herniations representing the most frequent condition, as previously described in the veterinary literature. In almost a third of cases, different pathologies can coexist at the cervical level. However, for cases in which different pathologies are present at the same time, it is not always possible to clearly establish their clinical significance.

Canine Cerebrospinal Fluid Analysis Using Two New Automated Techniques: The Sysmex XN-V Body Fluid Mode and an Artificial-Intelligence-Based Algorithm

Cerebrospinal fluid analysis is an important diagnostic test when assessing a neurological canine patient. For this analysis, the total nucleated cell count and differential cell counts are routinely taken, but both involve time-consuming manual methods. To investigate faster automated methods, in this study, the Sysmex XN-V body fluid mode and the deep-learning-based algorithm generated by the Olympus VS200 slide scanner were compared with the manual methods in 161 canine cerebrospinal fluid samples for the total nucleated cell count and in 65 samples with pleocytosis for the differential counts. Following incorrect gating by the Sysmex body fluid mode, all samples were reanalyzed with manually set gates. The Sysmex body fluid mode then showed a mean bias of 15.19 cells/μL for the total nucleated cell count and mean biases of 4.95% and -4.95% for the two-part differential cell count, while the deep-learning-based algorithm showed mean biases of -7.25%, -0.03% and 7.27% for the lymphocytes, neutrophils and monocytoid cells, respectively. Based on our findings, we propose that the automated Sysmex body fluid mode be used to measure the total nucleated cell count in canine cerebrospinal fluid samples after making adjustments to the predefined settings from the manufacturer. However, the two-part differential count of the Sysmex body fluid mode and the deep-learning-based algorithm require some optimization.

Evaluation of an ultrasound-guided freeze-core biopsy system for canine and feline brain tumors

Objective

To determine if a single brain biopsy utilizing a freeze-core needle harvest system Cassi II under ultrasound guidance provides a diagnostic sample; to evaluate the technique's efficacy in procuring diagnostic samples in comparison with "open" surgical biopsies; and to describe intraoperative complications associated with the technique.

Study design

Experimental clinical study.

Animals

Seventeen dogs and four cats with magnetic resonance imaging (MRI) diagnoses of readily surgically accessible intracranial masses.

Methods

Immediately prior to surgical biopsy (SB), freeze-core biopsy (FCB) sample was obtained from each patient under ultrasound guidance.

Results

Histopathology results from single FCB samples were found to be in 100% agreement with the SB samples. Freezing artifact was minimal and did not interfere with histopathologic interpretation. There were no intraoperative complications specifically attributable to the use of the FCB system.

Conclusion

Based on the results of this small experimental study, the FCB system is expected to safely yield diagnostic quality intracranial masses biopsy specimens.

Clinical significance

This system has the potential of obtaining diagnostic biopsies of more deeply seated brain lesions (i.e., intra-axial tumors considered inaccessible or with large risks/difficulties by standard surgical means) which would provide a definitive diagnosis to guide appropriate therapy.

Comparison of D-dimer concentration and thromboelastography for diagnosis of cerebrovascular accidents in dogs: A retrospective study

BACKGROUND

Cerebrovascular accidents (CVAs) in dogs are diagnosed using magnetic resonance imaging (MRI). This modality is sometimes unavailable, and CVAs can resemble other lesions on MRI. D-dimer concentration and thromboelastography (TEG) are utilized in human medicine in addition to diagnostic imaging to support diagnosis of CVAs, but their use in veterinary patients has not been assessed.

OBJECTIVE

Assess utility of blood D-dimer concentration and TEG in supporting the imaging diagnosis of CVAs in dogs.

ANIMALS

Sixty-eight client-owned dogs with neurologic signs that had brain MRI and D-dimer concentration or TEG performed.

METHODS

Multicenter, retrospective study. The incidence of abnormal D-dimer concentration or TEG was compared between patients with MRI evidence of CVA and a control population. Analysis methods included Fisher's exact test or Chi-squared test for association and comparison of independent proportions.

RESULTS

Neither D-dimer concentration nor TEG was significantly associated with a CVA (P = .38 and .2, respectively). D-dimer testing was performed in a low-risk population and showed low sensitivity (30.8%; 95% confidence interval [CI], 10%-61%) and high specificity (86.4%; 95% CI, 64%-96%) for CVA diagnosis. Thromboelastography was performed in a high-risk population and showed moderate sensitivity (64.3%; 95% CI, 44%-81%) and specificity (66.7%; 95% CI, 24%-94%) for CVA diagnosis. Abnormal D-dimer concentration or TEG were not helpful in differentiating hemorrhagic from ischemic stroke (P = .43 and .41, respectively).

CONCLUSIONS

Although blood D-dimer concentration or TEG alone are not diagnostic of CVAs in dogs, a positive D-dimer result supports additional testing for CVA.

Inflammatory mediators drive neuroinflammation in autism spectrum disorder and cerebral palsy

Inflammation conditions are associated with autism spectrum disorder (ASD) and cerebral palsy (CP), primarily observed in the peripheral immune system. However, the extent of neuro-inflammation and neuro-immune dysregulation remains poorly studied. In this study, we analyzed the composition of cerebrospinal fluid (CSF) to uncover the inflammatory mediators driving the neuro-immune system in ASD and CP patients. Our findings revealed that ASD patients had elevated levels of four inflammatory cytokines (TNF-α, IL-4, IL-21, and BAFF) compared to controls, while CP patients exhibited increased levels of eight inflammatory cytokines (IFN-γ, GM-CSF, TNF-α, IL-2, IL-4, IL-6, IL-17A and IL-12), one anti-inflammatory cytokine (IL-10), and five growth factors (GFs) (NGF-β, EGF, GDF-15, G-CSF and BMP-9) compared to both controls and ASD patients. Additionally, intrathecal infusion of autologous bone marrow mononuclear cells (BMMNCs) led to a slight decrease in TGF-β and GDF-15 levels in the CSF of ASD and CP patients, respectively. Our study provides new insights into the molecular composition of CSF in ASD and CP patients, with the potential to develop more effective diagnosis methods and improved treatment for these diseases.Clinical trial registration CSF samples used in this study are from clinical trials NCT03225651, NCT05307536, NCT02569775, NCT03123562, NCT02574923, NCT05472428 and previous reports [7, 9, 17-19].

Retrospective evaluation of prognosis and survival with various immunosuppressants in 82 dogs diagnosed with meningoencephalitis of unknown etiology (2010-2021)

BACKGROUND

Meningoencephalomyelitis of unknown etiology (MUE) is a comprehensive term for non-infectious inflammatory brain diseases of the central nervous system (CNS) caused by abnormal autoimmune responses. This study aims to compare the differences in survival and clinical response of MUE according to the adjuvant immunosuppressant use. Medical records of 82 dogs diagnosed with MUE were reviewed retrospectively.

RESULTS

The overall survival time was 769 days (range 14-2687 days). The median survival time for each adjunctive was: leflunomide 1035 days (range 126-2163 days), mycophenolate mofetil 865 days (range 39-2191 days), cyclosporin 441 days (range 11-2176 days), cytosine arabinoside 754 days (range 6-1898 days) and a combination of mycophenolate mofetil and cytosine arabinoside 132 days (range 23-1227 days). There was no significant difference in the incidence rate of adverse events according to the immunosuppressants, but moderate to severe anemia was confirmed in 3 patients (18.7%) in the leflunomide group.

CONCLUSIONS

The survival time and response rate of MUE dogs differed depending on which adjunctive immunosuppressants were used. Leflunomide showed a long survival time and a relatively good response rate in dogs with MUE. However, a large-scale further study with standardized doses of immunosuppressants and supportive treatment and constant monitoring interval is needed.

