C-reactive protein concentration has limited value in the diagnosis of meningoencephalitis of unknown origin in dogs

OBJECTIVES

To evaluate blood and cerebrospinal fluid (CSF) concentrations of C-reactive protein (CRP) in dogs with meningoencephalitis of unknown origin (MUO); to evaluate whether blood CRP concentration is associated with epidemiological, clinicopathologic, and MRI findings; and to investigate blood CRP predictive power in survival.

ANIMALS

30 client-owned dogs with MUO, 15 client-owned dogs with steroid-responsive meningitis arteritis (SRMA; positive control group), and 15 healthy dogs (negative control group).

METHODS

Blood CRP concentration was measured in each group, while it was performed in CSF only in the MUO and SRMA groups. The analysis of epidemiological data included breed, age, sex, duration of clinical signs, and history of seizures. Blinded analysis of MRI was performed based on a classification grid, and traditional CSF analysis parameters were assessed. The predictive power of blood CRP concentration regarding survival at 6 months was investigated.

RESULTS

Of the 30 dogs with MUO, 9 (30%) had an increased CRP concentration in blood, and 3 (10%) showed a measurable CRP in CSF. Median blood CRP concentration in dogs with MUO was 0.1 mg/L (range, 0.1 to 102 mg/L), which was not statistically different from the healthy dog group but significantly lower than the SRMA control group. Only the duration of clinical signs was positively associated with an increased blood CRP level. Blood CRP concentration was not associated with survival at 6 months.

CLINICAL RELEVANCE

Blood CRP concentration is of limited value for the diagnosis and prognosis of dogs with MUO. Chronicity of the disease may be associated with an increased concentration of blood CRP.

Borna disease in an adult free-ranging Eurasian beaver (Castor fiber albicus)

Borna disease (BD) associated with a peracute bacterial septicaemia with Escherichia coli was diagnosed in an adult female, naturally infected, free-ranging Eurasian beaver of the subspecies Castor fiber albicus, clinically characterized by weight loss, depression, weakness and gurgled peristaltic sounds. The beaver was euthanized humanely. Necropsy and light microscopy revealed a non-purulent meningoencephalitis with typical mononuclear perivascular cuffs and parenchymal infiltrates. The diagnosis of BD was confirmed by detection of viral antigen and RNA by immunohistochemistry and reverse transcription-polymerase chain reaction (RT-PCR). The PCR product was sequenced and cluster analysis revealed a close relationship between endemic clusters in Saxony-Anhalt. This is the first report of naturally occurring BD in a free-ranging Eurasian beaver.

An early clinical phenotype of necrotizing meningoencephalitis in the Pug reveals similarities to multiple sclerosis in humans

Necrotizing meningoencephalitis (NME) is a fatal neuroinflammatory disease that previously carried a uniformly grave prognosis. Our recent identification of a novel early form of NME in Pugs suggests that disease onset and progression are likely more insidious than previously recognized and provides new hope that early therapeutic intervention may halt disease progression and ultimately prevent or cure NME. This novel perspective also sheds new light on the clinical similarities to multiple sclerosis (MS) in humans and provides a rationale for cross-species translation. The history of recent scientific discoveries in NME and new parallels between MS and NME will be reviewed.

Borna disease virus 1 infection in alpacas: Comparison of pathological lesions and viral distribution to other dead-end hosts

Borna disease is a progressive meningoencephalitis caused by spillover of the Borna disease virus 1 (BoDV-1) to horses and sheep and has gained attention due to its zoonotic potential. New World camelids are also highly susceptible to the disease; however, a comprehensive description of the pathological lesions and viral distribution is lacking for these hosts. Here, the authors describe the distribution and severity of inflammatory lesions in alpacas (n = 6) naturally affected by this disease in comparison to horses (n = 8) as known spillover hosts. In addition, the tissue and cellular distribution of the BoDV-1 was determined via immunohistochemistry and immunofluorescence. A predominant lymphocytic meningoencephalitis was diagnosed in all animals with differences regarding the severity of lesions. Alpacas and horses with a shorter disease duration showed more prominent lesions in the cerebrum and at the transition of the nervous to the glandular part of the pituitary gland, as compared to animals with longer disease progression. In both species, viral antigen was almost exclusively restricted to cells of the central and peripheral nervous systems, with the notable exception of virus-infected glandular cells of the Pars intermedia of the pituitary gland. Alpacas likely represent dead-end hosts similar to horses and other spillover hosts of BoDV-1.

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.

Investigation of side effects to treatment and cause of death in 63 Scandinavian dogs suffering from meningoencephalitis of unknown origin: a retrospective study

BACKGROUND

Meningoencephalitis of unknown origin is a common cause of severe neurological disease in dogs. The term covers a heterogeneous group of noninfectious inflammatory diseases, with immune dysregulation widely accepted as the underlying disease mechanism. Current treatment consists of immunosuppression, with corticosteroids being the mainstay of virtually all treatment regimens. However, side effects of corticosteroids can be severe, and might be the cause of death in some patients. This retrospective, multi-centric study aimed at describing a population of Scandinavian dogs with meningoencephalitis of unknown origin in regards to reported side effects and cause of death, and to highlight possible differences in survival, when comparing corticosteroid monotherapy with other treatment regimens.

RESULTS

Within the 5-year study period, 63 dogs were included. Of these, 35 (49.3%) died or were euthanized during the study period. Median survival time from time of diagnosis based on Kaplan-Meier curves for the overall population was 714 days (equivalent to around 25 months, range 0-1678 days). There was no statistically significant difference (P = 0.31) in survival between dogs treated with corticosteroid monotherapy (n = 26, median survival time 716 days, equivalent to around 25 months, range 5-911 days), dogs receiving a combination of corticosteroids and ciclosporin (n = 15, median survival time 916 days, equivalent to around 31 months, range 35-1678 days), and dogs receiving corticosteroids combined with either cytosine arabinoside, leflunomide, or a combination of 2 or more add-on drugs (n = 13, median survival time 1186 days, equivalent to around 40 months, range 121-1640 days). Side effects were registered for 47/63 dogs. Polyphagia (n = 37/47), polyuria/polydipsia (n = 37/47), diarrhea (n = 29/47) and lethargy (n = 28/47) were most frequently reported. The most common cause for euthanasia was relapse (n = 15/35, 42.9%), followed by insufficient or lack of treatment response (n = 9, 25.7%). Side effects were the direct cause of euthanasia in 2/35 dogs (5.7%).

CONCLUSIONS

A large proportion of dogs in the overall population were euthanized due to relapse, emphasizing a need for treatment regimens aimed at specifically preventing relapse for an improved long-term survival. Side effects in dogs receiving corticosteroid monotherapy were rarely a direct cause of death, but were reported for all dogs. No statistically significant difference in survival was found when corticosteroid monotherapy was compared to other treatment regimens.

