Hyperacute Vasospasm After Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Cerebral vasospasm after aneurysmal subarachnoid hemorrhage typically occurs 3-14 days after aneurysm rupture. We describe a series of patients who developed vasospasm within minutes of aneurysm rupture. This phenomenon, which we term, "hyperacute vasospasm," has been reported in animal models of SAH, but hitherto has been poorly described in humans. METHODS: Eleven patients were identified from an institutional registry who had aneurysmal rupture during catheter cerebral angiography between 1997 and 2009. We quantified the degree of vasoconstriction using vascular diameter index (VDI). The change in VDI (delta VDI or DVDI) was calculated by determining the difference in VDI before and after the procedure. We also examined the relationship between hyperacute vasospasm and delayed cerebral ischemia. RESULTS: Ten of eleven (91%) patients with intraoperative aneurysm rupture had cerebral vasoconstriction within minutes of intra-procedural aneurysmal rupture. Six of eleven patients (55%) with hyperacute vasospasm developed delayed cerebral infarction. CONCLUSIONS: Hyperacute vasospasm is likely common in patients with intraoperative aneurysm rupture and may be an unrecognized element of the natural history of aneurysmal subarachnoid hemorrhage. In this limited series, there was an association between hyperacute vasospasm and delayed cerebral infarction.

Quantitative magnetic resonance imaging in a naturally occurring canine model of spinal cord injury.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: To analyze magnetic resonance imaging (MRI) evaluator agreement in dogs with spinal cord injury (SCI) caused by intervertebral disk herniation (IVDH) using semiautomated and manual lesion segmentation and to analyze the associations between MRI and functional outcome. SETTING: United States of America. METHODS: T2-weighted MRIs from dogs with SCI resulting from thoracolumbar IVDH were identified from a database. Evaluators categorized MRIs on the basis of the presence or absence of a T2-hyperintense spinal cord lesion in axial and sagittal images. A semiautomated segmentation algorithm was developed and used to estimate the lesion volume. Agreement between evaluators and between semiautomated and manual segmentation was analyzed. The relationships of qualitative and quantitative MRIs with behavioral functional outcome were analyzed. RESULTS: Axial images more commonly depicted lesions compared with sagittal images. Lesions in axial images had more consistent associations with functional outcome compared with sagittal images. There was imperfect qualitative agreement, and lesion volume estimation was imprecise. However, there was improved precision using semiautomated segmentation compared with manual segmentation. CONCLUSION: Lesion volume estimation in dogs with naturally occurring SCI caused by IVDH is challenging, and axial images have important advantages compared with sagittal images. The semiautomated segmentation algorithm described herein shows promise but may require further refinement.

Red Blood Cell Distribution Width is Associated with Poor Clinical Outcome After Subarachnoid Hemorrhage: A Pilot Study.

INTRODUCTION: The red cell distribution width (RDW) is a biomarker strongly associated with poor outcome in inflammatory and thrombotic diseases. Subarachnoid hemorrhage (SAH) is both an inflammatory and thrombotic state in which many biomarkers have been studied. In this exploratory pilot study, we sought to determine whether RDW predicts poor outcome in patients with SAH. METHODS: Patients with moderate-to-severe SAH were prospectively enrolled in an observational study of biomarkers and outcome. CBC, ESR, high sensitivity CRP, D-dimer, and fibrinogen were obtained on post-bleed days (PBD) 1, 3, 5, 7, and 10. Poor outcome was defined as a modified Rankin score of 3-6 at 90-days. RESULTS: Of 40 patients, 5 (12.5%) died and 19 (47.5%) had a poor outcome. RDW (p = 0.046) when measured serially over the study period, was significantly higher among patients with poor outcome. Maximum RDW (OR 2.3 95% CI 1.2-3.6; p = 0.014) and maximum WBC count (OR 1.29 95% CI 1.04-1.60; p = 0.018) were associated with poor outcome. Stepwise addition of maximum ESR, CRP, D-dimer, and fibrinogen yielded a model with RDW (OR 2.54 95% CI 1.21-5.35; p = 0.014) and fibrinogen (OR 1.01 95% CI 1.002-1.01; p = 0.004) predicting outcome. With addition of age and Hunt and Hess grade, RDW, fibrinogen, and high-grade status remained significantly associated with poor outcome. Use of PBD1 RDW in lieu of maximum RDW, resulted in a similar model. CONCLUSIONS: An elevated RDW is associated with poor outcome in SAH patients. RDW may be a useful predictor of outcomes after SAH.

