Neurogenesis in a young dog with epileptic seizures

Epileptic seizures can lead to various reactions in the brain, ranging from neuronal necrosis and glial cell activation to focal structural disorganization. Furthermore, increased hippocampal neurogenesis has been documented in rodent models of acute convulsions. This is a report of hippocampal neurogenesis in a dog with spontaneous epileptic seizures. A 16-week-old epileptic German Shepherd Dog had marked neuronal cell proliferation (up to 5 mitotic figures per high-power field and increased immunohistochemical expression of proliferative cell nuclear antigen) in the dentate gyrus accompanied by microglial and astroglial activation. Some granule cells expressed doublecortin, a marker of immature neurons; mitotically active cells expressed neuronal nuclear antigen. No mitotic figures were found in the brain of age-matched control dogs. Whether increased neurogenesis represents a general reaction pattern of young epileptic dogs should be investigated.     

A case of spontaneous myocardial necrosis and cerebral ischemic lesions in a laboratory beagle dog

A beagle dog treated with saline as a control animal in a preclinical study was euthanized due to sudden systemic deterioration. On histopathological examination, contraction band necrosis of myocardial cells was observed widely in the left ventricular wall, including the papillary muscle and apex, and observed slightly in the ventricular septum and left atrium. In the brain, necrosis was observed in neurons and glia of the cerebral cortex, hippocampal pyramidal cells, glial cells of the rostral commissure and Purkinje cells of the cerebellar vermis. It is highly probable that the marked systemic deterioration was caused by cardiac dysfunction due to the spontaneous contraction band necrosis of the myocardial cells, although the pathogenesis of the myocardial lesions remains unclear. Given the distribution of neuronal necrosis in the brain, it is likely that these lesions resulted from the ischemia responsible for acute cardiac failure.     

IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING FEATURES OF A CEREBRAL HEMANGIOBLASTOMA IN A DOG

The magnetic resonance (MR) imaging features of a cerebral hemangioblastoma in a 9‐year‐old dog are described. Imaging revealed a well‐defined contrast‐enhancing lesion of the rostral forebrain that appeared extraparenchymal. Histopathology of the excised mass showed clusters of small blood vessels interspersed with interstitial cells staining positive for neuronal specific enolase, features consistent with a cerebral hemangioblastoma; the mass also appeared intraparenchymal after further immunohistochemistry study. This neoplasm should be considered a rare differential diagnosis for intracranial masses in dogs.     

Evaluation of proliferative disorders in canine bone marrow by use of flow cytometric scatter plots and monoclonal antibodies

The combination of flow cytometric scatterplot analysis and specific monoclonal antibodies was used to evaluate the lineage of cells from six dogs with proliferative disorders of bone marrow. Scatterplot analysis was used to identify mature and immature myeloid and erythroid cells. The immunophenotype of cells in the immature myeloid gate was determined by labeling cells with four monoclonal antibodies. These results were compared to results of cytologic and cytochemical evaluation. The immunophenotype of a dog with a diagnosis of myelogenous leukemia was a cluster of differentiation-18 (CD-18) positive, CD-14 negative, Thy-1 negative, and a major histocompatibility complex (MHC) class II negative. The immunophenotype of a dog with a diagnosis of myelomonocytic leukemia was CD-18 positive, CD-14 positive, Thy-1 positive, and MHC class II positive. Although this phenotype clearly differentiated myelomonocytic leukemia from myelogenous leukemia, it was similar to the immunophenotype of dogs with a diagnosis of malignant histiocytosis or hemophagocytic syndrome. The immunophenotype of two dogs with myelodysplastic syndrome was CD-18 positive and CD-14 negative. Results for Thy-1 and MHC class II were variable. As additional lineage-specific monoclonal antibodies become available, immunophenotyping should become a valuable tool for determination of the lineage of cells in canine myeloproliferative disorders.     

Detection of an autoantibody from Pug dogs with necrotizing encephalitis (Pug dog encephalitis).