Evaluation of a Manual Cytocentrifuge versus the Standard Automated Cytocentrifuge in the Analysis of Canine Cerebrospinal Fluid: A Case Series of 55 Dogs

Cytospins are important for evaluating fluids with very low cellularity such as cerebrospinal fluid (CSF). The aim of this study was to compare the CSF cytospin preparations obtained from automated and manual cytocentrifugation methods. A prospective case series was performed to analyze canine CSF samples using both centrifugation methods. The cytospins were processed within 30-60 min and prepared simultaneously in a conventional automated cytocentrifuge and in an in-house manual cytocentrifuge, using a fixed volume of CSF fluid. The cellularity, differential cell count and the proportion of cell artifacts (pseudopods and vacuolization) were blindly assessed in the cytospin preparations obtained using the two methods. The agreement and correlation between both methods were analyzed. There were 55 dogs enrolled (48 prospectively and 7 retrospectively) in the study. 38 dogs had normal total nucleated cell counts, while 17 had pleocytosis. Automated and manual cytocentrifugation had similar cell yields, and no significant differences in differential cell counts or the presence of artifacts existed between both methods. In cases with pleocytosis, the cytologic diagnosis obtained using each method was similar. Manual cytocentrifugation of CSF is a reliable and economic method designed for routine clinical practice. Its use reduces the specimen deterioration related to processing and analysis delays when samples are transported to external laboratories for evaluation.

Complications associated with cerebrospinal fluid collection in dogs

BACKGROUND

This study aimed to identify complications associated with cerebrospinal fluid (CSF) collection in dogs.

METHODS

This was a prospective, observational multicentre study using data collected from 102 dogs undergoing CSF collection for the investigation of neurological disease. CSF was collected from the cerebellomedullary cistern (CMC), lumbar subarachnoid space (LSAS) or both sites. Pre-, intra- and postprocedural data were collected. Descriptive statistics were performed to outline complications associated with CSF collection.

RESULTS

CSF sampling was attempted on 108 occasions, and CSF was acquired on 100 occasions (92.6%). Collection from the CMC was more likely to be successful than that from the LSAS. No dogs exhibited neurologic deterioration following CSF collection. There was no significant difference between pre- and post-CSF collection short-form Glasgow composite measure pain scores in ambulatory dogs (p = 0.13).

LIMITATIONS

The scarcity of complications limited the ability to quantify the incidence of some potential complications reported elsewhere.

CONCLUSIONS

Our results may be used to inform clinicians and owners that CSF sampling is associated with a low frequency of complications when performed by trained personnel.

Very-Low-Frequency Spike-Wave Complex Partial Motor Seizure Mimicking Canine Idiopathic Head Tremor Syndrome in a Dog

Canine idiopathic head tremor syndrome (CIHTS) represents a benign condition characterized by episodic, uncontrolled movement of the head. Even though the condition might be an expression of a partial motor epilepsy, to date, there is a limited number of studies describing the electroencephalographic features. In this report, we describe the case of a dog diagnosed with partial motor epilepsy resembling CIHTS symptomatology, a new slow spike-wave complex pattern similar to that of Lennox-Gastaut syndrome in humans identified on electroencephalographic examination. We also studied the efficacy of phenobarbitone therapy over a period of two years.

Investigation of the presence of specific neural antibodies in dogs with epilepsy or dyskinesia using murine and human assays

BACKGROUND

Autoimmune mechanisms represent a novel category for causes of seizures and epilepsies in humans, and LGI1-antibody associated limbic encephalitis occurs in cats.

HYPOTHESIS/OBJECTIVES

To investigate the presence of neural antibodies in dogs with epilepsy or dyskinesia of unknown cause using human and murine assays modified for use in dogs.

ANIMALS

Fifty-eight dogs with epilepsy of unknown cause or suspected dyskinesia and 57 control dogs.

METHODS

Serum and CSF samples were collected prospectively as part of the diagnostic work-up. Clinical data including onset and seizure/episode type were retrieved from the medical records. Screening for neural antibodies was done with cell-based assays transfected with human genes for typical autoimmune encephalitis antigens and tissue-based immunofluorescence assays on mouse hippocampus slices in serum and CSF samples from affected dogs and controls. The commercial human und murine assays were modified with canine-specific secondary antibody. Positive controls were from human samples.

RESULTS

The commercial assays used in this study did not provide unequivocal evidence for presence of neural antibodies in dogs including one dog with histopathologically proven limbic encephalitis. Low titer IgLON5 antibodies were present in serum from one dog from the epilepsy/dyskinesia group and in one dog from the control group.

CONCLUSION AND CLINICAL IMPORTANCE

Specific neural antibodies were not detected using mouse and human target antigens in dogs with epilepsy and dyskinesia of unknown origin. These findings emphasize the need for canine-specific assays and the importance of control groups.

Towards optimised extracellular vesicle proteomics from cerebrospinal fluid

The proteomic profile of extracellular vesicles (EVs) from cerebrospinal fluid (CSF) can reveal novel biomarkers for diseases of the brain. Here, we validate an ultrafiltration combined with size-exclusion chromatography (UF-SEC) method for isolation of EVs from canine CSF and probe the effect of starting volume on the EV proteomics profile. First, we performed a literature review of CSF EV articles to define the current state of art, discovering a need for basic characterisation of CSF EVs. Secondly, we isolated EVs from CSF by UF-SEC and characterised the SEC fractions by protein amount, particle count, transmission electron microscopy, and immunoblotting. Data are presented as mean ± standard deviation. Using proteomics, SEC fractions 3-5 were compared and enrichment of EV markers in fraction 3 was detected, whereas fractions 4-5 contained more apolipoproteins. Lastly, we compared starting volumes of pooled CSF (6 ml, 3 ml, 1 ml, and 0.5 ml) to evaluate the effect on the proteomic profile. Even with a 0.5 ml starting volume, 743 ± 77 or 345 ± 88 proteins were identified depending on whether 'matches between runs' was active in MaxQuant. The results confirm that UF-SEC effectively isolates CSF EVs and that EV proteomic analysis can be performed from 0.5 ml of canine CSF.

MicroRNA profiling of cerebrospinal fluid from dogs with steroid responsive meningitis-arteritis and meningoencephalitis of unknown origin

Introduction

Non-infectious inflammatory diseases of the central nervous system in dogs, such as steroid responsive meningitis-arteritis (SRMA) and meningoencephalitis of unknown origin (MUO), represent a common clinical challenge that needs extensive and multimodal work-up to reach a presumptive diagnosis. Both diseases are presumably caused by dysregulations of the immune system, but further research is needed in order to understand the molecular mechanisms behind each disease and to optimize treatment.

Methods

By next-generation sequencing and subsequent quantitative real-time PCR (qPCR) verification, we designed a prospective case-control pilot study to analyze the small RNA profiles of cerebrospinal fluid from dogs suffering from MUO (N = 5), dogs suffering from SRMA (N = 8), and healthy dogs (N = 5) presented for elective euthanasia used as the Control group.

Results

Our results showed an overall enrichment in Y-RNA fragments across all samples, followed by microRNAs (miRNAs) and ribosomal RNAs as the major findings. Additional traces of short RNA reads mapped to long non-coding RNAs and protein-coding genes were also found. From the detected canine miRNAs, miR-21, miR-486, miR-148a, miR-99a, miR-191 and miR-92a were among the most abundant. Dogs with SRMA showed higher differences in miRNA abundance than dogs with MUO when compared to healthy dogs, and miR-142-3p was consistently detected as differentially upregulated in both diseases, although at a low concentration. Moreover, miR-405-5p and miR-503-5p showed different profiles between SRMA and MUO dogs. Subsequent qPCR analyses confirmed miR-142-5p, miR-191-5p and miR-92a-3p as significantly upregulated miRNAs in dogs with SRMA and/or MUO.

Discussion

Cerebrospinal fluid is a challenging biological material to use for profiling miRNAs due to the low content of circulating RNAs. Despite this, we could confirm several miRNAs being differentially abundant when comparing healthy dogs and dogs with MUO and SRMA, respectively. The results of this study indicate a potential role of miRNAs in the underlying molecular mechanisms of these diseases and establish the basis for further studies.

The Reibergram for immunoglobulin A in dogs: Evaluation of intrathecal IgA synthesis using a quotient graph in dogs with neurological diseases

BACKGROUND

Increased cerebrospinal fluid (CSF) protein concentration is a common finding in neurological diseases of dogs. Distinguishing between intrathecally-produced proteins and proteins that have passed the blood-CSF barrier because of barrier disruption facilitates diagnosis. Albumin is a microprotein mainly produced extrathecally that can be used as a reference marker for blood-CSF barrier dysfunction.

OBJECTIVES

Develop a quotient graph based on the CSF/serum quotient of albumin and immunoglobulin A (IgA; Reibergram) to visualize intrathecal IgA synthesis and blood-CSF barrier dysfunction.