Transduction efficiency of neurons and glial cells by AAV-1, -5, -9, -rh10 and -hu11 serotypes in rat spinal cord following contusion injury.

Adeno-associated viruses (AAVs) are a promising system for therapeutic gene delivery to neurons in a number of neurodegenerative conditions including spinal cord injuries (SCIs). Considering the role of macrophages and glia in the progression of 'secondary damage', we searched for the optimal vectors for gene transfer to both neurons and glia following contusion SCI in adult rats. Contusion models share many similarities to most human spinal cord traumas. Several AAV serotypes known for their neuronal tropism expressing enhanced green-fluorescent protein (GFP) were injected intraspinally following thoracic T10 contusion. We systematically compared the transduction efficacy and cellular tropism of these vectors for neurons, macrophages/microglia, oligodendrocytes, astrocytes and NG2-positive glial cells following contusion SCI. No additional changes in inflammatory responses or behavioral performance were observed for any of the vectors. We identified that AAV-rh10 induced robust transduction of both neuronal and glial cells. Even though efficacy to transduce neurons was comparable to already established AAV-1, AAV-5 and AAV-9, AAV-rh10 transduced significantly higher number of macrophages/microglia and oligodendrocytes in damaged spinal cord compared with other serotypes tested. Thus, AAV-rh10 carries promising potential as a gene therapy vector, particularly if both the neuronal and glial cell populations in damaged spinal cord are targeted.

Native shrub reestablishment in exotic annual grasslands: do ecosystem processes recover?

The impacts of exotic plant species on ecosystem processes are well established, motivating numerous efforts to facilitate native-species recovery. Nonetheless, how the return of native species influences ecosystem processes and how these changes feed back to influence the recovery process are poorly understood. We examined these questions in exotic annual grasslands on Santa Cruz Island, California, USA, where the removal of nonnative herbivores has led to the recovery of the native shrubs Artemisia californica and Eriogonum arborescens. To examine the influence of shrub colonization on nutrient cycling, and the mechanisms by which these changes arise, we measured available nitrogen and phosphorus, and quantified nitrogen mineralization and litterfall rates under shrubs and grasses in the field and in experimental monoculture plots. Both native shrubs altered nitrogen cycling as they colonized the grassland, but they did so in opposite directions. Eriogonum depressed nitrogen pools and mineralization rates via large inputs of nitrogen-poor litter. In contrast Artemisia increased nitrogen and phosphorus pools and nitrogen mineralization rates. Last, to determine if shrub effects on soils favor shrubs or grasses, we conducted a nitrogen and phosphorus fertilization experiment in the field. Only the exotic grass was significantly limited by nitrogen. Thus the depressed nitrogen availability associated with Eriogonum colonization is more harmful to exotic grasses than to the native shrub. By contrast, the elevated nitrogen associated with recovering Artemisia favors grasses over the shrub, possibly hindering recovery of the native. Mechanistic studies of the ecosystem ,impacts of native-plant recovery are useful for managers wishing to predict which native species return ecosystem function, and whether such changes feed back to influence native recovery.

Cerebrospinal fluid myelin basic protein as a prognostic biomarker in dogs with thoracolumbar intervertebral disk herniation.