Application of metagenomics for diagnosis of broilers displaying neurological symptoms

BACKGROUND

Thirty-two-day-old broiler chickens at a farm located in northwestern South Korea displayed adverse neurological symptoms including limping, lying down, and head shaking. Approximately 2.1% of chickens died or were culled due to severe symptoms. Five carcasses were submitted to the Avian Disease Division of the Animal and Plant Quarantine Agency (APQA) for disease diagnosis.

RESULTS

Broilers displayed severe pericarditis and perihepatitis associated with gross lesions. Broilers also displayed microscopic lesions in the cerebrum and in the granular layer of the cerebellum, which were associated with multifocal perivascular cuffing and purulent necrosis in the cerebrum, and severe meningitis with heterophil and lymphocyte infiltration. Staphylococcus spp. were identified in the liver and heart using bacteriological culture. PCR/RT-PCR assays revealed that broilers were negative for avian Clostridium botulinum, Newcastle disease virus, and avian encephalomyelitis virus. Bacterial and viral metagenomic analysis of brain sample further revealed the presence of Pseudomonas spp. and Marek's disease virus, which are known etiological agents of chicken meningoencephalitis.

CONCLUSIONS

This study reports a diagnostic analysis of gross and histopathological lesions from 32-day-old broilers displaying unique neurological symptoms that revealed the presence of the several neurological diseases including meningoencephalitis. The causative agents associated with meningoencephalitis of broilers that had not been identified by routine diagnostic methods could be diagnosed by metagenomics, which proves the usefulness of metagenomics as a diagnostic tool for unknown neurological diseases in broilers.

Shared and unique antibody and B cell profiles in HIV-positive and HIV-negative individuals with cryptococcal meningoencephalitis

Host non-T cell markers to aid in the diagnosis of cryptococcal meningoencephalitis (CM) have not been identified. In this case-control study, we characterized antibody and B cell profiles in HIV-negative and HIV-positive Vietnamese individuals of the Kinh ethnicity recently diagnosed with CM and controls. The study included 60 HIV-negative with no known immunocompromising condition and 60 HIV-positive individuals, with 30 CM cases and 30 controls in each group. Participants were matched by age, sex, HIV serostatus, and CD4 count in the HIV-positive group. Plasma immunoglobulin (Ig) levels, including IgG1, IgG2, IgM, and IgA, Cryptococcus spp. glucuronoxylomannan (GXM)- and laminarin (branched ${\rm{\beta }}$-[1-3]-glucan)-binding IgG, IgM, IgA levels, and peripheral blood B cell subsets were measured. Logistic regression, principal component, and mediation analyses were conducted to assess associations between antibody, B cell levels, and CM. The results showed that GXM-IgG levels were higher and IgG1 and IgG2 were lower in CM cases than controls, regardless of HIV status. In HIV-negative individuals, IgG2 mediated an inverse association between CD19+CD27+CD43+CD5- (B-1b-like) cells and CM. In HIV-positive individuals, lower levels of IgA, laminarin-IgA, and CD19+CD27+IgM+IgD- (IgM+ memory B) cells were each associated with CM. The shared and distinct antibody and B cell profiles identified in HIV-negative and HIV-positive CM cases may inform the identification of non-T-cell markers of CM risk or unsuspected disease, particularly in HIV-negative individuals.

Meningoencephalomyelitis associated with foreign plant material in a dog: case report and brief literature review

Neurologic disease associated with migration of plant material is reported infrequently in dogs. Here we describe meningoencephalomyelitis associated with foreign plant material in a 2-y-old castrated male West Highland White Terrier dog with acute neck pain. Magnetic resonance imaging revealed spinal meningeal contrast enhancement. Although clinical signs improved after treatment with steroids, the dog was readmitted for further evaluation 3-mo later and was euthanized after generalized epileptic seizures. Autopsy findings consisted of coalescing, pus-filled, neuroparenchymal cavitations surrounded by hemorrhage in the left caudal colliculus and rostral left cerebellar hemisphere. Histologically, lesions consisted of necrosis and suppuration, which surrounded a 1 × 2-mm foreign body morphologically consistent with plant material and clusters of gram-positive bacterial cocci. Affected areas were surrounded by reactive astrocytes, fibrous connective tissue, and mixed inflammatory infiltrates. Areas of hemorrhage and infiltration by neutrophils and foamy macrophages with fibrinoid change of small capillaries were observed in the adjacent neuroparenchyma. The inflammation extended to the perivascular spaces in the leptomeninges (mesencephalon, cerebellum, and brainstem, and spinal cord) and spinal central canal. Anaerobic bacterial culture of frozen samples of cerebellum yielded heavy growth of Bacteroides pyogenes.

A Preliminary Study of Pharmacokinetics and Pharmacodynamics of Oral Fingolimod in Dogs

BACKGROUND/AIM

Fingolimod is a sphingosine-1-phosphate receptor modulator that prevents lymphocytes egress from lymphoid organs. It has been used as a disease-modifying drug for human multiple sclerosis and has shown better therapeutic effects than other conventional therapies. Therefore, this study was performed to obtain preclinical data of fingolimod in dogs.

MATERIALS AND METHODS

Nine laboratory Beagle dogs were used and randomized into three groups for pharmacokinetics (PK) and pharmacodynamics (PD). The dogs were administered once with a low-dose (0.01 mg/kg, n=3), medium-dose (0.05 mg/kg, n=3), and high-dose (0.1 mg/kg, n=3) of fingolimod, orally. Samples were collected serially at predetermined time points, and whole blood fingolimod concentrations were measured using high-performance liquid chromatography-mass spectrometry. Differential counts of leukocytes over time were determined to identify immune cells' response to fingolimod.

RESULTS

Regarding PK, the concentration of fingolimod in the blood increased in a dose-dependent manner, but it was not proportional. Regarding PD, the number of lymphocytes significantly decreased compared to baseline in all dose groups (low-dose, p=0.0002; medium-dose, p<0.0001; high-dose, p=0.0012). Eosinophils were significantly reduced in low- (p=0.0006) and medium- (p=0.0006) doses, and neutrophils were also significantly reduced in medium-(p=0.0345) and high- (p=0.0016) doses.

CONCLUSION

This study provides the basis for future clinical applications of fingolimod in dogs with immune-mediated diseases, such as meningoencephalitis of unknown etiology.

Immunohistochemical evaluation of fibrin/fibrinogen, d-dimers, and intravascular thrombosis in brains of dogs with meningoencephalitis of unknown origin

Granulomatous meningoencephalitis (GME) and necrotizing encephalitides (NE) are the most common immune-mediated inflammatory diseases of the central nervous system in dogs. Activation of the fibrinolytic system in multiple sclerosis, a similar immune-mediated disease affecting the central nervous system in humans, seems to be related to disease progression. The aim of this study was to identify fibrin/fibrinogen and D-dimer deposition, as well as presence of intravascular thrombosis (IVT) in brains of dogs with a diagnosis of GME or NE. Immunohistochemical studies using antibodies against fibrin/fibrinogen and D-dimers were performed. Statistical analyses were performed to determine whether there were differences in the presence and location of fibrin/fibrinogen, D-dimers deposits, and IVT between GME and NE. Samples from sixty-four dogs were included in the study: 32 with a diagnosis of GME and 32 with a diagnosis of NE. Fibrin/fibrinogen depositions were detected in all samples and d-dimers were detected in 43/64 samples. IVT was present in 29/64 samples, with a significantly higher score in samples from dogs with NE than in samples from dogs with GME (P = 0.001). These data support hemostatic system activation in both diseases, especially NE. This finding might be related to the origin of the necrotic lesions seen in NE, which could represent chronic ischemic lesions. Further studies are needed to investigate the association between vascular lesions and the histopathological differences between GME and NE and the hemostatic system as a potential therapeutic target.