ANIMALS AND METHODS

Retrospective single-center cohort study. A hyperbolic function was developed using data from 6 healthy Beagles and 38 dogs with neurological diseases in which an isolated blood-CSF barrier dysfunction was expected. The function was validated using data from 10 dogs with expected intrathecal IgA synthesis and was visualized as a quotient graph. Finally, the graph was used to evaluate data of 118 dogs with various neurological diseases.

RESULTS

Within the Reibergram, the function QLim IgA = 0.13 QAlb 2 + 11.9 · 10 - 6 - 1.01 · 10 - 3 describes the upper values of physiological IgA quotients. It detects diseases with expected intrathecal IgA synthesis with higher sensitivity (85%) and specificity (89%) than the IgA index. The upper value of the physiological albumin quotient is 2.22 and detects diseases with expected blood-CSF barrier dysfunction (sensitivity: 81%; specificity: 88%).

CONCLUSION AND CLINICAL IMPORTANCE

The canine Reibergram can detect blood-CSF barrier dysfunction and intrathecal IgA synthesis in the majority of cases. The graphical visualization simplifies data evaluation and makes it a feasible tool in routine CSF diagnostic testing.

Dynamics of cerebrospinal fluid in correction of degenerative lumbosacral stenozis during the postoperative period in dogs

Dynamics of cerebrospinal fl parameters in postoperative period during correction of degenerative lumbosacral stenosis in dogs is an important diagnostic aspect that allows monitoring changes in the state of animals after surgery. An accurate analysis of cerebrospinal fl id provides a wide range of information about the patients neurological health. The assessment should consist of macroscopic, quantitative and microscopic analyses. Сell count is the most important and potentially sensitive indicator of disease. The aim of this study was to determine changes in the cerebrospinal fluid during the postoperative period in the correction of degenerative lumbosacral stenosis. In the study, there were 9 dogs of various breeds, aged from 2 to 8 years (experimental group), the indicators of cerebrospinal fluid and peripheral blood of 3 healthy outbred dogs obtained as a result of medical examination at the age of up to 5 years were used as a control. Surgical intervention was carried out according to the B.P. Meij, N. Bergknut, which consists in dorsal access to the L7-S 1 vertebral arches, soft tissue dissection, dissection of the dorsal ligament, formation of channels in the cranial articular processes of S 1, L7. From each animal, three liquorograms were taken for examination three times on days 1-3 after surgery, on days 12-15 and 27-30 after surgery. The study of cerebrospinal fluid was performed within 30 minutes after taking. As a result of the data obtained, it was found that the cellular composition of the liquor of dogs in the postoperative period of correction of lumbosacral stenosis was within the physiological norm, erythrocytes in the cerebrospinal fluid were not detected. The number of nucleated cells in operated dogs was the highest on days 1-3 after surgery. On the 12th-15th day after the operation, cytosis in the experimental and control groups of animals was 1.27 cells/l more. On days 27-30 after surgery, cytosis in dogs in the experimental group was lower by 0.45 cells/l compared to the control. Analysis of cerebrospinal fluid can help in the diagnostic assessment of the condition of animals in the postoperative period. However, it should be borne in mind that results are rarely specific to any particular condition and should be interpreted in the light of clinical and additional diagnostic findings.

Magnetic resonance imaging highlights the meningeal involvement in steroid responsive meningitis-arteritis and suggests the inflammation of the surrounding tissues (70 cases)

Introduction

Steroid-responsive meningitis-arteritis (SRMA) is an immune-mediated disorder of young dogs for which there is no definitive ante-mortem diagnostic test. Magnetic Resonance Imaging (MRI) can be used to explore other differentials and extensive reports about its usefulness in the diagnosis of SRMA are lacking. The aims of this study were to retrospectively investigate the characteristics of MRI studies of the cervical spine of dogs diagnosed with SRMA and to compare the diagnostic capability of MRI obtained with low-field and high-field units.

Materials and methods

This is a double center, retrospective case series. Databases were searched between 2008 and 2021 for dogs with a diagnosis of SRMA. Dogs were included if the following criteria were fulfilled: a diagnosis of cervical SRMA, results of CSF analysis, and MRI of the cervical spine available for re-evaluation.

Results

Seventy cases were selected. MRI abnormalities were found in 69 cases (98.6%). Enhancement of the meninges, nerve roots, synovium of the articular facets and paravertebral muscles was present in 61 (87.1%), 10 (14.3%), 34 (48.6%), and 34 (48.6%) cases, respectively, when considering all MRI. In the low-field MRI, enhancement of these structures was present in 45 (90%), 4 (8%), 21 (42%) and 23 (46%) cases, respectively. In the high-field MRI, enhancement of these structures was present in 16 (80%), 6 (30%), 13 (65%) and 11 (55%) cases, respectively. Fat suppressed T1W images showed meningeal enhancement better than T1W images. When all the MRIs were considered, a significant increase in cell count of the cerebrospinal fluid was found between the three groups based on the meningeal MRI score (p = 0.001). In cases with no meningeal enhancement but enhancement of synovium of the articular facets and/or muscles a significantly lower cerebrospinal fluid cell count was present (p = 0.043), when considering all MRIs.

Conclusions

The most frequent detection on cervical MRI of dogs affected by SRMA is meningeal enhancement, often accompanied by enhancement of the synovium of the articular facets and/or muscular enhancement. Both low-field and high-field MRI have good diagnostic capability but the latter enables a more thorough investigation thanks to specific sequences. MRI is useful as a complementary tool to cerebrospinal fluid analysis.

CLINICAL AND HISTOPATHOLOGICAL FINDINGS OF HEMORRHAGIC ASCENDING AND DESCENDING PROGRESSIVE MYELOMALACIA AFTER LUMBAR TAP IN TWO DOGS: CASE REPORT

Bichon Frise (1) and Boxer (2), both with epileptic seizures, underwent lumbar taps for cerebrospinal fluid collection. After the examination, the first dog became paraplegic, and the second dog did not recover from anesthesia and remained in a coma. Both dogs were euthanatized 12 h after the examination. The dogs were diagnosed with idiopathic epilepsy and fibrillar astrocytoma, respectively, after postmortem examination. They were also diagnosed with hemorrhagic ascending and descending progressive myelomalacia, involving C1-C5 until the L4-S3 spinal segments. Since it was not possible to attribute the development of myelomalacia to the primary diseases observed, the lumbar tap likely caused this severe spinal cord injury. These reports highlight myelomalacia as a possible complication of lumbar taps, even in the presence of intracranial diseases.

Idiopathic generalised tremor syndrome in dogs

BACKGROUND

Idiopathic generalised tremor syndrome (IGTS) causes tremor and often vestibulocerebellar signs. Previous publications on IGTS in dogs are restricted to case reports or lack exclusion of structural causes.

METHODS

Medical records of 75 dogs diagnosed with IGTS that had undergone magnetic resonance imaging (MRI) of the brain were collected retrospectively.

RESULTS

Crossbreeds were affected most commonly (41.3%), followed by West Highland white terriers (14.7%) and cocker spaniels (10.7%). A higher proportion of females were affected than males (68.0%). Median age of the affected dogs was 17 months (range 6-121 months), and median bodyweight was 9.15 kg (range 2.9-26 kg). All dogs presented with tremors and most experienced concomitant neurological signs (93.3%). Seventeen (22.7%) were hyperthermic and 31 (41.3%) had gastrointestinal signs. MRI of the brain was normal in most of the cases, and cerebrospinal fluid analysis frequently revealed mild pleocytosis. All animals were treated with prednisolone, and 39 (51.3%) also received diazepam. Median follow-up time was 13 months (range 0-134 months). The overall outcome was good, although 16 (21.3%) patients were reported to have relapsing clinical signs and 10 (13.2%) patients experienced persistent mild clinical signs.

CONCLUSIONS

IGTS should be suspected in any dog with generalised tremor and vestibulocerebellar signs with younger and smaller dogs more commonly affected.