An autoantibody against canine brain tissue was detected in the cerebrospinal fluid (CSF) and serum of two Pug dogs (Nos. 1 and 2) by indirect immunofluorescence assay (IFA). Dog No. 1, a 2-year-old male, exhibited severe depression, ataxia, and generalized seizures and died 2 months after the onset of symptoms. Dog No. 2, a 9-month-old male, exhibited severe generalized seizures and died 17 months after the onset of symptoms. Histopathologic examination revealed a moderate to severe multifocal accumulation of lymphocytes, plasma cells, and a few neutrophils in both the gray and white matter of the cerebrum in dog No. 1. In dog No. 2, the cellular infiltrates were mild, but there was a severe, diffuse, and multifocal necrosis in the cerebral cortex with prominent astrocytosis. With the aid of IFA using fluorescein isothiocyanate-labeled antidog IgG goat serum and a confocal imaging system, specific reactions for glial cells were detected in the CSF of these Pug dogs but not in six canine control CSF samples. Double-labeling IFA using CSF from these Pug dogs and a rabbit antiserum against glial fibrillary acidic protein (GFAP) revealed that the autoantibody recognized GFAP-positive astrocytes and their cytoplasmic projections. By immunoblot analysis, the autoantibody from CSF of these Pug dogs recognized two common positive bands at 58 and 54 kd, which corresponded to the molecular mass of human GFAP. The role of this autoantibody for astrocytes is not yet clear. However, if the presence of the autoantibody is a specific feature of Pug dog encephalitis, it will be a useful clinical diagnostic marker and a key to the pathogenesis of this unique canine neurologic disease.     

Ganglioneuroma in the urinary bladder of a dog

An 11-year-old male Labrador retriever presented with chronic oliguria. Ultrasonography findings revealed a protruding mass at the neck of the urinary bladder. A cystotomy was performed, and the mass was removed by ligation with surgical sutures. Histopathological examination revealed conspicuous foci with a variable number of ganglion cells in the tumor and abundant interwoven bundles of schwannian cells with fine fibers. The ganglion cells were positive for neuron-specific enolase and neurofilament. The schwannian cells were positive for vimentin, S-100 protein, and glial fibrillary acidic protein. Thus, according to the classification of tumor with neuronal cell differentiation, the urinary tumor was diagnosed as a ganglioneuroma.     

Loss of glutamine synthetase immunoreactivity from the retina in canine primary glaucoma

Purpose Changes in retinal glutamate distribution occur in primary glaucoma (PG) in dogs. Although the redistribution resembles that induced by ischemia, decreases in glutamine synthetase (GS) activity may also induce a similar glutamate redistribution. We examined the distribution of GS, glutamate, and glial fibrillary acidic protein (GFAP), a marker for reactive glia, in PG retinas by immunohistochemistry to determine whether decreases in GS and formation of reactive glia are associated with glutamate redistribution and neuronal damage. Animals Sections from 14 control dog eyes and 22 eyes from dogs with PG. Methods Sections from 14 control and 22 glaucomatous globes were immunohistochemically stained for GS, glial fibrillary acidic protein or glutamate. Results In semiquantitative immunogold studies, decreases in GS staining density were strongly correlated with glutamate redistribution and neuronal damage. In less quantitative immunoperoxidase staining of acute (≤ 5 days after clinical signs) and chronic PG retinas, GS immunoreactivity was decreased in focal regions of some acute PG retinas, and there were widespread decreases in chronic PG retinas. GFAP immunoreactivity was increased in Müller cells primarily in severely damaged regions of chronic PG retinas. Conclusions Decreases in GS immunoreactivity were associated with glutamate redistribution. These decreases in GS occurred even in mildly damaged regions of retina before retinal thinning. Reactive Müller cells were seen primarily in chronic PG in severely damaged regions. Decreases in GS may potentiate ischemia‐induced early glutamate redistribution and neuronal damage in canine PG.     

Ganglioglioma in the thalamus of a puppy

A solitary brain mass of a 4-month-old miniature dachshund showing seizure-like neurological signs was examined histopathologically. At necropsy a white tumor mass, replacing the thalamus, approximately 1.5 cm in diameter, was found. There was cystic space filled with yellowish pale fluid in the central area of the tumor mass. Histopathological examination revealed that the mass consisted of irregularly arranged well-differentiated neuronal and glial cells, and multifocal mineral deposits. The neuronal cells had a large clear nucleus and various amount of Nissl substances in the cytoplasm. Some neural cells were bi-nucleated. Neither mitotic figures nor proliferating cell nuclear antigen (PCNA)-positive nuclei was found in the neuronal cells. Immunostaining for glial fibrillary acidic protein (GFAP) revealed diffuse proliferation of GFAP-positive glial cells and their processes, while these glial cells did not show apparent cellular atypism, mitotic activity, or PCNA-immunoreactivity. Accordingly, the present tumor was diagnosed as ganglioglioma, and hamartomatous histogenesis might be possible.     