Phlebovirus detection on phlebotomine sandflies in Lampedusa Island (Italy)

Phleboviruses are common human pathogens diffused on the Mediterranean area whose infection can cause the typical prodromal symptom of a mild three‑days fever. In particular, Toscana Virus (TOSV) has a great concern since its capacity to provoke central nervous system disorders like meningoencephalitis. Furthermore, as the phlebotomine arthropod vectors represent the main carrier for pathogens of the genus Leishmania as well, the purpose of the study was to investigate the presence of TOSV in Lampedusa, Italy previously reported for leishmaniosis infection cases. The survey was carried out through an initial sampling phase of sand flies, by means of CDC light traps, and a second step of molecular analyses. The genomic S‑segment of TOSV was targeted. The positive samples were sequenced and compared with those available in GenBank™ using Basic Local Alignments Tool (BLAST) analyses. The study revealed for the first time the presence of TOSV in Lampedusa, Italy. The entomological studies directed on vectors are currently widely used in sand fly surveillance, and new data on TOSV are of public health concern.

Meningoencephalitis caused by concurrent infection with canine distemper virus and a unique Sarcocystis sp. in a gray fox

A deceased 9-wk-old male gray fox (Urocyon cinereoargenteus) with a history of decreased ambulation and diarrhea was submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory. No significant gross findings were evident on postmortem examination. Histologically, the cerebrum and brainstem had mild necrotizing meningoencephalitis with protozoal schizonts and merozoites. Additionally, glial cells contained intracytoplasmic and intranuclear viral inclusion bodies. Sections of the cerebrum were positive for canine distemper virus (CDV) and negative for Sarcocystis neurona on immunohistochemistry. Bayesian analysis revealed that this Sarcocystis sp. clustered most closely with a clade of unnamed Sarcocystis sp. found in viperid snakes, with a posterior probability of 99%. CDV likely played a significant role in the expression of clinical sarcocystosis in this gray fox.

Rustrela Virus as Putative Cause of Nonsuppurative Meningoencephalitis in Lions

Retrospective investigation of archived tissue samples from 3 lions displaying nonsuppurative meningoencephalitis and vasculitis led to the detection of rustrela virus (RusV). We confirmed RusV antigen and RNA in cortical neurons, axons, astrocytes and Purkinje cells by reverse transcription quantitative PCR, immunohistochemistry, and in situ hybridization.

Assessment of oligoclonal bands in cerebrospinal fluid and serum of dogs with meningoencephalitis of unknown origin

BACKGROUND

Meningoencephalitis of unknown origin (MUO) is an inflammatory disease of the canine central nervous system (CNS) that shares several features with multiple sclerosis (MS) in humans. In approximately 95% of MS patients, ≥ two immunoglobulin G (IgG) oligoclonal bands (OCBs) are detectable exclusively in the cerebrospinal fluid (CSF).

HYPOTHESIS/OBJECTIVES

To investigate OCBs in CSF and serum in dogs affected by MUO, intervertebral disc disease (IVDD), idiopathic epilepsy (IE), intracranial neoplasia (IN), steroid-responsive meningitis-arteritis (SRMA), and diseases outside the CNS. We hypothesize that the highest prevalence of CSF-specific OCBs (≥ two OCBs uniquely in the CSF) would be found in dogs affected by MUO.

ANIMALS

Client-owned dogs (n = 121) presented to the neurology service due to neurological deficits.

METHODS

Prospective study. Measurement of IgG concentration in CSF and serum via a canine IgG ELISA kit. OCB detection via isoelectric focusing (IEF) and immunoblot.

RESULTS

Presence of CSF-specific OCBs was significantly higher in dogs with MUO (57%) compared to 22% in IN, 6% in IE, 15% in SRMA, 13% in IVDD, and 0% in the non-CNS group (p < .001). Dogs with MUO were 9.9 times more likely to show CSF-specific OCBs than all other diseases together (95% confidence interval, 3.7-26.4; p < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

MUO showed the highest prevalence of CSF-specific OCBs, indicating an inflammatory B cell response. Future studies are needed to evaluate the prevalence in the specific MUO subtypes and a possible similarity with human MS.

A potential early clinical phenotype of necrotizing meningoencephalitis in genetically at-risk pug dogs

BACKGROUND

Necrotizing meningoencephalitis (NME) in the pug dogs is a fatal neuroinflammatory disease associated with rapid progression and poor response to conventional immunosuppressive therapy. Diagnosis is typically made after severe neurological abnormalities have manifested.

HYPOTHESIS/OBJECTIVE

Pug dogs at genetic risk for NME might manifest neurological abnormalities before developing pathognomonic clinical signs of NME.

ANIMALS

Thirty-six pug dogs less than 4 years of age asymptomatic for NME.

METHODS

Prospective observational cohort study with germline genome-wide genotyping. Neurological examinations were performed 4 weeks apart to document reproducible findings of central nervous system disease. Magnetic resonance imaging, cerebrospinal fluid analysis, and testing for infectious diseases were performed in all pugs with reproducible abnormalities detected on neurological examination.

RESULTS

The overall risk allele frequency in this cohort was 40%; 5 (14%) dogs were high risk, 19 (53%) dogs were medium risk, and 12 (33%) dogs were low genetic risk for NME. Reproducible abnormalities detected on neurological examination were identified in 8/24 (33%) genetically at-risk dogs and 0/12 (0%) low risk dogs. Clinical abnormalities included multifocal spinal pain in 8/8, reduced menace response in 5/8, and lateralizing postural reaction deficits in 5/8 pugs. There was a strong association between genotype risk and the presence of this clinical phenotype (P = .03).

CONCLUSIONS AND CLINICAL IMPORTANCE

Our findings suggest the presence of a novel early clinical phenotype of NME in apparently asymptomatic genetically at-risk pugs which might be used to plan early diagnostic and therapeutic clinical trials.

Eosinophilic meningoencephalitis caused by rat lungworm (Angiostrongylus cantonensis) migration in a white-eared opossum (Didelphis albiventris) with concurrent distemper virus in southern Brazil

Angiostrongylus cantonensis is a worldwide zoonotic parasite that causes eosinophilic meningoencephalitis in many species of animals including humans. This report describes neuro-angiostrongylosis in a white-eared opossum that showed nervous clinical signs such as circling and depression. At necropsy, no relevant macroscopic lesions were observed. Histologically, eosinophilic meningoencephalitis was associated with multiple sections of nematodes and many intracytoplasmic eosinophilic inclusion bodies within gastric parietal cells. Immunohistochemistry was strongly positive for canine distemper virus in the stomach but there was no immunolabeling in the brain. This study describes a fatal case of eosinophilic meningoencephalitis by A. cantonensis with canine distemper virus concurrent infection in a white-eared opossum in southern Brazil, with histological characterization and molecular confirmation of the parasitism.