Case Report: Bordetella bronchiseptica Meningoencephalomyelitis in a Dog

A 15-month-old male neutered Wirehaired Pointer mixed-breed dog presented with fever and cervical pain. Cerebrospinal fluid (CSF) analysis showed neutrophilic pleocytosis with intracellular bacteria, and culture of CSF grew Bordetella bronchiseptica. The patient became non-ambulatory 3 days after CSF collection. He was treated with low-dose prednisone for 3.5 months and doxycycline for 1 year. Recheck CSF analysis 1 month after diagnosis showed reduction of inflammation and 3 months after diagnosis revealed only increased protein. The patient improved neurologically over several months and was weakly ambulatory 5 months and fully ambulatory 7 months after diagnosis. Whole genome sequencing of the bacterial isolate and a live modified intranasal vaccine similar to the one the dog had been vaccinated with 7 weeks before diagnosis was similar but not an exact match. Bacterial meningitis should be considered, and culture of CSF is recommended, in cases of neutrophilic pleocytosis of CSF.

Raman, Infrared and Brillouin Spectroscopies of Biofluids for Medical Diagnostics and for Detection of Biomarkers

This review surveys Infrared, Raman/SERS and Brillouin spectroscopies for medical diagnostics and detection of biomarkers in biofluids, that include urine, blood, saliva and other biofluids. These optical sensing techniques are non-contact, noninvasive and relatively rapid, accurate, label-free and affordable. However, those techniques still have to overcome some challenges to be widely adopted in routine clinical diagnostics. This review summarizes and provides insights on recent advancements in research within the field of vibrational spectroscopy for medical diagnostics and its use in detection of many health conditions such as kidney injury, cancers, cardiovascular and infectious diseases. The six comprehensive tables in the review and four tables in supplementary information summarize a few dozen experimental papers in terms of such analytical parameters as limit of detection, range, diagnostic sensitivity and specificity, and other figures of merits. Critical comparison between SERS and FTIR methods of analysis reveals that on average the reported sensitivity for biomarkers in biofluids for SERS vs FTIR is about 103 to 105 times higher, since LOD SERS are lower than LOD FTIR by about this factor. High sensitivity gives SERS an edge in detection of many biomarkers present in biofluids at low concentration (nM and sub nM), which can be particularly advantageous for example in early diagnostics of cancer or viral infections.HighlightsRaman, Infrared spectroscopies use low volume of biofluidic samples, little sample preparation, fast time of analysis and relatively inexpensive instrumentation.Applications of SERS may be a bit more complicated than applications of FTIR (e.g., limited shelf life for nanoparticles and substrates, etc.), but this can be generously compensated by much higher (by several order of magnitude) sensitivity in comparison to FTIR.High sensitivity makes SERS a noninvasive analytical method of choice for detection, quantification and diagnostics of many health conditions, metabolites, and drugs, particularly in diagnostics of cancer, including diagnostics of its early stages.FTIR, particularly ATR-FTIR can be a method of choice for efficient sensing of many biomarkers, present in urine, blood and other biofluids at sufficiently high concentrations (mM and even a few µM)Brillouin scattering spectroscopy detecting visco-elastic properties of probed liquid medium, may also find application in clinical analysis of some biofluids, such as cerebrospinal fluid and urine.

Performance of the Sysmex XN-V body fluid module for canine cerebrospinal fluid cell count

BACKGROUND

Microscopic cell counts and nucleated cell identification are the "gold standard" for cerebrospinal fluid (CSF) assessments and are labor intensive and subject to operator variability. The use of automated methods could be an alternative to the current manual technique.

OBJECTIVES

We aimed to assess the utility of the Sysmex XN-V body fluid (BF) module analyzer to count and differentiate nucleated cells in canine CSF and evaluate the accuracy and correlation between this and the manual method.

METHODS

We prospectively analyzed 150 CSF samples from dogs using the Sysmex XN-V BF module and compared the results with those obtained using the manual counting method. We also evaluated the linearity, detection limits, and imprecision of the Sysmex XN-V BF module.

RESULTS

The Sysmex XN-V BF module analyzer performance had a sensitivity of 92.59% and specificity of 94.30%. The lower limit of quantification for the total nucleated cell count (TNCC) was 0 cells/μL. A Pearson´s correlation coefficient of 0.945 was found between both methods for TNCC, with 0.997 and 0.940 for samples with TNCC >10 cells/μL and TNCC >5 cells/μL, respectively. The correlation coefficient for the mononuclear and polymorphonuclear differential cell count was -0.031 and -0.019, respectively, and it was 0.576 for the RBC count.

CONCLUSIONS

The Sysmex XN-V BF module provides reliable TNCCs for canine CSF, even for samples with low cell numbers, but manual cytologic evaluation is still needed for differential cell counts.

Diagnostic utility of canine cerebrospinal fluid preserved by 10% buffered formalin

OBJECTIVES

To examine the diagnostic utility of canine cerebrospinal fluid samples collected into tubes containing ethylenediaminetetraacetic acid (EDTA) with and without the addition of 10% buffered formalin analysed within 6 to 20 hours.

MATERIALS AND METHODS

Inclusion criteria were dogs presenting to a referral hospital with neurological signs and having cerebrospinal fluid analysis performed. Samples were submitted to an external laboratory in tubes containing ethylenediaminetetraacetic acid as paired-samples; one with the addition of one drop of 10% buffered formalin and the other without formalin. Cytology report, total nucleated cell counts, and protein concentration were reviewed. Three different categories of cell preservation were defined: diagnostic, non-diagnostic and unclassified. Each sample was included in one of these categories depending on cytological features, and the diagnostic quality between samples was compared. Samples were further divided in two groups depending on protein concentration using 50 mg/dL as cut-off value and the diagnostic quality between samples was compared.

RESULTS

254 samples from 127 dogs were included. 47% of samples without formalin were non-diagnostic, 46% diagnostic and 6% unclassified. In the formalin group, 2% samples were non-diagnostic, 92% diagnostic and 6% unclassified. Samples with formalin preservation were statistically more likely to be diagnostic than samples without formalin preservation. In both protein groups (≥50 and <50 mg/dL) formalin samples were statistically more likely to be diagnostic as well.

CLINICAL SIGNIFICANCE

The addition of one drop of 10% formalin is a simple, widely available method which can help to improve the accuracy of cytological assessment in canine cerebrospinal fluid by preserving cellular morphology when analysis is performed within 6 to 20 hours.

Suspected acquired narcolepsy in 8 dogs

Background

Acquired narcolepsy has rarely been reported in veterinary medicine.

Objective

To describe the presentation, clinicopathological features, diagnostic imaging findings, and management of dogs with suspected‐acquired narcolepsy.

Animals

Eight dogs with clinical features consistent with acquired narcolepsy.

Methods

A call for suspected cases of acquired narcolepsy was made online, followed by a retrospective review of detailed medical records of potential cases. Dogs were included if episodes consistent with cataplexy were present during examination by a board‐certified veterinary neurologist and diagnostic work‐up included magnetic resonance imaging of the brain and analysis of cerebrospinal fluid.

Results

Seven French Bulldogs and 1 Chihuahua (age range, 9‐66 months) were included. Meningoencephalitis of unknown origin was diagnosed in 2 dogs, extracranial foci of inflammation were identified in 2 dogs (aspiration pneumonia, esophagitis, otitis media), and no abnormalities were found on diagnostic investigations in 4 dogs. Prednisolone was used in the management of all dogs, 6 dogs received imipramine, and 2 received cytosine arabinoside. An initial remission of signs was observed in all dogs, but a subsequent relapse of clinical signs was recorded for 4 dogs, of which 3 responded to adjustment or resumption of treatment.

Conclusions and Clinical Importance

The presence of cataplexy episodes should prompt a thorough diagnostic work‐up to exclude the presence of intracranial (and extracranial) pathology. The potential for both remission and relapse of signs in suspected acquired cases is important for clinicians and owners to be aware of.

COMPOSITION OF CEREBROSPINAL FLUID IN CLINICALLY NORMAL GRIZZLY BEARS (URSUS ARCTOS HORRIBILIS)

Five cerebrospinal fluid (CSF) samples were collected from four clinically normal grizzly bears from the Washington State University Bear Research, Education, and Conservation Center. CSF samples were collected from the cerebellomedullary cisternal space. Samples were immediately processed and analyzed for microprotein content, red blood cells, white blood cells (WBCs), and differential cell count. Microprotein concentration (range 4.2-14.6 mg/dl; median, less than 6 mg/dl), total WBC count (range 0-2 cells/µl; median 2 cells/µl), and differential WBCs (predominance mononuclear cells) of the five CSF samples were comparable to previously published CSF analyses from clinically normal felines and canines. Providing documentation of CSF composition for clinically normal grizzly bears is important for neurologic disease diagnosis and treatment.

