Multiplex analysis of cytokines in the cerebrospinal fluid of dogs after ischemic stroke reveals elevations in chemokines CXCL1 and MCP-1.

Introduction: Neuroinflammation that occurs in the brain after stroke has been shown to be important to disease pathogenesis and outcomes. The aim of this study was to evaluate a large number of pro- and anti-inflammatory cytokines in dogs with clinically-confirmed, naturally occurring stroke. Materials and methods: Fifteen dogs with a clinical diagnosis of ischemic stroke and ten healthy control dogs were included in the study. A multiplex immunoassay was utilized to evaluate cerebrospinal fluid for GM-CSF, IFN-γ, IL-2, IL-4, IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, IP-10, CXCL1, MCP-1, and TNF-α. Results: Mean concentrations of CXCL1 (stroke-436 pg/ml, control-267 pg/ml, p = 0.01) and MCP-1 (stroke-196 pg/ml, control-66 pg/ml, p ≤ 0.0001) were significantly elevated in dogs with stroke when compared with control dogs. Location and type of infarct, duration of clinical signs, and use of anti-inflammatory medications were not associated with differences in cytokine concentration. Discussion: CXCL1 and MCP-1 may play a role in naturally occurring canine stroke and represent targets for future research.

Screening for Viral Nucleic Acids in the Cerebrospinal Fluid of Dogs With Central Nervous System Inflammation.

Central nervous system (CNS) inflammation is a common cause of neurological dysfunction in dogs. Most dogs with CNS inflammation are diagnosed with presumptive autoimmune disease. A smaller number are diagnosed with an infectious etiology. Additionally, at necropsy, a subset of dogs with CNS inflammation do not fit previously described patterns of autoimmune disease and an infectious cause is not readily identifiable. Because viral infection is a common cause of meningoencephalitis in people, we hypothesize that a subset of dogs presented with CNS inflammation have an occult viral infection either as a direct cause of CNS inflammation or a trigger for autoimmunity. The goal of this research was to screen cerebrospinal fluid from a large number dogs with CNS inflammation for occult viral infection. One hundred seventy-two dogs with neurological dysfunction and cerebrospinal fluid (CSF) pleocytosis were identified. Of these, 42 had meningoencephalitis of unknown origin, six had steroid-responsive meningitis-arteritis, one had eosinophilic meningoencephalitis, five had documented infection, 21 had and undetermined diagnosis, and 97 had a diagnosis not consistent with primary inflammatory disease of the CNS (e.g., neoplasia). CSF samples were subsequently screened with broadly reactive PCR for eight viral groups: adenovirus, bunyavirus, coronavirus, enterovirus, flavivirus, herpesvirus, paramyxovirus, and parechovirus. No viral nucleic acids were detected from 168 cases screened for eight viral groups, which does not support occult viral infection as a cause of CNS inflammation in dogs. La Crosse virus (LACV) nucleic acids were detected from four cases in Georgia. Subclinical infection was supported in two of these cases but LACV could not be ruled-out as a cause of infection in the other two cases, suggesting further research is warranted to determine if LACV is an occult cause of CNS inflammation in dogs.

Incidence and risk factors for surgical site infection following enucleation in dogs.

Introduction: Surgical site infections (SSI) increase morbidity, increase treatment costs, and can delay onset of necessary adjunctive therapy. The goal of this retrospective study was to determine the incidence of and risk factors of SSI after enucleation in dogs. Methods: Medical records were searched at one veterinary teaching hospital and identified 280 dogs that underwent enucleation and had an adequate follow-up to assess SSI. Multiple preoperative (e.g., reason for enucleation), peri-operative (e.g., surgical approach and surgeon experience level), and post-operative (e.g., use of post-operative antibiotics or anti-inflammatory medications) variables were assessed as risk factors for development of SSI. Results: The incidence of SSI after enucleation was 5%, and no risk factors for SSI were identified. Dogs that received cephalexin as a prophylactic post-operative antibiotic were statistically more likely to develop SSI versus those that received a different post-operative antibiotic (p = 0.045). However, the clinical significance of this finding is unclear as administration of prophylactic post-operative antibiotics overall did not reduce the risk of SSI in the population evaluated here. Discussion: No risk factors were identified to guide clinical decision-making for prevention of SSI. Additionally, the results do not support the use of prophylactic antibiotics after enucleation in dogs.