Neuroinflammatory diseases of the central nervous system of dogs: A retrospective study of 207 cases (2008-2019)

In this study we describe 207 cases of neuroinflammatory diseases of the central nervous system (CNS) in dogs autopsied at the Athens Veterinary Diagnostic Laboratory (University of Georgia, United States) from 2008 to 2019. Idiopathic and infectious diseases were diagnosed in 111 cases (53.6%) and 96 cases (46.4%), respectively. Idiopathic diseases consisted of granulomatous meningoencephalomyelitis (n = 42; 37.8% of idiopathic cases), nonspecific lymphoplasmacytic meningoencephalomyelitis (n = 39; 35.1%), necrotizing meningoencephalomyelitis (n = 22; 19.8%), presumed steroid-responsive meningitis-arteritis (n = 6; 5.4%), and necrotizing leukoencephalitis (n = 2; 1.8%). Infectious diseases consisted of bacterial infections (n = 49; 51% of infectious cases), viral infections (n = 39; 40.6%), fungal infections (n = 5; 5.2%), and parasitic infections (n = 3; 3.1%). Our study provides an overview of the most frequent neuroinflammatory diseases of the CNS of dogs in our diagnostic routine; indicates that a comprehensive diagnostic approach, including a thorough evaluation of the pathology findings and ancillary laboratory testing results, is important for an adequate diagnosis of neurologic diseases in dogs; and underscores the problems associated with the variability in tissue sample collection methods among cases. The great number of nonspecific lymphoplasmacytic meningoencephalitis also highlights the need for development of molecular laboratory tests to identify potential infectious agents in these cases.

Magnetic resonance imaging, clinicopathologic findings, and clinical progression of a puppy with confirmed Eastern equine encephalitis virus

A 5-month-old puppy was evaluated for rapidly progressive neurologic signs and pyrexia. Magnetic resonance imaging showed multifocal meningoencephalitis with transtentorial and foramen magnum herniation. A cerebrospinal fluid tap revealed highly cellular fluid, and the puppy was euthanized. Histopathology showed lymphoplasmacytic and neutrophilic meningoencephalitis. Viral polymerase chain reaction testing for Eastern equine encephalitis was positive. Rapid progression of neurologic signs and respiratory arrest necessitated mechanical ventilation. Severe hypernatremia, most consistent with central diabetes insipidus, developed. Key clinical message: Transtentorial and foramen magnum herniation and high cerebrospinal fluid cell counts may be indicators of poor prognosis. Brain death, respiratory arrest, and central diabetes insipidus may also ensue with Eastern equine encephalitis infection.

Neurofilament light chain as a biomarker of meningoencephalitis of unknown etiology in dogs

BACKGROUND

Neurofilament light chain (NfL) is a neuron-specific cytoskeletal protein expressed in axons. Damaged axons of the central nervous system release NfLs into the cerebrospinal fluid (CSF) and the blood. In humans with neurologic diseases, NfL is used as a biomarker.

OBJECTIVES

To identify the potential of NfL as a supportive tool for the diagnosis, prognosis, and monitoring of meningoencephalitis of unknown etiology (MUE) in dogs.

ANIMALS

Twenty-six client-owned healthy dogs, 10 normal Beagle dogs, and 38 client-owned MUE dogs.

METHODS

Cohort study. The concentrations of NfL in serum and CSF were measured using single-molecule array technology.

RESULTS

Median NfL concentration was significantly higher in MUE dogs (serum, 125 pg/mL; CSF, 14 700 pg/mL) than in healthy dogs (serum, 11.8 pg/mL, P < .0001; CSF, 1410 pg/mL, P = .0002). The areas under the receiver operating characteristic curves of serum and CSF NfL concentrations were 0.99 and 0.95, respectively. The cut-off values were 41.5 pg/mL (serum) and 4005 pg/mL (CSF) for differentiating between healthy and MUE dogs, with sensitivities of 89.19% and 90%, respectively, and specificities of 96.97% and 100%, respectively. The NfL concentration showed a significant decrease (pretreatment, 122 pg/mL; posttreatment, 36.6 pg/mL; P = .02) in the good treatment-response group and a significant increase (pretreatment, 292.5 pg/mL; posttreatment, 1880 pg/mL, P = .03) in the poor treatment-response group.

CONCLUSIONS AND CLINICAL IMPORTANCE

Neurofilament light chain is a potential biomarker for diagnosing MUE and evaluating response to treatment.

Meningoencephalitis in a common minke whale Balaenoptera acutorostrata associated with Brucella pinnipedialis and gamma-herpesvirus infection

Fatal marine Brucella infections with histologic lesions specific to the central nervous system (CNS), known as neurobrucellosis, have been described in 5 species of odontocete cetaceans in the UK: striped dolphins Stenella coeruleoalba, Atlantic white-sided dolphins Lagenorhynchus acutus, short-beaked common dolphins Delphinus delphis, long-finned pilot whale Globicephala melas and Sowerby's beaked whale Mesoplodon bidens. To date, these CNS lesions have only been associated with Brucella ceti ST26 and not with B. pinnipedialis, which is rarely isolated from cetaceans and, although commonly found in various seal species, has never been associated with any pathology. This paper describes the first report of neurobrucellosis in a common minke whale Balaenoptera acutorostrata which was associated with the isolation of Brucella pinnipedialis ST24 and co-infection with Balaenoptera acutorostrata gamma-herpesvirus 2. This is the first report of neurobrucellosis in any species of mysticete and the first report of Brucella pinnipedialis in association with any pathology in any species of marine mammal, which may be due to co-infection with a herpesvirus, as these are known to be associated with immunosuppression.

[Diagnostics in epilepsy - potential of magnetic resonance imaging]

Epilepsy is a common neurologic disease frequently encountered by small animal practitioners. The disease comprises a multiplicity of clinical presentations and etiologies and often necessitates a comprehensive as well as cost-intensive diagnostic workup. This is mandatory in order to be able to diagnose or exclude a metabolic cause of the seizures and to distinguish between idiopathic and structural epilepsy. The examination by means of magnetic resonance imaging (MRI) represents a central component of the diagnostic workup, which in turn has essential effects on treatment and prognosis. In order to achieve standardized examination and comparable results, it is of utmost importance to use defined MRI protocols. Accordingly, communication and interaction between clinical institutions may be facilitated and as of yet undetected structural changes might be recorded in future MRI techniques. This review article sets particularly emphasis on the definition and classification of epilepsy as well as its diagnostic imaging procedures and refers to statistics and specialists' recommendations for the diagnostic workup in dogs.