Biomarkers of non-infectious inflammatory CNS diseases in dogs - Where are we now? Part I: Meningoencephalitis of unknown origin

Meningoencephalitides of Unknown Origin (MUO) comprises a group of non-infectious inflammatory brain conditions, which frequently cause severe neurological disease and death in dogs. Although multiple diagnostic markers have been investigated, a conclusive diagnosis, at present, essentially relies on postmortem histopathology. However, different groups of biomarkers, e.g. acute phase proteins, antibodies, cytokines, and neuro-imaging markers may prove useful in the diagnostic investigation of dogs with MUO. It appears from the current literature that acute phase proteins such as C-reactive protein are often normal in MUO, but may be useful to rule out steroid responsive meningitis-arteritis as well as other systemic inflammatory conditions. In antibody research, anti-glial fibrillary acidic protein (GFAP) may play a role, but further research is needed to establish this as a consistent marker of particularly Pug dog encephalitis. The proposed diagnostic markers often lack specificity to distinguish between the subtypes of MUO, but an increased expression of interferon-γ (IFN-γ) in necrotizing meningoencephalitis (NME) and interleukin-17 (IL-17) in granulomatous meningoencephalitis (GME) in tissue biopsies may indicate their potential as specific markers of NME and GME, respectively, suggesting further investigations of these in serum and CSF. While neuro-imaging is already an important part of the diagnostic work-up in MUO, further promising results have been shown with Positron Emission Tomography (PET) as well as proton resonance spectroscopy (¹H MRS), which may be able to detect areas of necrosis and granulomas, respectively, with relatively high specificity. This review presents different groups of established and potential diagnostic markers of MUO assessing current results and future potential.

Evaluation of the Impact of Using a Simulator for Teaching Veterinary Students Cerebrospinal Fluid Collection: A Mixed-Methods Study

The collection of cerebrospinal fluid (CSF) plays a pivotal role in the diagnosis of central nervous system diseases. Prior training in this invasive procedure is essential to minimize the risk of harming animals. Because of this risk, stress and anxiety can influence the learning process. Simulators can be used to teach and learn invasive procedures. The aim of this mixed-methods study was to validate a CSF collection simulator and investigate students' perceptions of the simulator as an educational tool. The quantitative approach validated the simulator for face and content validity, and students provided a general evaluation of the simulator using surveys. The simulator's construct validity was measured by means of a global rating scale. Students' perceptions were investigated qualitatively using semi-structured interviews. Experts (n = 13) confirmed the simulator's face and content validity. Students (n = 16) evaluated the simulator as supportive of their learning. Results for construct validity demonstrated higher global rating scores from experts than from students. The scores for procedural performance and procedural knowledge and flow showed significant differences (p ≤ .05). Analysis of interviews with students (n = 10) revealed four main themes: emotions, learning process, evaluation of the model, and CSF collection procedure. In conclusion, this study validated the use of the CSF simulator as an educational tool that can help students overcome some of their anxiety in relation to performing an invasive procedure.

MRI of CNS lymphoma with choroid plexus involvement in five dogs and one cat

OBJECTIVES

To describe the clinical features, magnetic resonance imaging (MRI) findings, and outcome of dogs and cats with central nervous system (CNS) lymphoma that involved the choroid plexus.

MATERIALS AND METHODS

A bi-institutional retrospective study of MRI of dogs and cats with CNS lymphoma, in which the choroid plexus was affected on MRI. Signalment, clinical, MRI, clinicopathologic and histopathologic findings were recorded and evaluated.

RESULTS

CNS lymphoma with choroid plexus involvement on the MRI was identified in five dogs and one cat. MRI revealed diffuse enlargement and multifocal nodularity in the choroid plexus in most cases, with the fourth ventricle the most common site affected. Five of the cases had signs of extraneural involvement (including the cat), while the sixth case was not staged. Four of five CSF samples analysed provided a diagnosis of lymphoma.

CLINICAL SIGNIFICANCE

We report MRI findings of CNS lymphoma involving the choroid plexus. These results show the importance of recognising novel imaging patterns and the potential utility of CSF collection in diagnosing CNS lymphoma involving the choroid plexus ante mortem.

Acute idiopathic polyradiculoneuritis with secondary arterial hypertension in a 5-year-old male Siberian Husky

Acute canine idiopathic polyradiculoneuritis (ACIP) is one of the most common generalised neuromuscular diseases affecting dogs. In this report, we describe a 5-year-old, 25-kg, male, intact, Siberian Husky dog with ACIP with secondary induced arterial hypertension {systolic blood pressure [mean (m) ± standard deviation (sd)], 214 ± 19 mmHg; mean blood pressure (m ± sd), 164 ± 6.36 mmHg; and diastolic blood pressure (m ± sd), 137 ± 0.7 mmHg} and sinus tachycardia. Heart rate variability analysis indicated decreased vagal activity (low root-mean-square values of successive RR interval differences and percentages of the RR intervals differing by more than 50 ms in the entire recording) and predominance of sympathetic activity. Arterial hypertension was treated with amlodipine but remained greater than the upper limit for 51 days until the dog recovered ambulation. This is the first case report of ACIP and secondary arterial hypertension in a dog. Routine blood pressure measurements should be included in the monitoring of patients with ACIP if arterial hypertension might interfere with patient prognosis.

Role of Leishmania infantum in Meningoencephalitis of Unknown Origin in Dogs from a Canine Leishmaniosis Endemic Area

The main hypothesis for the aetiology of meningoencephalitis of unknown origin (MUO) in dogs is an autoimmune or genetic cause that is associated with a triggering event (environmental factors/infectious agents). The aim of this ambispective cohort study was to test for Leishmania infantum infection in the blood and cerebrospinal fluid (CSF) of dogs with MUO in an endemic area of canine leishmaniosis. Dogs with MUO were selected amongst all dogs undergoing blood anti-L. infantum antibody testing (control group). The blood plasma or serum samples from all dogs were analysed for anti- L. infantum antibodies by a quantitative indirect fluorescent assay (IFAT). In dogs with MUO, CSF samples were obtained for analysed by PCR detection of L. infantum DNA. Forty-four percent and 22% of the dogs in the MUO group featured magnetic resonance imaging (MRI) findings and CSF cytology respectively, consistent with L. infantum infection. IFAT, PCR, and histological findings were negative for L. infantum. A significant difference in L. infantum infection prevalence was found between the control and MUO group (p = 0.0022). While it seems unlikely that L. infantum plays a role in the aetiology of MUO, in endemic areas, this pathogen should be included in the differential diagnosis of this neurological disorder.

Cerebrospinal fluid analysis in dogs: Main patterns and prevalence of albuminocytological dissociation

BACKGROUND

Albuminocytological dissociation (ACD) of the cerebrospinal fluid (CSF) is defined as an increased total protein concentration with normal total nucleated cell count. It is suspected to occur in diseases that alter the blood-brain barrier, increase the production of protein or obstruct the flow of CSF. The purposes of this study were to review the CSF analysis results of a large cohort of dogs with neurological conditions, to analyse the total prevalence of ACD and to describe which diseases have a higher prevalence of ACD.

STUDY DESIGN AND METHODS

Medical records were retrospectively searched for dogs whom CSF was sampled from 2012-2019. Data collected included signalment, body weight, site of collection of the CSF, CSF analysis results, and final diagnosis.

RESULTS

A total of 497 dogs met the inclusion criteria. ACD was identified in 16.5% (82/497) of dogs. The diseases with higher proportion of ACD were cranial nerve neuropathy (6/10; 60.0%), brain tumour (10/24; 41.7%), idiopathic vestibular disease (7/17; 41.2%) and brain vascular disease (4/13; 30.8%).

CLINICAL SIGNIFICANCE

This study describes the CSF patterns of the most common neurological conditions in dogs, also characterizing, for the first time in dogs, the prevalence and causes of ACD, which was identified in 16.5% of the samples. The diseases with highest proportions of ACD were cranial nerve neuropathy, brain tumour, idiopathic vestibular disease and brain vascular disease.