Poliomyelomalacia in three dogs that underwent hemilaminectomy for intervertebral disk herniation.

CASE DESCRIPTION: 3 dogs were examined because of a sudden onset of signs of pain (1 dog) or paraparesis (2 dogs). CLINICAL FINDINGS: Neurologic findings consisted of myelopathy affecting the lumbar intumescence (1 dog) and T3-L3 myelopathy (2 dogs). In all dogs, MRI revealed spinal cord compression caused by L3-4 disk herniation. All dogs underwent routine surgical decompression of the intervertebral disk herniation. During MRI and decompressive surgery, physiologic variables were monitored. Immediately after surgery, all dogs were paraplegic with pelvic limb neurologic dysfunction consistent with myelopathy affecting the L4 through caudal spinal cord segments. TREATMENT AND OUTCOME: Within 24 hours after surgery, repeated MRI in all dogs revealed hyperintensity in the spinal cord gray matter of the lumbar intumescence on T2-weighted images. In the absence of neurologic improvement, dogs were euthanized at 3, 91, and 34 days after surgery. Postmortem microscopic examination of each dog's spinal cord at the lumbar intumescence revealed necrosis of the gray matter with relative white matter preservation suggestive of an ischemic injury. CLINICAL RELEVANCE: Dramatic neurologic deterioration following decompressive surgery for intervertebral disk herniation in dogs may be associated with the development of poliomyelomalacia secondary to ischemia. In these 3 dogs, ischemia developed despite probable maintenance of normal spinal cord blood flow and perfusion during anesthesia. To exclude other causes, such as compression or hemorrhage, MRI was repeated and revealed hyperintensity of the spinal cord gray matter on T2-weighted images, which microscopically corresponded with ischemic neurons and neuronal loss.

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.

Encéphalite à Cladophialophora chez un alpaga. Une femelle alpaga de race Huacaya âgée de 4 ans fut évaluée pour des signes neurologiques aigus incluant un décubitus et une inclinaison de la tête à gauche. L'examen des nerfs crâniens a révélé un affaissement de l'oreille gauche, une déviation vers la droite du museau, une mydriase de l'oeil gauche, une absence de réponse à la menace, l'absence bilatérale de réflexe pupillaire lorsqu'une lumière était pointée dans l'oeil gauche, et un nystagmus horizontal bilatéral avec phase rapide vers la droite. Des lésions intra-crâniales multifocales étaient suspectées. Un examen par tomodensitométrie révéla une masse intra-crâniale. L'examen post-mortem, l'histopathologie et le séquençage d'un produit de réaction d'amplification en chaîne par la polymérase confirmèrent un diagnostic de méningo-encéphalite phaeohyphomycotique causée par Cladophialophora bantiana.Message clinique clé :L'examen par imagerie diagnostique de pointe (tomodensitométrie) fut utile afin d'arriver à un diagnostic de masse intra-crâniale chez un alpaga avec des signes neurologiques aigus, plus tard confirmé par une phaeohyphomycose du système nerveux central (CNS). Bien que peu fréquente, une infection fongique intra-crâniale devrait être considérée comme un diagnostic différentiel chez des camélidés présentant des signes du CNS, particulièrement s'ils ne répondent pas à un traitement initial avec des antimicrobiens et des anthelmintiques.(Traduit par Dr Serge Messier).

Correlation of MRI with the Neuropathologic Changes in Two Cats with Bromethalin Intoxication.

Two cats were presented with multifocal neurological signs. One cat's signs progressed over 2 wk; the other cat progressed over 5 days. Examinations were consistent with a process involving the prosencephalon, vestibular system, and general proprioceptive/upper motor neuron systems. MRI of the brain and cervical spinal cord reveal widespread T2 hyperintensity of the white matter. Affected areas included the cerebrum, cerebral peduncles, corticospinal tracts of the pons and medulla, and the cerebellum. T2 hyperintensity was present in all funiculi of the spinal cord. Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps were consistent with cytotoxic or intramyelinic edema. Differential diagnosis included toxic or metabolic/degenerative leukoencephalopathies. Necropsies revealed widespread spongy degeneration of the central nervous system white matter. Toxicologic assays of liver specimens revealed desmethylbromethalin, a metabolite of bromethalin. Bromethalin is a rodenticide that causes uncoupling of oxidative phosphorylation. Antemortem diagnosis is challenging. DWI and ADC maps were instrumental in narrowing the differential diagnosis and raised the index of suspicion for bromethalin. Bromethalin intoxication should be considered in all animals with a progressive course of multifocal neurologic deficits. MRI, specifically, DWI and ADC maps, may serve as a biomarker of cytotoxic or intramyelinic edema associated with spongiform leukoencephalomyelopathy.