BACKGROUND: Release of myelin basic protein (MBP) into the cerebrospinal fluid (CSF) is associated with active demyelination and correlates with outcome in various neurological diseases. HYPOTHESIS/OBJECTIVES: To describe associations among CSF MBP concentration, initial neurological dysfunction, and long-term ambulatory outcome in dogs with acute thoracolumbar intervertebral disk herniation (IVDH). ANIMALS: Fifty seven [corrected] dogs with acute thoracolumbar IVDH and 16 clinically normal dogs. METHODS: Prospective case series clinical study. Signalment, initial neurological dysfunction as determined by a modified Frankel score (MFS), and ambulatory outcome at >3-month follow-up were recorded. Cisternal CSF MBP concentration was determined by an ELISA. Associations were estimated between CSF MBP concentration and various clinical parameters. RESULTS: Dogs with thoracolumbar IVDH that did not ambulate at follow-up had a higher CSF MBP concentration (median, 3.56 ng/mL; range, 0.59-51.2 ng/mL) compared with control dogs (median, 2.22 ng/mL; range, 0-3.82 ng/mL) (P=.032). A CSF MBP concentration of >or=3 ng/mL had a sensitivity of 78% and specificity of 76% to predict an unsuccessful outcome based on receiver-operating characteristics curve analysis (area under the curve=0.688, P=.079). Affected dogs with a CSF MBP concentration>or=3 ng/mL had 0.09 times the odds of ambulation at follow-up compared with affected dogs with CSF MBP concentration<3 ng/mL when adjusted for initial MFS (95% confidence interval 0.01-0.66, P=.018). CONCLUSIONS AND CLINICAL IMPORTANCE: These results would suggest that CSF MBP concentration may be useful as an independent prognostic indicator in dogs with thoracolumbar IVDH.

Evaluation of brain tissue or cerebrospinal fluid with broadly reactive polymerase chain reaction for Ehrlichia, Anaplasma, spotted fever group Rickettsia, Bartonella, and Borrelia species in canine neurological diseases (109 cases).

BACKGROUND: Vector-transmitted microorganisms in the genera Ehrlichia, Anaplasma, Rickettsia, Bartonella, and Borrelia are commonly suspected in dogs with meningoencephalomyelitis (MEM), but the prevalence of these pathogens in brain tissue and cerebrospinal fluid (CSF) of dogs with MEM is unknown. HYPOTHESIS/OBJECTIVES: To determine if DNA from these genera is present in brain tissue and CSF of dogs with MEM, including those with meningoencephalitis of unknown etiology (MUE) and histopathologically confirmed cases of granulomatous (GME) and necrotizing meningoencephalomyelitis (NME). ANIMALS: Hundred and nine dogs examined for neurological signs at 3 university referral hospitals. METHODS: Brain tissue and CSF were collected prospectively from dogs with neurological disease and evaluated by broadly reactive polymerase chain reaction (PCR) for Ehrlichia, Anaplasma, Spotted Fever Group Rickettsia, Bartonella, and Borrelia species. Medical records were evaluated retrospectively to identify MEM and control cases. RESULTS: Seventy-five cases of MUE, GME, or NME, including brain tissue from 31 and CSF from 44 cases, were evaluated. Brain tissue from 4 cases and inflammatory CSF from 30 cases with infectious, neoplastic, compressive, vascular, or malformative disease were evaluated as controls. Pathogen nucleic acids were detected in 1 of 109 cases evaluated. Specifically, Bartonella vinsonii subsp. berkhoffii DNA was amplified from 1/6 dogs with histopathologically confirmed GME. CONCLUSION AND CLINICAL IMPORTANCE: The results of this investigation suggest that microorganisms in the genera Ehrlichia, Anaplasma, Rickettsia, and Borrelia are unlikely to be directly associated with canine MEM in the geographic regions evaluated. The role of Bartonella in the pathogenesis of GME warrants further investigation.

Effect of mannitol and hypertonic saline on cerebral oxygenation in patients with severe traumatic brain injury and refractory intracranial hypertension.