Evaluation of cell-based and tissue-based immunofluorescent assays for detection of glial fibrillary acidic protein autoantibodies in the cerebrospinal fluid of dogs with meningoencephalitis of unknown origin and other central nervous system disorders

OBJECTIVE

To evaluate whether cell-based and tissue-based immunofluorescent assays (IFAs) run in parallel could be used to detect glial fibrillary acidic protein (GFAP) autoantibodies in the CSF of dogs with meningoencephalitis of unknown origin (MUO) and other CNS disorders.

ANIMALS

15 CSF samples obtained from dogs with presumed MUO (n = 5), CNS disease other than MUO (5), and idiopathic epilepsy (5).

PROCEDURES

All CSF samples underwent parallel analysis with a cell-based IFA that targeted the α isoform of human GFAP and a tissue-based IFA that involved mouse brain cryosections. Descriptive data were generated.

RESULTS

Only 1 CSF sample yielded mildly positive results on the cell-based IFA; that sample was from 1 of the dogs with presumed MUO. The remaining 14 CSF samples tested negative on the cell-based IFA. All 15 CSF samples yielded negative results on the tissue-based IFA.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that concurrent use of a cell-based IFA designed to target the human GFAP-α isoform and a tissue-based IFA that involved mouse tissue cryosections was inadequate for detection of GFAP autoantibodies in canine CSF samples. Given that GFAP autoantibodies were likely present in the CSF samples analyzed, these findings suggested that epitopes differ substantially between canine and human GFAP and that canine GFAP autoantibody does not bind to mouse GFAP. Without a positive control, absence of GFAP autoantibody in this cohort cannot be ruled out. Further research is necessary to develop a noninvasive and sensitive method for diagnosis of MUO in dogs.

Magnetic resonance imaging in dogs with neuroangiostrongyliasis (rat lungworm disease)

The magnetic resonance imaging (MRI) appearance of the brain and spinal cord in humans with neuroangiostrongyliasis (NA) due to Angiostrongylus cantonensis infection has been well reported. Equivalent studies in animals are lacking. This case series describes clinical and MRI findings in 11 dogs with presumptively or definitively diagnosed NA. MRI of the brain and/or spinal cord was performed using high-field (1.5 T) or low-field (0.25 T) scanners using various combinations of transverse, sagittal, dorsal and three-dimensional (3D) T1-weighted (T1W), transverse, sagittal and dorsal T2-weighted (T2W), T2W fluid-attenuated inversion recovery (FLAIR) and T2*-weighted (T2*W) gradient echo (GRE), dorsal T2W short tau inversion recovery (STIR) and post-gadolinium transverse, sagittal, dorsal and 3D T1W and transverse T2W FLAIR sequences. In 4/6 cases where the brain was imaged, changes consistent with diffuse meningoencephalitis were observed. Evidence of meningeal involvement was evident even when not clinically apparent. The spinal cord was imaged in 9 dogs, with evidence of meningitis and myelitis detected in regions consistent with the observed neuroanatomical localization. Pathognomonic changes of neural larva migrans, as described in some human patients with NA, were not detected. NA should be considered in the differential diagnosis of dogs with MRI evidence of focal or diffuse meningitis, myelitis and/or encephalitis, especially in areas where A. cantonensis is endemic. If not precluded by imaging findings suggestive of brain herniation, cerebrospinal fluid (CSF) collection for cytology, fluid analysis, real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) testing should be considered mandatory in such cases after the MRI studies.

Cytosine arabinoside constant rate infusion without subsequent subcutaneous injections for the treatment of dogs with meningoencephalomyelitis of unknown origin

BACKGROUND

The administration of cytosine arabinoside (CA) by continuous rate infusion (CRI) at the time of diagnosis has been shown to improve the 3-month survival of dogs diagnosed with meningoencephalomyelitis of unknown origin (MUO), compared to subcutaneous administration. The benefit of administering subsequent sequential CA subcutaneous injections is unknown. This study compares the outcomes of a CA CRI protocol with (CRI+subcutaneous group) or without (CRI group) follow-up CA subcutaneous injections; both groups received adjunctive prednisolone.

METHODS

Forty-two dogs diagnosed with MUO were recruited (CRI group) and compared with 41 historical control dogs (CRI+subcutaneous group) in a prospective, controlled clinical trial with 36 months of follow-up.

RESULTS

Success rates were respectively 64.3 per cent and 65 per cent in the CRI and the CRI+subcutaneous groups at 40 weeks following diagnosis, and 32.5 per cent and 35.9 per cent at 36 months following diagnosis. The median time to relapse was 299 and 285 days for the CRI and the CRI+subcutaneous groups, respectively. No statistically significant difference was found (P≥0.05).

CONCLUSION

No clear benefit was identified in the administration of subsequent sequential CA subcutaneous injections after the first administration of CA by CRI for the treatment of dogs diagnosed with MUO.

Case-control study of risk factors for granulomatous meningoencephalomyelitis in dogs

OBJECTIVE

To identify environmental and other variables associated with a diagnosis of granulomatous meningoencephalomyelitis (GME) in dogs.

DESIGN

Case-control study.

ANIMALS

31 dogs that received a histologic diagnosis of GME (case dogs) from January 2003 to January 2014 and 91 age- and breed-matched dogs.

PROCEDURES

Data were obtained from each dog's medical records regarding home address, signalment, body weight, body condition score (BCS), vaccination history, and date of diagnosis (case dogs) or visit (control dogs). Home address data were used to determine the human population density in each dog's geographic region. Seasonal distributions of GME diagnoses in the case group were evaluated for differences. Case and control dogs were compared with respect to the remaining variables.

RESULTS

For case dogs, no significant difference was identified among seasons in the distribution of GME diagnoses; however, such diagnoses were more common in the spring than in other seasons. No significant differences were identified between case and control dogs in age, body weight, BCS, human population density, season of diagnosis or visit, or time of last vaccination. Although females appeared more likely than males to have a GME diagnosis, this association was not significant and did not change when BCS, time since last vaccination, or human population density was considered.

CONCLUSIONS AND CLINICAL RELEVANCE

None of the evaluated factors, including investigated environmental triggers, were associated with a GME diagnosis in the dogs of this study. Additional research is warranted involving dogs from a broader geographic area.

Cladophialophora encephalitis in an alpaca

A 4-year-old Huacaya hembra was evaluated for acute neurologic signs including recumbency and a left head tilt. Cranial nerve examination revealed a left ear droop, muzzle deviation to the right, mydriasis of the left eye, an absent menace response, bilateral absent pupillary light reflex when light was directed into the left eye, and bilateral horizontal nystagmus with fast phase to the right. Multifocal intracranial lesions were suspected. Computed tomography revealed an intracranial mass. Postmortem examination, histopathology, and sequencing of a polymerase chain reaction product confirmed a diagnosis of phaeohyphomycotic meningoencephalitis caused by Cladophialophora bantiana. Key clinical message: Advanced diagnostic imaging (computed tomography) was useful in achieving a diagnosis of an intracranial mass in an alpaca with acute neurological signs, later confirmed to be central nervous system (CNS) phaeohyphomycosis. Although uncommon, intracranial fungal infection should be considered as a differential diagnosis in camelid patients exhibiting CNS signs, particularly if they do not respond to initial antimicrobial and anthelmintic therapy.