Low-Field Magnetic Resonance Imaging Findings in 18 Dogs With Presumed Optic Neuritis

Canine optic neuritis has been attributed to a focal or disseminated form of granulomatous meningoencephalitis (GME) amongst other etiologies. Magnetic resonance imaging (MRI) has been proven to help differentiate the structures within the optic nerve sheath and therefore could aid the diagnosis of optic neuritis in dogs. The objectives of this study were to describe and compare the MRI abnormalities affecting the optic nerve sheath complex and optic chiasm in dogs with clinically suspected optic neuritis as a component of meningoencephalitis of unknown etiology (MUE) or as an isolated form (I-ON). Retrospective evaluation of patient details, clinical signs, cerebrospinal fluid (CSF) analysis, and MRI findings of dogs with clinically suspected optic neuritis between January 2011 and May 2018 was performed. Eighteen dogs met the inclusion criteria. MRI findings included contrast enhancement of both optic nerves (11/18) and optic chiasm (6/18), changes within the CSF volume surrounding the optic nerve (10/18), changes to the optic disc (10/18), changes of size or signal affecting the optic chiasm (10/18), changes in the Short TI inversion recovery (STIR) signal of the optic nerve (7/15), retrobulbar changes (3/18), and concurrent brain lesions (13/18). A variety of subtle MRI features may indicate optic nerve involvement and low-field MRI is a sensitive method to detect changes within the optic nerve sheath complex in dogs with optic neuritis as an isolated form (I-ON) or as an extension of MUE.

Stability of canine and feline cerebrospinal fluid samples regarding total cell count and cell populations stored in "TransFix®/EDTA CSF sample storage tubes"

Background

Because of fast leucocyte degeneration in cerebrospinal fluid (CSF) laboratory examinations of CSF samples should be performed approximately within 30 min after withdrawal. This study examines the storage of canine and feline CSF samples in “TransFix®/EDTA CSF Sample Storage Tubes” (Cytomark, Buckingham, UK) for preventing leucocytes from degeneration, so that routine and flow cytometry examinations are feasible up to 3 days after sampling.

Results

After storage in TransFix® tubes, leukocytes could not be adequately stained with Türk’s solution and differentiating between erythrocytes and leukocytes was cumbersome. In addition, the cell morphology could not be sufficiently assessed on cytospin preparations because of shrunken leukocytes and indistinct cell nuclei. In contrast, by flow cytometry, a significantly higher cell count was measured over the entire study period in the samples stored in TransFix® tubes compared to the untreated samples. The antibodies (AB) against CD3, CD4 and CD21, against CD11b and against CD45 showed a good binding strength and thus enabled a good differentiation of cell populations. However, after storage in the TransFix® tubes, monocytes were no longer detectable using an AB against CD14.

Conclusion

Based on these results, “TransFix®/EDTA CSF Sample Storage Tubes” can be used for extended storage prior to flow cytometric analysis of lymphocytes and granulocytes in CSF samples but not for detecting monocytes. However, standard examinations, such as microscopic cell counting and morphological cell assessment should be performed on fresh CSF samples.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-020-02698-5.

Survival time and relapse in dogs with meningoencephalomyelitis of unknown origin treated with prednisolone and ciclosporin: a retrospective study

OBJECTIVE

To analyse outcome in dogs with a presumptive diagnosis of meningoencephalomyelitis of unknown origin (MUO) treated with prednisolone and ciclosporin and to assess the effect of a number of patient variables on survival time and rate of relapse.

DESIGN

Retrospective case series.

METHODS

Medical records of 40 client-owned dogs with a diagnosis of MUO treated with prednisolone and ciclosporin at one institution between June 2010 and January 2018 were reviewed retrospectively to assess survival times and prognostic indicators for death and/or relapse. The minimum follow-up time was 11 months post-diagnosis.

RESULTS

Median survival was 1345 days (95% confidence interval: 487-∞). No associations with hazard of death or relapse were detected for the presence of multifocal magnetic resonance imaging (MRI) abnormalities, caudal fossa location of MRI abnormalities, value of cerebrospinal fluid total nucleated cell count or total protein at time of diagnosis, or suspected elevation in intracranial pressure at time of diagnosis.

CONCLUSION

Protracted survival time may be achieved with a treatment combination of prednisolone and ciclosporin. Suspected elevation in intracranial pressure at the time of diagnosis did not affect long-term outcome in this cohort.

Comparison of creatine kinase in cerebrospinal fluid collected from the cerebellomedullary and lumbar cisterna in 10 dogs with neurologic disease

BACKGROUND

Analysis of cerebrospinal fluid CK (CSF-CK) might be useful as a prognostic indicator in dogs with neurologic disease. Previous studies have mostly analyzed CSF-CK collected from the cerebellomedullary (CM) cisterna, but CSF collection sites could affect its levels.

OBJECTIVES

This is a pilot study aimed to evaluate differences in CSF-CK concentrations when collected from the CM or lumbar cisterna in dogs presenting with neurologic disease.

METHODS

Ten dogs presenting for neurologic disease underwent magnetic resonance imaging and CSF collection from both the CM and lumbar cisterna. Cerebrospinal fluid CK was analyzed within 30 minutes.

RESULTS

Ten dogs were prospectively recruited. Overall, there was no statistically significant difference between CSF-CK collected from the CM or lumbar cisterna (P = .31). When evaluated by neurolocalization, CSF-CK was different between sites in dogs with thoracolumbar myelopathy (P = .024), but not in dogs with intracranial or cervical neurolocalization (P = .93). All dogs with thoracolumbar myelopathy had equivocal or higher CK levels at the lumbar collection site compared with levels at the CM collection site.

CONCLUSIONS

Cerebrospinal fluid CK values differed depending on the CSF site collection, especially in dogs with thoracolumbar myelopathy. In dogs with thoracolumbar myelopathy, CSF-CK was likely to be higher when CSF was taken from the lumbar cisterna compared with the CM cisterna. Collecting CSF from the thoracolumbar site could provide better prognostic information than if collected at the CM collection site.

Monocular Nystagmus Representing Heimann - Bielschowsky Phenomenon in a Dog With Ipsilateral Vision Loss

A 6-year-old female-neutered vaccinated Cocker Spaniel presented for preadoption neurological evaluation due to abnormal left-eye movements that had been noticed since young age. Clinical examination revealed left-eye cataract with a nonvisible left and a normal right retina on ophthalmoscopy. Neurological examination revealed absent left-sided menace response and cataract-related ipsilateral visual impairment, and intermittent left-sided abnormal eye movements consisted of intermittent, slow, coarse, variable amplitude, vertical movements of the eye that they were giving the impression of random movements of the eye within the globe as it was floating ("wandering" eye) interchangeable with periods of rest. Blood and infectious diseases tests were unremarkable. Magnetic resonance imaging of the brain was unremarkable, whilst cerebrospinal fluid analysis revealed mildly inflammatory in the light of blood contamination. A presumptive diagnosis of meningoencephalitis of unknown origin was established and trial with dexamethasone was performed, however nystagmus remained unchanged 2 weeks post-treatment. Therefore, based on the fact that monocular nystagmus existed since youth and remained static, and the dog was otherwise neurological-sign-free regardless the discontinuation of steroids, the diagnosis of meningoencephalitis was considered as unlikely and a presumptive diagnosis of Heimann - Bielschowsky phenomenon of the left eye due to cataract-related ipsilateral visual impairment was established. This vergence eye movement abnormality also known as searching, wandering or amaurotic nystagmus is a constant or intermittent benign eye movement abnormality mostly related with vision impairment due to ophthalmological or neurological disease. Heimann - Bielschowsky phenomenon is an underreported eye abnormality in veterinary medicine. Although the most common type of eye movement abnormalities seen in veterinary practice is the bilateral conjugate jerk nystagmus, monocular nystagmus representing Heimann - Bielschowsky phenomenon exists in animals, it has been related with partial or complete vision impairment and it should be recognised by the clinicians.

Evaluation of cell-free DNA as a diagnostic marker in cerebrospinal fluid of dogs

OBJECTIVE

To determine whether cell-free DNA (cfDNA) was detectable in CSF samples from dogs, whether CSF sample volume impacted CSF cfDNA concentration measurement, and whether CSF cfDNA concentration was associated with CNS disease category or CSF RBC count (RBCC), nucleated cell count (NCC), or protein concentration, which could aid in the diagnosis of neurologic diseases in dogs.