BACKGROUND: The impact of osmotic therapies on brain oxygen has not been extensively studied in humans. We examined the effects on brain tissue oxygen tension (PbtO(2)) of mannitol and hypertonic saline (HTS) in patients with severe traumatic brain injury (TBI) and refractory intracranial hypertension. METHODS: 12 consecutive patients with severe TBI who underwent intracranial pressure (ICP) and PbtO(2) monitoring were studied. Patients were treated with mannitol (25%, 0.75 g/kg) for episodes of elevated ICP (>20 mm Hg) or HTS (7.5%, 250 ml) if ICP was not controlled with mannitol. PbtO(2), ICP, mean arterial pressure, cerebral perfusion pressure (CPP), central venous pressure and cardiac output were monitored continuously. RESULTS: 42 episodes of intracranial hypertension, treated with mannitol (n = 28 boluses) or HTS (n = 14 boluses), were analysed. HTS treatment was associated with an increase in PbtO(2) (from baseline 28.3 (13.8) mm Hg to 34.9 (18.2) mm Hg at 30 min, 37.0 (17.6) mm Hg at 60 min and 41.4 (17.7) mm Hg at 120 min; all p<0.01) while mannitol did not affect PbtO(2) (baseline 30.4 (11.4) vs 28.7 (13.5) vs 28.4 (10.6) vs 27.5 (9.9) mm Hg; all p>0.1). Compared with mannitol, HTS was associated with lower ICP and higher CPP and cardiac output. CONCLUSIONS: In patients with severe TBI and elevated ICP refractory to previous mannitol treatment, 7.5% hypertonic saline administered as second tier therapy is associated with a significant increase in brain oxygenation, and improved cerebral and systemic haemodynamics.

Rat optic nerve oligodendrocytes develop in the absence of viable retinal ganglion cell axons.

Retinal ganglion cell axons and axonal electrical activity have been considered essential for migration, proliferation, and survival of oligodendrocyte lineage cells in the optic nerve. To define axonal requirements during oligodendrogenesis, the developmental appearance of oligodendrocyte progenitors and oligodendrocytes were compared between normal and transected optic nerves. In the absence of viable axons, oligodendrocyte precursors migrated along the length of the nerve and subsequently multiplied and differentiated into myelin basic protein-positive oligodendrocytes at similar densities and with similar temporal and spatial patterns as in control nerves. Since transected optic nerves failed to grow radially, the number of oligodendrocyte lineage cells was reduced compared with control nerves. However, the mitotic indices of progenitors and the percentage of oligodendrocytes undergoing programmed cell death were similar in control and transected optic nerves. Oligodendrocytes lacked their normal longitudinal orientation, developed fewer, shorter processes, and failed to form myelin in the transected nerves. These data indicate that normal densities of oligodendrocytes can develop in the absence of viable retinal ganglion axons, and support the possibility that axons assure their own myelination by regulating the number of myelin internodes formed by individual oligodendrocytes.

The tissue plasminogen activator (tPA)/plasmin extracellular proteolytic system regulates seizure-induced hippocampal mossy fiber outgrowth through a proteoglycan substrate.

Short seizure episodes are associated with remodeling of neuronal connections. One region where such reorganization occurs is the hippocampus, and in particular, the mossy fiber pathway. Using genetic and pharmacological approaches, we show here a critical role in vivo for tissue plasminogen activator (tPA), an extracellular protease that converts plasminogen to plasmin, to induce mossy fiber sprouting. We identify DSD-1-PG/phosphacan, an extracellular matrix component associated with neurite reorganization, as a physiological target of plasmin. Mice lacking tPA displayed decreased mossy fiber outgrowth and an aberrant band at the border of the supragranular region of the dentate gyrus that coincides with the deposition of unprocessed DSD-1-PG/phosphacan and excessive Timm-positive, mossy fiber termini. Plasminogen-deficient mice also exhibit the laminar band and DSD- 1-PG/phosphacan deposition, but mossy fiber outgrowth through the supragranular region is normal. These results demonstrate that tPA functions acutely, both through and independently of plasmin, to mediate mossy fiber reorganization.

Species diversity and biological invasions: relating local process to community pattern.

In a California riparian system, the most diverse natural assemblages are the most invaded by exotic plants. A direct in situ manipulation of local diversity and a seed addition experiment showed that these patterns emerge despite the intrinsic negative effects of diversity on invasions. The results suggest that species loss at small scales may reduce invasion resistance. At community-wide scales, the overwhelming effects of ecological factors spatially covarying with diversity, such as propagule supply, make the most diverse communities most likely to be invaded.

Observational learning and social facilitation in the rat.