Anaplastic ependymoma in the cervical spinal cord of a maltese dog

An 8-year and 6-month-old female Maltese dog showed a stoop with rigidity of her cervix and back. Neurologic examination showed loss of proprioception, and deficiency of pain response. Postmortem examination revealed the neoplastic mass replacing the central area in the cervical spinal cord at the level from 4th to 5th segments. Histologically, the mass was composed of neoplastic ependymal cells. The neoplastic cells showed marked atypism, and occasionally formed ependymal rosettes. Based on the morphologic features, the tumor was diagnosed as anaplastic ependymoma. Immunohistochemistry showed that the neoplastic cells were negative for glial fibrillary acid protein, and slightly positive for vimentin and cytokeratin.     

IMAGING DIAGNOSIS—NEURONAL CEROID LIPOFUSCINOSIS WITH A CHRONIC SUBDURAL HEMATOMA

A subdural hematoma was found to accompany neuronal ceroid lipofuscinosis in an 11‐month‐old Dachshund. Results from clinical, magnetic resonance (MR) imaging, histopathologic, ultrastructural, and molecular assessments are described. The dog had a 3‐month history of progressive neurologic signs. In MR images, there was severe asymmetric cerebral atrophy with a subdural hematoma. Histopathologically, there was autofluorescent, periodic acid–Schiff‐positive lipopigment in neurons and transmission electron microscopy confirmed a typical curvilinear profile of the storage bodies. We hypothesize that rapid brain atrophy contributed to the subdural hematoma formation, a complication not described previously in dogs with neuronal lipofuscinosis.     

Severe involvement of cerebral neopallidum in a dog with hepatic encephalopathy

This report describes a unique distribution of cerebral cortical necrotic lesion, which was diagnosed as hepatic encephalopathy in a 2-year-old Maltese dog. The dog showed splenocaval shunt and small liver with marked hepatocellular fatty degeneration. Histopathologic examination revealed that diffuse laminar cortical necrosis composed of neuronal necrosis, marked infiltration of gitter macrophages, and astrogliosis were found bilaterally in the dorsolateral area of the cerebrum. No necrotic lesions were observed in the cerebral paleopallium and archipallium, the central gray matter, cerebellum, and brain stem. Astrocytes with large and pale nuclei (Alzheimer type II astrocytes) were apparent throughout the brain. Immunohistochemically, a decrease of immunostains for glutamine synthetase and glutamate transporter antibodies was seen in Alzheimer type II astrocytes and neuropil. This is, to our knowledge, the first report of extensive involvement of cerebral neopallidum in canine hepatic encephalopathy.     

Factor VIII-related antigen in canine endothelial neoplasms: an immunohistochemical study

Canine vascular tumors (47 hemangiomas, 36 hemangiosarcomas) were investigated for the endothelial cell marker factor VIII-related antigen (F VIII RAg). The primary antibody was a commercial rabbit anti-human (r/h) F VIII RAg antiserum. All (100%) hemangiomas and 32 (89%) of 36 hemangiosarcomas stained for F VIII RAg. One hemangiosarcoma (3%) was negative, and three tumors (8%) were equivocal in staining. Rarely, the interpretation of stained immature endothelial cells was difficult. The r/h F VIII RAg antibody was a positive marker of normal, reactive, and neoplastic endothelial cells in the dog.     

Gliomatosis cerebri in a dog

Gliomatosis cerebri is a rare tumourous disease of the central nervous system consisting of glial cells characterized by diffuse widespread infiltration and preservation of preformed brain structures. This report describes a case of gliomatosis cerebri in a 9-year-old, male, flat-coated retriever dog with central nervous symptoms. Magnetic resonance imaging of the brain demonstrated ill-defined hyperintense zones of paramedian white matter within the right cerebral hemisphere, brainstem and cerebellum. Histological examination showed a proliferation of tumour cells in the brain structures mentioned. Glial fibrillary acidic protein-immunohistochemistry revealed a lot of fibres positively stained. Based on these findings, the alteration was diagnosed as gliomatosis cerebri.     