SAMPLE

80 CSF samples collected from dogs with (n = 60) and without (20) clinical neurologic disease between February 2017 and May 2018.

PROCEDURES

Results for CSF RBCC, NCC, protein concentration, and cfDNA concentration were compared across CSF groups established on the basis of whether they were obtained from dogs with (case groups) or without (control group) clinical signs of neurologic disease In addition, 5 paired CSF samples representing large (3.0-mL) and small (0.5-mL) volumes, were used to evaluate whether sample volume impacted measurement of CSF cfDNA concentration.

RESULTS

cfDNA was detected in 76 of the 80 (95%) CSF samples used to evaluate parameters across disease categories and in all 5 of the paired samples used to evaluate whether sample volume impacted cfDNA quantification. There were no substantial differences in cfDNA concentrations identified between groups (on the basis of disease category or sample volume), and the CSF cfDNA concentration did not meaningfully correlate with CSF RBCC, NCC, or protein concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Although results indicated that the CSF cfDNA concentration could not be used to differentiate between categories of neurologic disease in dogs of the the present study, further investigation is warranted regarding the use of CSF analysis, including sequencing specific cfDNA mutations, for diagnosing and monitoring neurologic disease in dogs.

Evaluation of concurrent analysis of cerebrospinal fluid samples collected from the cerebellomedullary cistern and lumbar subarachnoid space for the diagnosis of steroid-responsive meningitis arteritis in dogs

OBJECTIVE

To evaluate whether concurrent analysis of CSF samples from 2 collection sites (cerebellomedullary cistern [CMC] and lumbar subarachnoid space [LSS]) versus only 1 site could improve the diagnostic sensitivity of CSF analysis for dogs with suspected steroid-responsive meningitis arteritis (SRMA).

ANIMALS

111 client-owned dogs with SRMA diagnosed at 3 veterinary referral hospitals between 2011 and 2017.

PROCEDURES

Only dogs with CSF collected from both sites (CMC and LSS) and with no previous history of corticosteroid administration were included. Medical record data and logistic regression were used to identify factors associated with having a total nucleated cell concentration (TNCC) within the reference interval in a CSF sample from 1 collection site.

RESULTS

The TNCC was within the reference interval (TNCC < 5 cells/μL) in the CSF sample from 1 collection site for 8 of 111 (7%) dogs and was only slightly high (TNCC, 5 to 9 cells/μL) in the sample from 1 or both sites for 10 (11%) other dogs. For each of these 18 dogs, results for samples from 1 site were consistent with SRMA. The proportion of CSF samples that had a TNCC within the reference interval was comparable between sites. As age increased, so did the risk of having an unremarkable TNCC in the CSF sample from 1 site, albeit only slightly (OR, 1.08; 95% confidence interval, 1.01 to 1.16).

CONCLUSIONS AND CLINICAL RELEVANCE

CSF samples from both the CMC and LSS should be analyzed when evaluating dogs with suspected SRMA to improve the chance of detecting a high TNCC.

Evaluation of the hydroxyethyl starch stabilizing agent, Vetstarch, in the preservation of canine cerebrospinal fluid samples

BACKGROUND

A challenge of cerebrospinal fluid (CSF) analysis is the time-dependent degradation of nucleated cells, impeding accurate interpretation. CSF additives have been used to delay cell degradation; however, stabilizing agents, including serum, can alter microprotein levels.

OBJECTIVES

This study aimed to determine if the hydroxyethyl starch, Vetstarch, is effective at preserving nucleated cell morphology in CSF compared with the saline diluent or serum without altering microprotein levels.

METHODS

CSF samples were collected from 26 dogs. Samples were divided into four aliquots. One aliquot was analyzed immediately (control). The remaining three aliquots were mixed with either saline, fetal calf serum, or Vetstarch before storage at 4°C. Nucleated cell differentials, protein concentrations, and cell morphology scores were analyzed 48 hours later. A cell morphology score of 1 indicated no cellular degeneration; a score of 4 indicated severe degeneration.

RESULTS

Samples stored in serum, saline, and Vetstarch exhibited poorer mean (±SD) morphology scores (2.4 ± 0.7, 2.6 ± 0.8, and 2.7 ± 0.9, respectively) compared with controls (1.9 ± 0.4). Samples stored in saline and Vetstarch demonstrated higher percentages of unrecognizable cells, with a median of 28 (range 0-100) and 27 (0-100), respectively; samples stored in serum had a median of 14 (range 0-67) unrecognizable. Microprotein levels of samples stored in Vetstarch were dependent on the method of protein analysis. Serum significantly increased microprotein levels.

CONCLUSIONS

Vetstarch does not reduce time-dependent cellular degeneration compared with the saline diluent or serum and is, therefore, not recommended as a stabilizing agent for canine cerebrospinal fluid.

Cerebrospinal Fluid Characterization in Cynomolgus Monkeys, Beagle Dogs, and Göttingen Minipigs

Intrathecal administration is an important route for drug delivery, and in pharmacology and toxicology studies, cerebrospinal fluid (CSF) collection and analysis is required for evaluating blood–brain barrier penetration and central nervous system exposure. The characteristics of CSF in commonly used nonrodent models are lacking. The purpose of this study is to evaluate and provide some insights into normal cellular and biochemical composition of CSF as well as diffusion potential following intrathecal injection across several nonrodent species. Cerebrospinal fluid samples were collected from the cerebellomedullary cistern of beagle dogs, cynomolgus monkeys, and Göttingen minipigs and analyzed for clinical chemistry and cytological evaluation. Diffusion into the intrathecal space following intrathecal injection was assessed following administration of a contrast agent using fluoroscopy. The predominant cell types identified in CSF samples were lymphocytes and monocytoid cells; however, lymphocytes were represented in a higher percentage in dogs and monkeys as opposed to monocytoid cells in minipigs. Clinical chemistry parameters in CSF revealed higher Cl⁻ concentrations than plasma, but lower K⁺, Ca²⁺, phosphorus, glucose, creatinine, and total protein levels consistent across all 3 species. Diffusion rates following intrathecal injection of iodixanol showed some variability with dogs, showing the greatest diffusion distance; however, the longest diffusion time through the intervertebral space, followed by monkeys and minipigs. Minimal diffusion was observed in minipigs, which could have been attributed to anatomical spinal constraints that have been previously identified in this species.

Comparison of cerebellomedullary and lumbar cerebrospinal fluid analysis in dogs with neurological disease

Background

Cerebrospinal fluid (CSF) analysis aids in categorizing underlying disease processes in patients with neurologic disease. Convention suggests that CSF should be collected caudal to the lesion. However, little evidence exists to justify this assertion.

Hypothesis/Objectives

Evaluate the clinicopathologic differences between CSF collected from the cerebellomedullary (CM) and lumbar cisterns in dogs presented for evaluation of neurologic disease.

Animals

Fifty‐one client‐owned dogs undergoing magnetic resonance imaging (MRI) and CSF collection for investigation of neurologic disease.

Methods

Cerebrospinal fluid was prospectively collected from the CM and lumbar cisterns in all patients. The total protein (TP) concentration, red blood cell (RBC) count, and total nucleated cell count (TNCC) were analyzed within 30 minutes of collection. Results and cytology findings were interpreted by a single pathologist.

Results

Fifty‐one paired samples were collected. The TNCC (P < .001), RBC (P < .001), and TP (P < .001) were different between collection sites. When grouped by neurolocalization, TP (intracranial, P < .001; cervical, P < .001; thoracolumbar, P < .001) and RBC (intracranial, P < .001; cervical, P ≤ .002; thoracolumbar, P = .006) counts were significantly different. The TNCC was significantly different in the cervical (P = .04) and thoracolumbar localizations (P = .004) but not for intracranial (P = .30) localizations. The pathologist's interpretation differed between sites in 66.7% of the cases (34/51).

Conclusions

In dogs with lesions that neurolocalized to the brain or cervical spinal cord, there may be clinical benefit in collecting fluid from both the CM and lumbar cisterns. In dogs with thoracolumbar myelopathy, CSF collected from the CM cistern may not be representative of the underlying disease process.