Identification of novel genetic risk loci in Maltese dogs with necrotizing meningoencephalitis and evidence of a shared genetic risk across toy dog breeds.

Necrotizing meningoencephalitis (NME) affects toy and small breed dogs causing progressive, often fatal, inflammation and necrosis in the brain. Genetic risk loci for NME previously were identified in pug dogs, particularly associated with the dog leukocyte antigen (DLA) class II complex on chromosome 12, but have not been investigated in other susceptible breeds. We sought to evaluate Maltese and Chihuahua dogs, in addition to pug dogs, to identify novel or shared genetic risk factors for NME development. Genome-wide association testing of single nucleotide polymorphisms (SNPs) in Maltese dogs with NME identified 2 regions of genome-wide significance on chromosomes 4 (chr4:74522353T>A, p = 8.1×10-7) and 15 (chr15:53338796A>G, p = 1.5×10-7). Haplotype analysis and fine-mapping suggests that ILR7 and FBXW7, respectively, both important for regulation of immune system function, could be the underlying associated genes. Further evaluation of these regions and the previously identified DLA II locus across all three breeds, revealed an enrichment of nominal significant SNPs associated with chromosome 15 in pug dogs and DLA II in Maltese and Chihuahua dogs. Meta-analysis confirmed effect sizes the same direction in all three breeds for both the chromosome 15 and DLA II loci (p = 8.6×10-11 and p = 2.5×10-7, respectively). This suggests a shared genetic background exists between all breeds and confers susceptibility to NME, but effect sizes might be different among breeds. In conclusion, we identified the first genetic risk factors for NME development in the Maltese, chromosome 4 and chromosome 15, and provide evidence for a shared genetic risk between breeds associated with chromosome 15 and DLA II. Last, DLA II and IL7R both have been implicated in human inflammatory diseases of the central nervous system such as multiple sclerosis, suggesting that similar pharmacotherapeutic targets across species should be investigated.

Identification of risk loci for necrotizing meningoencephalitis in Pug dogs.

Due to their unique population structure, purebred dogs have emerged as a key model for the study of complex genetic disorders. To evaluate the utility of a newly available high-density canine whole-genome array with >170,000 single nucleotide polymorphisms (SNPs), genome-wide association was performed on a small number of case and control dogs to determine disease susceptibility loci in canine necrotizing meningoencephalitis (NME), a disorder with known non-Mendelian inheritance that shares clinical similarities with atypical variants of multiple sclerosis in humans. Genotyping of 30 NME-affected Pug dogs and 68 healthy control Pugs identified 2 loci associated with NME, including a region within dog leukocyte antigen class II on chromosome 12 that remained significant after Bonferroni correction. Our results support the utility of this high-density SNP array, confirm that dogs are a powerful model for mapping complex genetic disorders and provide important preliminary data to support in depth genetic analysis of NME in numerous affected breeds.

Broadly reactive pan-paramyxovirus reverse transcription polymerase chain reaction and sequence analysis for the detection of Canine distemper virus in a case of canine meningoencephalitis of unknown etiology.

Despite the immunologic protection associated with routine vaccination protocols, Canine distemper virus (CDV) remains an important pathogen of dogs. Antemortem diagnosis of systemic CDV infection may be made by reverse transcription polymerase chain reaction (RT-PCR) and/or immunohistochemical testing for CDV antigen; central nervous system infection often requires postmortem confirmation via histopathology and immunohistochemistry. An 8-month-old intact male French Bulldog previously vaccinated for CDV presented with multifocal neurologic signs. Based on clinical and postmortem findings, the dog's disease was categorized as a meningoencephalitis of unknown etiology. Broadly reactive, pan-paramyxovirus RT-PCR using consensus-degenerate hybrid oligonucleotide primers, combined with sequence analysis, identified CDV amplicons in the dog's brain. Immunohistochemistry confirmed the presence of CDV antigens, and a specific CDV RT-PCR based on the phosphoprotein gene identified a wild-type versus vaccinal virus strain. This case illustrates the utility of broadly reactive PCR and sequence analysis for the identification of pathogens in diseases with unknown etiology.