Learning by rats was facilitated when response-relevant cues were provided by other rats; learning increased as a function of number of cues provided. These results suggest that rats can learn by imitation. Learning by rats that observed conspecifics not emitting response-relevant cues was retarded compared to learning by rats that did not observe conspecifics. This indicates that a conspecific's presence can also inhibit learning, a result consistent with social facilitation theory.

Induction of altered c-src product during neural differentiation of embryonal carcinoma cells.

The expression of the cellular src gene product pp60c-src was examined in an embryonal carcinoma cell line that differentiates in vitro into neuronlike cells after being treated with retinoic acid. Quantitative and qualitative changes in c-src expression accompanied the events associated with neuronal differentiation. The levels of pp60c-src increased 8- to 20-fold during the period when the cells elaborated neuritic processes and expressed neuron-specific proteins. The electrophoretic mobility of pp60c-src induced in these cells was retarded in comparison with that in untreated cells or in treated cells before neurite elaboration. The shift in electrophoretic mobility was due to an alteration in the amino terminal 16,000 daltons of pp60c-src and similar to an alteration of c-src protein found in neural tissues and in pure primary cultures of neuronal cells. These results indicate that expression of pp60c-src induced by retinoic acid in these embryonal carcinoma cells mimics the expression of c-src in developing neurons. Therefore, this embryonal carcinoma cell line provides a model system to investigate the function of the src protein in neuronal differentiation.

Magnetic resonance imaging characteristics of necrotizing meningoencephalitis in Pug dogs.

BACKGROUND: The magnetic resonance imaging (MRI) characteristics of necrotizing meningoencephalitis (NME) are not well documented. OBJECTIVES: To describe common MRI features of NME, to compare the MRI features to histopathologic findings, and to determine whether or not MRI lesions are predictive of survival time. ANIMALS: Eighteen Pugs with NME. METHODS: Retrospective MRI case study of Pugs identified by a search of medical records at 6 veterinary institutions. Eighteen dogs met inclusion criteria of histopathologically confirmed NME and antemortem MRI exam. MRI lesions were characterized and compared with histopathology with the kappa statistic. Survival times were compared with MRI findings by use of Mann-Whitney U-tests and Spearman's rho. RESULTS: Twelve of 18 lesions were indistinctly marginated with mild parenchymal contrast enhancement. Prosencephalic (17/18) lesion distribution included the parietal (16/18), temporal (16/18), and occipital (16/18) lobes. There were cerebellar (4/18) and brainstem (3/18) lesions. Asymmetric lesions were present in both gray and white matter in all dogs. Falx cerebri shift was common (11/18), and 6 dogs had brain herniation. Leptomeningeal enhancement was present in 9/18 dogs. A moderate positive association was found between parenchymal contrast enhancement and both necrosis (kappa= 0.45; P= .045) and monocytic inflammation (kappa= 0.48; P= .025). Higher MRI lesion burden was correlated with longer time from disease onset to MRI (P= .045). MRI lesion burden did not correlate to survival time. CONCLUSIONS AND CLINICAL IMPORTANCE: Asymmetric prosencephalic grey and white matter lesions with variable contrast enhancement were consistent MRI changes in Pugs with confirmed NME. While not pathognomonic for NME, these MRI characteristics should increase confidence in a presumptive diagnosis of NME in young Pugs with acute signs of neurologic disease.

Magnetic resonance imaging in dogs with neurologic impairment due to acute thoracic and lumbar intervertebral disk herniation.