Cerebrospinal fluid and blood lactate concentrations as prognostic biomarkers in dogs with meningoencephalitis of unknown origin

Meningoencephalitis of unknown origin (MUO) is a common inflammatory disease of the central nervous system. Several studies investigated finding prognostic factors, but results are contradictory. The aim of this study was to determine the concentrations of blood lactate (Blood-L) and cerebrospinal fluid lactate (CSF-L) in dogs with MUO for prognostic purposes. A total of 45 dogs with MUO (MUO group) and 11 with idiopathic epilepsy (IE group) were included. In the MUO group, 22 dogs were treated with prednisolone + cytosine arabinoside, 17 with prednisolone ± cyclosporine, and six received no treatment. In the MUO group, there was a strong-moderate positive correlation between Blood-L and CSF-L (ρ = 0.63557; P < 0.0001), a strong-moderate negative correlation between survival and CSF-L (ρ= -0.50210; P < 0.0004), and a weak negative correlation between survival and Blood-L (ρ= -0.35685; P < 0.0220). Dogs with a favourable response to treatment at 1 month had lower initial concentrations of Blood-L and CSF-L (P < 0.0010; P < 0.0037), and those with a worse response had higher values (P < 0.0497; P < 0.0004). Dogs that remained stable with treatment showed lower CSF-L concentrations (P < 0.0013). Dogs with Blood-L>4 mmol/L (P < 0.03) and/or CSF-L> 4 mmol/L (P < 0.009) had lower survival rates with the latter also showing more severe signs, probably indicating severe neuronal damage. These findings suggest that concentrations of CSF-L and Blood-L in dogs with MUO could be used as prognostic indicators.

Effects of stylet-in versus stylet-out collection of cerebrospinal fluid from the cisterna magna on contamination of samples, sample quality, and collection time

OBJECTIVE

To evaluate safety of stylet-in and stylet-out techniques for collection of CSF from the cisterna magna and to assess whether there were differences between techniques with regard to contamination of samples, sample quality, and efficiency of collection.

ANIMALS

10 adult purpose-bred research Beagles.

PROCEDURES

A prospective crossover study was conducted. Preanesthetic physical and neurologic examinations and hematologic analyses were performed. Dogs were anesthetized, and collection of CSF samples from the cisterna magna by use of a stylet-in or stylet-out technique was performed. Two weeks later, samples were collected with the other sample collection technique. Samples of CSF were processed within 1 hour after collection.

RESULTS

Cellular debris was detected in higher numbers in stylet-in samples, although this did not affect sample quality. The stylet-out technique was performed more rapidly. No adverse effects were detected for either technique.

CONCLUSIONS AND CLINICAL RELEVANCE

Both techniques could be safely performed in healthy anesthetized dogs. The stylet-out technique was performed more rapidly and yielded a sample with less cellular debris. Both techniques can be used in clinical practice to yield CSF samples with good diagnostic quality.

Risk factors for blood-contaminated cerebrospinal fluid collection in dogs

OBJECTIVE

To determine the risk factors for blood contamination during cerebrospinal fluid (CSF) collection in dogs.

STUDY DESIGN AND METHODS

This is a prospective study of 170 CSF samples. Data collected included signalment of the patient, body condition score, site of CSF collection (cerebellomedullary cistern (CMC) or lumbar cistern (LC)), number of attempts, clinician expertise, final diagnosis, time of day, skull conformation and day of the week. Analysis of the CSF samples was then performed, and the presence of blood contamination (red blood cells >500/µl) was recorded. Logistic regression was used to quantify the association of potential risk factors of the procedure. Multivariate analysis was performed on the variables that were statistically significant.

RESULTS

Of the 170 CSF samples, 53 per cent were collected from the CMC (n=90) and 47 per cent from the LC (n=80). Blood contamination was seen in 20 per cent (n=34) of the samples, 8.9 per cent (n=8) in CMC and 32.5 per cent (n=26) in LC samples. Increased odds of obtaining a contaminated CSF sample were associated with lower level of clinician expertise (odds ratio: 2.5; 95 per cent confidence interval: 0.9-6.7; P=0.046) and with LC versus CMC collection site (odds ratio: 8.1; 95 per cent confidence interval: 2.1-12.9; P=0.001).

CLINICAL SIGNIFICANCE

There is increased likelihood of blood contamination when collecting CSF from the LC compared with the CMC site. Increased clinician experience reduced the risk of CSF blood contamination, but none of the other variables examined significantly influenced this.

Diagnostic value of cerebrospinal fluid analysis in a population of dogs with suspected idiopathic epilepsy

Cerebrospinal fluid (CSF) analysis is commonly used in the diagnostic investigation of seizure disorders in order to exclude possible inflammatory underlying aetiology. The medical records were searched for dogs presenting with epileptic seizures (ES) that had normal interictal neurological examination, normal complete blood count and biochemistry analysis, unremarkable MRI of the brain and had CSF analysis performed as part of the diagnostic investigation. A total of 200 dogs met the inclusion criteria. The CSF was abnormal in 30 dogs with a median total nucleated cell count of two cells/µl (IQR 1.5-6) and median protein concentration of 0.37 g/l (IQR 0.31-0.41). Pleocytosis was recorded in 14/30 dogs and the CSF protein was increased in 22/30. There was no correlation between abnormal CSF and the type or number of seizures or the time interval between the last seizure and CSF collection. A significant correlation was found between the number of red blood cells on CSF and having an abnormal CSF. The prevalence of having a diagnosis other than suspected idiopathic epilepsy (IE) was 0.5 per cent (1/200). These results suggest that performing CSF analysis in dogs with recurrent ES that have normal interictal neurological examination and unremarkable MRI has a low diagnostic value.

CSF omeprazole concentration and albumin quotient following high dose intravenous omeprazole in dogs

Clinical signs of syringomyelia and hydrocephalus occur secondary to cerebrospinal fluid (CSF) accumulation within the central nervous system. Omeprazole is recommended to treat these conditions despite little evidence of its capacity to decrease CSF production in the dog. Studies into new treatments are hampered by difficulties in measuring CSF production. The albumin quotient (QAlb), the ratio between CSF and serum albumin concentrations, may reflect CSF production and any decrease in CSF production should be associated with an increase in QAlb. The primary objective of this study was to determine CSF omeprazole concentration after administration of a high intravenous dose of omeprazole and to evaluate its impact on QAlb in the dog. The second aim was to validate QAlb as a surrogate marker of CSF production. Eighteen dogs were included in this prospective crossover placebo-controlled study. Each dog received omeprazole (10 mg/kg), acetazolamide (50 mg/kg) combined with furosemide (1 mg/kg) and saline. Blood and CSF samples were obtained on day 0 and then every 7 days, one hour after drug administration. Omeprazole concentrations (2.0 ± 0.4 μmol/L) reached in CSF after high dose omeprazole were lower than the concentrations previously described as decreasing CSF production in dogs. There was no significant increase in QAlb following administration of acetazolamide/furosemide, prohibiting validation of QAlb as a surrogate marker for CSF production. Several dogs presented transient mild side effects after injection of acetazolamide/furosemide. High dose omeprazole was well tolerated in all dogs.

Collection of cerebrospinal fluid into EDTA versus plain tubes does not affect the standard analysis in dogs

BACKGROUND

Cerebrospinal fluid (CSF) can be collected into ethylenediaminetetraacetic acid (EDTA) or plain tubes. The EDTA content presumably contributes to a better cell preservation. EDTA, however, is reported to cause a false elevation in the total protein concentration and to dilute the CSF sample, thereby affecting the diagnostic interpretation. To the authors' knowledge, no validated studies support this view. The aim of this study was therefore to determine if the choice of tube (EDTA or plain) influences the results of the standard CSF analysis.

RESULTS

Thirty-two paired EDTA stabilised and plain CSF samples were included. There was no statistically significant difference in the semi-quantitative protein concentrations when comparing CSF samples from EDTA and plain plastic tubes (P > 0.99). The total nucleated cell count did not differ significantly between EDTA and plain tube samples (P = 0.85). There were no significant differences in the differential cell counts between the two tubes when evaluating polymorphonuclear cells (P = 0.90), lymphocytes (P = 0.84) and monocytes/macrophages (P = 0.86). Also, there was no significant difference in the preservation of cell morphology when evaluating cytological preparations from EDTA stabilised and plain tube samples (P = 0.45).

CONCLUSIONS

The collection of CSF into EDTA tubes does not influence the result of the standard CSF analysis. However, a presumed positive effect of EDTA on cell preservation could not be shown in the present study.