First Case of Idiopathic Eosinophilic Meningoencephalitis in a Sheep

A 1.5-year-old ewe was presented with neurological signs that had been observed from about 2 days prior to death. There had been no clinical response to anti-inflammatory and antibiotic treatment. Histopathological examination of the brain revealed a severe and widespread eosinophilic meningoencephalomyelitis of unknown aetiology. Defining histological features included diffuse angiocentric eosinophilic infiltrates in the neuroparenchyma and meninges, neuronal necrosis, astrocytosis, neuropil vacuolation and occasional glial scars. Differential diagnostics for eosinophilic meningoencephalitis were taken into account and investigated by means of special stains, immunohistochemistry, bacteriology and polymerase chain reaction. No pathological changes or ancillary tests were supportive or revealed a specific aetiology for the condition and therefore it was considered idiopathic. Idiopathic meningoencephalitis is a rare disease, mainly described in man and rarely in dogs, with no apparent aetiological cause or potential breed predisposition. To our knowledge this is the first case of idiopathic eosinophilic meningoencephalitis in a sheep and provides a histopathological guideline for prospective comparative pathology studies.

Neurological symptoms and mortality associated with Streptococcus gallolyticus subsp. pasteurianus in calves

Suppurative meningitis-meningoencephalitis (M-ME) is a sporadic disease in neonatal ungulates and only a few studies have reported the involvement of Streptococcus bovis/Streptococcus equinus complex (SBSEC) members in bovine neonatal M-ME. The SBSEC taxonomy was recent revised and previous biotype II/2 was reclassified as S. gallolyticus subsp. pasteurianus (SGP). The aim of this study was to describe a case of fatal neonatal neurological syndrome associated with SGP in calves. Ten calves were monitored because of neurological hyperacute symptoms associate with bilateral hypopyon and death. They were not fed with maternal colostrum; two of them died and were subjected to bacteriological, histopathological and biomolecular analysis as well as antibiotic susceptibility test. Both animals presented lesions mostly concentrated to meninges and brain and had bilateral hypopyon. Nine strains isolated in purity from brain, ocular humors and colon were identified as S. bovis group by using the API Strep system and as S. gallolyticus by using the 16S rRNA sequence. Two of these strains where subjected to WGS analysis that confirmed the sub-species identification and the clonality of the two SGP strains. The strains were found resistant to OT, SXT, MTZ and EN and susceptible to AMP, AMC, KZ and CN. We hypothesized that the syndrome observed could be due to the lack of maternal colostrum feeding. A timely and precise diagnosis could have likely prevented the death of the calves and, since the zoonotic potential of SBSECs members is known, accurate and rapid identification is required.

Confirmation of Sarcocystis jamaicensis Sarcocysts in IFN-γ Gene Knockout Mice Orally Inoculated with Sporocysts from a Red-Tailed Hawk ( Buteo jamaicensis)

Here, we report confirmation of sarcocysts of Sarcocystis jamaicensis in an experimental intermediate host, IFN-γ gene knockout (KO) mice orally inoculated sporocysts from its natural definitive host, a red-tailed hawk ( Buteo jamaicensis) (RTH). A RTH submitted to the Carolina Raptor Center, Huntersville, North Carolina, was euthanized because it could not be rehabilitated and released. Fully sporulated sporocysts from intestinal scrapings of the RTH were orally fed to 2 laboratory-reared outbred Swiss Webster mice (SW; Mus musculus) and to 2 KO mice. The sporocysts were infective for KO mice but not to SW mice. Both SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in their tissues when euthanized on day 54 post-inoculation (PI). The KO mice developed neurological signs and were necropsied 38-54 days PI. Schizonts/merozoites were found in both KO mice euthanized and they were confined to the brain. The predominant lesion was meningoencephalitis. Microscopic sarcocysts were found in muscles of both KO mice. When viewed with light microscopy, the sarcocyst wall appeared thin (<1 μm thick) and smooth. Ultrastructural details of sarcocysts are described.

Neurologic Baylisascaris procyonis infection in a young dog

A 14-week-old female Boston terrier-cross dog with intermittent gastroenteritis and an eosinophilia developed progressive neurologic disease with ataxia progressing to uncontrolled paddling. Autopsy revealed Baylisascaris procyonis larvae in 4 of 7 brain sections, with severe eosinophilic meningoencephalitis. Diagnosis was confirmed with polymerase chain reaction (PCR) and DNA sequencing tests of fresh and paraffin-embedded brain in conjunction with the compatible histologic appearance.

Cerebral toxoplasmosis in a cat with feline leukemia and feline infectious peritonitis viral infections

A diarrheic young cat died after neurological involvement. Biochemistry pointed to feline infectious peritonitis (FIP). The final diagnosis was severe multifocal meningoencephalitis due to Toxoplasma gondii. The presence of the parasite in the brain was confirmed using immunohistochemical staining. Concomitant feline leukemia virus (FeLV) and FIP were possible contributors to the clinical, fatal outcome.

Canine amoebic meningoencephalitis due to Balamuthia mandrillaris

A 1-year-old Siberian Husky dog with acute-onset of seizures, recumbency, paddling, and muscular fasciculations was autopsied. A locally extensive hemorrhagic and malacic focus was noted in the right cerebral frontal cortex, and severe necrotizing and hemorrhagic, neutrophilic meningoencephalitis was diagnosed microscopically. Amoebic trophozoites and cysts were identified within the affected cerebral parenchyma and confirmed by indirect immunofluorescence assay and real-time PCR as Balamuthia mandrillaris. B. mandrillaris is found in soil and water and the infection has been reported in both immunocompromised and immunocompetent humans and rarely in the dog.

Comparison between cerebrospinal fluid and serum lactate concentrations in neurologic dogs with and without structural intracranial disease

The objectives of this study were to investigate the relationship between cerebrospinal fluid lactate and serum concentrations in dogs with clinical signs of central nervous system disease and to establish if cerebrospinal fluid lactate (CSF) concentrations are higher in dogs with structural intracranial disease (Group Pos-MRI) compared to dogs that have clinical signs of intracranial disease but no structural brain disease (Group Neg-MRI) based on magnetic resonance imaging (MRI) findings. Using a prospective study canine blood and cerebrospinal fluid were collected in 24 dogs with neurological signs after undergoing brain MRI. Dogs were divided in 2 groups. No significant difference between serum lactate (1.57 ± 0.9 mmol/L) and CSF lactate concentration (1.34 ± 0.3 mmol/L) was detected. There was a direct correlation between CSF and serum lactate concentration (R = 0.731; P = 0.01). No significant difference was found in CSF lactate concentration between the 2 groups of dogs (P = 0.13).

Locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a zebra shark

Scuticociliatosis, caused by ciliated protozoa in the subclass Scuticociliatia of the phylum Ciliophora, can cause fatal disease in teleost fish species. However, information on scuticociliatosis in elasmobranchs is still scarce. In this report, we describe a case of locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a 2 yr old captive zebra shark Stegostoma fasciatum. Granulocytic meningoencephalitis was observed through histological assessment. Inflammation was confined to the ventral aspect of the brain with a large number of ciliated protozoa, transforming into non-suppurative meningitis in the lateral aspect, and gradually vanished in the dorsal aspect. No histopathological and polymerase chain reaction (PCR) evidence of systemic dissemination of M. avidus was found. PCR targeting the gene coding the small-subunit ribosomal RNA (SSUrRNA) of M. avidus was performed on the brain, liver, and gill tissues, and only brain tissue yielded a positive result. The DNA sequences from amplicons of the protozoal SSUrRNA gene were completely matched to that of M. avidus. The distribution of protozoa in the current case was mainly located in the brain and suggests the possibility of a direct neural invasive pathway of M. avidus through the nasal cavity/ampullary system and/or a unique tissue tropism of M. avidus specific to the brain in zebra sharks. Further investigations on the pathogenesis of M. avidus in elasmobranchs, especially zebra sharks, are needed.

Integrated analysis neurimmiRs of tilapia (Oreochromis niloticus) involved in immune response to Streptococcus agalactiae, a pathogen causing meningoencephalitis in teleosts

MicroRNAs (miRNAs) are a class of noncoding RNA molecules and play important roles in a wide spectrum of biological processes, including in immune response. Recent years have witnessed considerable amount of research interest in studies on miRNA-mediated modulation gene function during neuroinflammation. Here, we evaluated Streptococcus agalactiae infected tilapia (Oreochromis niloticus) brain for the expression profile of miRNAs, potential functions and their correlation with genes involved in inflammatory pathways. A total of 1981 miRNAs were identified, including in 486 miRNAs which have homologues in the currently available databases and 1945 novel miRNAs. The expression levels of 547 miRNAs were significantly altered at 6 h-48 h post-bacterial infection, and these miRNAs were therefore classified as differentially expressed tilapia miRNAs. Real-time PCR were implemented for 14 miRNAs co-expressed in five samples, and agreement was confirmed between the high-throughput sequencing and real-time PCR data. For the 486 differentially expressed miRNAs target 41,820 genes. GO and KEGG enrichment analysis revealed that some target genes of miRNAs were grouped mainly into the categories of apoptotic, signal pathwayand immune response. This is the first report of comprehensive identification of teleost miRNAs being differentially regulated in brain in normal conditions relating to bacterial infection.

Sarcocystis sp.-Associated Meningoencephalitis in a Bald Eagle (Haliaeetus Leucocephalus)

Protozoal meningoencephalitis is uncommon in raptors. An adult female bald eagle ( Haliaeetus leucocephalus) was euthanized after several months of treatment for progressive neurologic signs. The predominant histologic lesion was lymphoplasmacytic and histiocytic meningoencephalitis involving the cerebrum and cerebellum. There was a marked segmental loss of granular cells and Purkinje cells, as well as segmental atrophy of the molecular layer in the cerebellum. Protozoal merozoites and schizonts were observed in the gray matter of the cerebellum. Ultrastructurally, the merozoites were classified as a species of Sarcocystis due to the lack of rhoptries. Immunohistochemistry of the agent revealed a positive reaction for Sarcocystis neurona, while sections were negative for Toxoplasma gondii and Neospora caninum. Sarcocystis sp. infection should be considered as a differential diagnosis in bald eagles with chronic neurologic disease.

Ventricular pneumocephalus, cervical subarachnoid pneumorrhachis, and meningoencephalitis in a dog following rhinotomy for chronic fungal rhinitis

CASE DESCRIPTION

A 5-year-old 35.8-kg (78.8-lb) neutered male Labrador Retriever was evaluated for chronic nasal discharge associated with a fungal infection. The dog had previously been prescribed antimicrobials and antifungal treatment, but owner compliance was lacking.

CLINICAL FINDINGS

Bilateral mucopurulent nasal discharge, mild ulceration of the left nasal commissure, and hyperkeratosis of the dorsal nasal planum were present. Computed tomography revealed destruction of the intranasal structures, focal lysis of the cribriform plate, and invasion of a soft-tissue mass into the frontal cortex. Rhinoscopy revealed a large pale mass in the caudal aspect of the right nasal passage; a biopsy sample was consistent with Aspergillus sp on histologic evaluation.

TREATMENT AND OUTCOME

Initial treatment included medical management with an antifungal agent. Approximately 3 months later, a large fungal granuloma in the right frontal sinus was removed and debridement was performed via dorsal rhinotomy. One month after surgery, the dog was evaluated for signs of cervical pain and altered mentation. An MRI and CSF analysis were performed; diagnoses of ventricular pneumocephalus, subarachnoid pneumorrhachis, and meningoencephalitis were made. Management included oxygen therapy and administration of antimicrobials, analgesics, and antifungal medications. On follow-up 9 months after initial evaluation, neurologic deficits were reportedly resolved, and the dog was doing well.

CONCLUSIONS AND CLINICAL RELEVANCE

This report emphasizes the importance of prompt, appropriate treatment of fungal rhinitis in dogs. Although rare, pneumocephalus and pneumorrhachis should be included as differential diagnoses for neurologic signs following treatment for this condition. In this dog, the complications were not considered severe and improved over time with supportive care.

Meningoencephalitis Tuberculosa in a Holstein Cow

The gross and histopathologic lesions of meningoencephalitis tuberculosa in a 4-year-old Holstein cow showing clinical signs compatible with bovine spongiform encephalopathy are described in this report. Grossly, numerous gray to yellow, firm and caseous nodules were seen on the ventral surfaces of the brain and in the lateral and fourth ventricles. Histopathologically, foci of caseation and dystrophic mineralization were surrounded by multinucleated giant cells, epitheloid macrophages, plasma cells, lymphocytes and fibrous proliferation. Ziehl-Neelsen stains of the lesions revealed masses of slender acid-fast bacilli in the necrotic centers of lesions and within surrounding giant cells.

Bacterial Meningoencephalitis and Ventriculitis Due to Migrating Plant Foreign Bodies in Three Dogs

Regional suppurative meningoencephalitis and ventriculitis of variable chronicity was diagnosed in three young dogs residing in Colorado. Grass awns were grossly identified in the right occipital cortex of one dog and in the right lateral ventricle of another. Intralesional plant material was microscopically evident in the dura mater overlying the right occipital cortex of the third dog. One grass awn was identified as a floret of Hordeum jabatum. In each case, aerobic culture of brain tissue identified multiple isolates of bacteria. The dogs presented with clinically variable, rapidly progressive neurologic dysfunction, including tetraplegia, depressed mentation, and episodic extensor rigidity, ataxia, circling, stupor, vocalization, and head-pressing. Encephalitis due to bacteria introduced from migrating plant foreign material is a potential sequela of intranasal, periocular, or pharyngeal foreign bodies.