BACKGROUND: Magnetic resonance imaging (MRI) is a correlate to physical examination in various myelopathies and a predictor of functional outcome. OBJECTIVES: To describe associations among MRI features, neurological dysfunction before MRI, and functional outcome in dogs with disk herniation. ANIMALS: One hundred and fifty-nine dogs with acute thoracolumbar disk herniation. METHODS: Retrospective case series. Signalment, initial neurological function as assessed by a modified Frankel score (MFS), and ambulatory outcome at hospital discharge and >3 months (long-term) follow-up were recorded from medical records and telephone interview of owners. Associations were estimated between these parameters and MRI signal and morphometric data. RESULTS: Dogs with intramedullary T2W hyperintensity had more severe pre-MRI MFS (median 2, range 0-4) and lower ambulatory proportion at long-term follow-up (0.76) than those dogs lacking hyperintensity (median MFS 3, range 0-5; ambulatory proportion, 0.93) (P=.001 and .013, respectively). Each unit of T2W length ratio was associated with a 1.9 times lower odds of long-term ambulation when adjusted for pre-MRI MFS (95% confidence interval 1.0-3.52, P=.05). Dogs with a compressive length ratio >1.31 (which was the median ratio within this population) had more severe pre-MRI MFS (median 3, range 0-5) compared with those with ratios < or =1.31 (median MFS 3, range 0-4; P=.006). CONCLUSIONS AND CLINICAL IMPORTANCE: MRI features were associated with initial injury severity in dogs with thoracolumbar disk herniation. Based on results of this study, the T2W length ratio and presence of T2W intramedullary hyperintensity appear to be predictive of long-term ambulatory status.

Cervical vertebral malformation-malarticulation syndrome in the Bernese mountain dog: clinical and magnetic resonance imaging features.

OBJECTIVES: To describe the clinical and magnetic resonance imaging features of cervical vertebral malformation-malarticulation in Bernese mountain dogs. METHODS: Seven Bernese mountain dogs (four males and three females) were diagnosed with cervical vertebral malformation-malarticulation by magnetic resonance imaging. The following data were evaluated retrospectively: (1) abnormalities of the cervical vertebral column and spinal cord, (2) spinal cord compression, (3) intervertebral disc degeneration and herniation, (4) severity of clinical signs pretreatment and after treatment, (5) type of treatment and (6) outcome. RESULTS: Spin echo T1-weighted and T2-weighted images disclosed multi-level, extradural compressive spinal cord lesions (ventral, dorsolateral or both) spanning from intervertebral disc spaces C3-4 to C6-7. In all seven dogs, T2-weighted images disclosed one or more intramedullary hyperintensities associated with extradural spinal cord compression. Surgery was performed in five dogs. Two dogs were managed medically. The prognosis for surgical or conservative management in Bernese mountain dogs was similar to cervical vertebral malformation-malarticulation in other breeds. CLINICAL SIGNIFICANCE: Cervical vertebral malformation-malarticulation is an important differential diagnosis for young to middle-aged Bernese mountain dogs with a C1-5 or C6-T2 neuroanatomic localisation. Dorsolateral spinal cord compression associated with articular process hypertrophy was the most common feature of cervical vertebral malformation-malarticulation in the seven Bernese mountain dogs evaluated.

Neuronal influences on glial progenitor cell development.

The role of cell-cell interactions in the development of bipotential glial progenitor cells in cultures of rat cerebellum and optic nerve was studied. In the cerebellar cultures, progenitor cells divide slowly and most of their progeny develop into additional progenitor cells. Progenitor cells isolated from postconfluent cultures of cerebellum, however, develop rapidly into oligodendrocytes when grown in a serum-free medium. Factors secreted or shed into the medium by young cerebellar interneurons stimulate optic nerve progenitor cells to divide and promote the survival of progenitor cells. These factors appear to alter the function of the internal clock that regulates the timing of oligodendrocyte differentiation. These results suggest that the neuronal microenvironment can influence the lineage decisions of multipotential glial progenitor cells.

Epidemiology of necrotizing meningoencephalitis in Pug dogs.