Necrotizing Meningoencephalitis and Pneumonitis in a Simian Immunodeficiency Virus—infected Rhesus Macaque due to Acanthamoeba

Free-living amoebae of the genus Acanthamoeba can cause a fatal disease of the brain in humans called granulomatous amoebic encephalitis. We present a case of meningoencephalitis and pneumonitis in a simian immunodeficiency virus (SIV)-infected rhesus macaque caused by Acanthamoeba sp. The animal became ill 176 days after intravenous inoculation with SIVmac251 after a short history of weight loss and a sudden onset of hind limb paresis and abnormal head movements. Histopathologic examination of hematoxylin and eosin-stained tissues revealed multifocal to coalescing necrotizing neutrophilic meningoencephalitis and pneumonitis. Immunofluorescence and polymerase chain reaction were used to identify the genus of amoeba as Acanthamoeba. Immunohistochemistry of immune cell markers was used to characterize the animal's immune response to the opportunistic amoebic infection with features of both innate and adaptive cell-mediated immunity. Although not previously reported, the potential transmission to humans, either through environmental contamination or contact with an infected animal, makes this disease a threat to laboratory animal care staff and pathologists.

Seasonal Meningoencephalitis in Holstein Cattle Caused by Naegleria Fowleri

Primary amoebic meningoencephalitis is a fulminant infection of the human central nervous system caused by Naegleria fowleri, a free-living amoeba that thrives in artificially or naturally heated water. The infection usually is acquired while bathing or swimming in such waters. The portal of entry is the olfactory neuroepithelium. This report describes fatal meningoencephalitis caused by N. fowleri in Holstein cattle that consumed untreated surface water in an area of California where summer temperatures at times exceed 42°C. In the summers of 1998 and 1999, severe multifocal necrosuppurative hemorrhagic meningoencephalitis was observed in brain samples from nine 10-20-month-old heifers with clinical histories of acute central nervous system disease. Olfactory lobes and cerebella were most severely affected. Lesions were also evident in periventricular and submeningeal neuropil as well as olfactory nerves. Naegleria fowleri was demonstrated by immunohistochemistry in brain and olfactory nerve lesions and was isolated from one brain. Even though cultures of drinking water did not yield N. fowleri, drinking water was the likely source of the amoeba. The disease in cattle closely resembles primary amoebic meningoencephalitis in humans. Naegleria meningoencephalitis should be included among differential diagnoses of central nervous system disease in cattle during the summer season in areas with high ambient temperatures.

Comparison between DNA Detection in Trigeminal Nerve Ganglia and Serology to Detect Cattle Infected with Bovine Herpesviruses Types 1 and 5

Bovine herpesviruses (BoHVs) types 1 (BoHV-1) and 5 (BoHV-5) are alphaherpesviruses of major importance to the bovine production chain. Such viruses are capable of establishing latent infections in neuronal tissues. Infected animals tend to develop a serological response to infection; however, such response—usually investigated by antibody assays in serum—may eventually not be detected in laboratory assays. Nevertheless, serological tests such as virus neutralization (VN) and various enzyme-linked immunosorbent assays (ELISAs) are widely employed to check individual or herd status of BoHV infections. The correlation between detection of antibodies and the presence of viral nucleic acids as indicatives of infection in infected cattle has not been deeply examined. In order to investigate such correlation, 248 bovine serum samples were tested by VN to BoHV-1 and BoHV-5, as well as in a widely employed (though not type-differential) gB ELISA (IDEXX IBR gB X2 Ab Test) in search for antibodies to BoHVs. Immediately after blood withdrawal, cattle were slaughtered and trigeminal ganglia (TG) excised for DNA extraction and viral nucleic acid detection (NAD) by nested PCR. Neutralizing antibodies to BoHV-1 and/or BoHV-5 were detected in 44.8% (111/248) of sera, whereas the gB ELISA detected antibodies in 51.2% (127/248) of the samples. However, genomes of either BoHV-1, BoHV-5, or both, were detected in TGs of 85.9% (213/248) of the animals. These findings reveal that the assays designed to detect antibodies to BoHV-1 and/or BoHV-5 employed here may fail to detect a significant number of latently infected animals (in this study, 35.7%). From such data, it is clear that antibody assays are poorly correlated with detection of viral genomes in BoHV-1 and BoHV-5-infected animals.

Detection of Circovirus in Foxes with Meningoencephalitis, United Kingdom, 2009-2013

A fox circovirus was identified in serum samples from foxes with unexplained neurologic signs by using viral metagenomics. Fox circovirus nucleic acid was localized in histological lesions of the cerebrum by in situ hybridization. Viruses from the family Circoviridae may have neurologic tropism more commonly than previously anticipated.

Meningoencephalitis and Listeria monocytogenes, Toxoplasma gondii and Brucella spp. coinfection in a dolphin in Italy

Listeria monocytogenes, Toxoplasma gondii and Brucella spp. can infect a wide range of species, including humans. In cetaceans, meningoencephalitis has been associated with T. gondii and Brucella spp. infection, whereas to our knowledge, L. monocytogenes infection has not previously been reported. Meningoencephalitis and L. monocytogenes, T. gondii and Brucella spp. were identified by means of both direct and indirect laboratory techniques in an adult female striped dolphin Stenella coeruleoalba found stranded in January 2015 on the Ligurian Sea coast, northwestern Italy. The animal was emaciated, and histopathology disclosed severe meningoencephalitis. The nature of the inflammatory response and intra-lesional protozoa were consistent with a mixed infection by L. monocytogenes, T. gondii and Brucella spp. We believe this is an unprecedented case of infection by 3 zoonotic pathogens and also the first bacteriologically confirmed case report of neurolisteriosis in cetaceans. Cerebral toxoplasmosis and neurobrucellosis may have led to the animal's disorientation and stranding, with L. monocytogenes having likely exacerbated the coinfection leading to the demise of this dolphin.

Th17 Pathway As a Target for Multipotent Stromal Cell Therapy in Dogs: Implications for Translational Research

Detrimental Th17 driven inflammatory and autoimmune disease such as Crohn’s disease, graft versus host disease and multiple sclerosis remain a significant cause of morbidity and mortality worldwide. Multipotent stromal/stem cell (MSC) inhibit Th17 polarization and activation in vitro and in rodent models. As such, MSC based therapeutic approaches are being investigated as novel therapeutic approaches to treat Th17 driven diseases in humans. The significance of naturally occurring diseases in dogs is increasingly recognized as a realistic platform to conduct pre-clinical testing of novel therapeutics. Full characterization of Th17 cells in dogs has not been completed. We have developed and validated a flow-cytometric method to detect Th17 cells in canine blood. We further demonstrate that Th17 and other IL17 producing cells are present in tissues of dogs with naturally occurring chronic inflammatory diseases. Finally, we have determined the kinetics of a canine specific Th17 polarization in vitro and demonstrate that canine MSC inhibit Th17 polarization in vitro, in a PGE₂ independent mechanism. Our findings provide fundamental research tools and suggest that naturally occurring diseases in dogs, such as inflammatory bowel disease, may be harnessed to translate novel MSC based therapeutic strategies that target the Th17 pathway.