BACKGROUND: Although the histopathologic features of necrotizing meningoencephalitis (NME) have been described previously, little information is available concerning the signalment, geographic distribution, seasonal onset, treatment, and survival of affected dogs. ANIMALS: Sixty Pugs with NME and 14 contemporaneous control Pugs with other intracranial diseases (non-NME group). METHODS: Pugs that were euthanized or died because of intracranial disease were prospectively obtained. All dogs had necropsy, histopathology, and testing for various infectious diseases and were subsequently divided into NME and non-NME groups. Signalment, geographic distribution, seasonal onset, treatment, and survival were compared between groups. RESULTS: In Pugs with NME, median age at onset of clinical signs was 18 months (range, 4-113 months). A greater proportion of female dogs were present in the NME group (40/60) compared with the control group (6/14). Pugs with NME had a significantly lower mean weight (7.81 kg) than control Pugs (9.79 kg) (P= .012). Mean survival in Pugs with NME was 93 days (range, 1-680 days), with dogs receiving any form of treatment living significantly longer than those that were not treated (P= .003). Anticonvulsive drugs were the only treatment significantly associated with longer survival (P= .003). CONCLUSIONS AND CLINICAL IMPORTANCE: NME appears to be a common cause of intracranial signs in Pugs, based on the high proportion of NME dogs reported in this population. Pugs with NME are most commonly young adult female dogs. Although further investigation is needed to determine the optimal treatment of NME, anticonvulsive drugs appear to beneficially affect duration of survival.

Meningomyelitis in dogs: a retrospective review of 28 cases (1999 to 2007).

OBJECTIVES: To characterise dogs with meningomyelitis and to compare signalment, body temperature and vaccination status to a representative control group. METHODS: Dogs with meningomyelitis were identified retrospectively. Signalment, history, vaccination status, body temperature, severity of neurological dysfunction (modified Frankel score), diagnostic procedures, aetiology, survival to discharge and long-term survival were analysed. RESULTS: Affected dogs were younger (P<0.05) and more frequently hound or toy breeds (P<0.05) when compared with controls. Hound and toy breed dogs less than or equal to three years of age had a 13 times higher odds of meningomyelitis compared with other breeds (P<0.001). General proprioceptive ataxia, limb paresis and paraspinal hyperaesthesia were the most common clinical signs. Meningomyelitis of unknown aetiology and granulomatous meningomyelitis were the most common diagnoses. The median time to death or continued follow-up in dogs alive at discharge was 213 days. Meningomyelitis resulted in death or euthanasia in 14 of 28 dogs. Clinical signs improved or resolved in seven of 28 dogs. CLINICAL SIGNIFICANCE: Meningomyelitis is a differential diagnosis for dogs with clinical signs of myelopathy. Young dogs and toy or hound breeds seem to be predisposed. Clinical signs of meningomyelitis improve or resolve in some dogs.

Putative Cerebral Microbleeds in Dogs Undergoing Magnetic Resonance Imaging of the Head: A Retrospective Study of Demographics, Clinical Associations, and Relationship to Case Outcome.

BACKGROUND: Cerebral microbleeds (CMBs) are focal intraparenchymal signal voids on gradient-echo magnetic resonance imaging (MRI), corresponding to regions of chronic hemorrhage. In humans, they are associated with systemic disease and shorter survival times. Although similar findings have been identified in dogs, their epidemiology and clinical correlations have not been investigated. OBJECTIVE: To determine epidemiological features, clinical associations, and associations with outcome for putative CMB-like foci (putative microbleeds [pMBs]) identified by T2*-weighted MRI in dogs. ANIMALS: Five hundred and eighty-two dogs undergoing 3T brain MRI between 2011 and 2016. METHODS: Retrospective case-control study. Demographic, diagnostic, and clinicopathological data were obtained from medical records and phone follow-up. Demographic variables were compared between dogs with and without evidence of pMBs. For dogs with such evidence, and a subset of matched controls, associations with clinical presentation, concurrent disease, and survival times were evaluated. RESULTS: Dogs with pMBs were older (P < .001) and smaller (P = .004) than unaffected dogs. Compared to matched controls, they presented more frequently for vestibular signs (P = .030). Cortical atrophy occurred concurrently with pMBs in 26% (14/54) of dogs. Diagnosed renal disease was not significantly associated with pMBs, but proteinuria was more common in dogs with pMBs than in matched controls (odds ratio = 3.01, P = .005). Dogs with pMBs had a shorter median survival time than did matched controls (P = .011). CONCLUSIONS AND CLINICAL IMPORTANCE: Putative microbleeds occurred in 54 of 582 (9.3%) of dogs undergoing brain MRI, but may not be a normal consequence of aging. They were associated with shorter survival time and proteinuria in the study population.