Postnatal changes in Rho and Rho-related proteins in the mouse brain

To provide information on the role of Rho, a GTP-binding protein, in postnatal development of the brain cells, the change in the levels of Rho protein and Rho-related proteins was examined in the brain of mice for two weeks after birth, in parallel with the changes in the activity of marker enzymes for neuronal and glial cells. The activities of acetylcholine esterase and choline acetyltransferase of whole brain homogenate, both of which are neuronal marker enzymes, were progressively increased in an age-dependent manner. The activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase, a glial marker enzyme, increased markedly between one and two weeks after birth. In contrast, the levels of RhoA and RhoB in the membrane fraction were decreased during the postnatal period. The amount of Rho GDP dissociation inhibitor, a regulatory protein for Rho, was unchanged, while those of Rho target proteins, Rock-2 and citron, were gradually increased. Since the inactivation of Rho is known to induce neurite extension and neuronal and glial differentiation in vitro, our results suggest that the Rho signalling pathway plays a regulatory role in the postnatal differentiation of neuronal and glial cells in vivo.     

Oligodendroglial gliomatosis cerebri in a poodle

Gliomatosis cerebri (GC) is a rare, diffusely infiltrating, glial cell tumour of neuroepithelial origin. This report describes a case of oligodendroglial GC in a 6-year-old male Poodle with central nervous system symptoms. Computed tomography revealed anomalous parenchyma density and ventricular asymmetry. Cerebrospinal fluid showed elevated protein (30 mg dL(-1)) and nucleated cell count (20 μL(-1)). Presumptive diagnosis of necrotizing meningoencephalitis was made. Because of rapid deterioration of the general condition of the animal, the dog was euthanized. Histologically there was an infiltration of round or ovoid neoplastic cells in the white matter of the left cerebral hemisphere and in leptomeninges. Immunohistochemistry showed that 80% of the neoplastic cells expressed Olig2 and some 50% expressed glial fibrilary acidic protein. On the basis of clinical, histological and immunohistochemical features, a diagnosis of oligodendoglial GC was done. This case represents the first report of a case of oligodendroglial GC in the canid.     

Subcutaneous Soft Tissue Sarcoma with Rhabdoid Features in a Dog

A nine-year-old male beagle dog had a white spherical mass in the subcutis of the left lumbar region. Microscopically, spindle to oval cells diffusely proliferated in the fibrous and myxoid stroma. Many neoplastic cells showed rhabdoid features or vacuolated cytoplasm. Immunohistochemically, the neoplastic cells were positive for vimentin and S100 and partly positive for neuron-specific enolase and glial fibrillary acidic protein but were negative for von Willebrand factor, desmin and α-smooth muscle actin. Ultrastructurally, the neoplastic cells had abundant cytoplasmic processes and desmosome-like structures. Cytoplasmic inclusions of rhabdoid-featured cells in HE sections were composed of aggregates of intermediate filaments, and cytoplasmic vacuoles were identified as an invagination of cytoplasm. Although malignant peripheral nerve sheath tumor was suggested according to these results, the present case was diagnosed as a soft tissue sarcoma with rhabdoid features due to a lack of identification of the basal lamina under electron microscopy.     

A canine peripheral nerve sheath tumor including peripheral nerve fibers

Peripheral nerve sheath tumor was found in a 7-year-old male mongrel dog. The tumors were located in the right cheek subcutis and oral submucosa. Histologically, neoplastic cells were arranged in streaming bundles, occasionally interlacing bundles or whorls of elongated and spindle cells. Cellular atypia was poor and mitotic figures were rarely observed. Ultrastructurally, neoplastic cells had basement membrane, typical of Schwann cells. One bundle of normal peripheral nerve fibers and some myelinated axons were seen within the tumor tissues. Immunohistochemically, neoplastic cells reacted to vimentin, glial fibrillary acidic protein, S-100 protein and neuron specific enolase. In addition to the above immunoreactions, the included nerve fibers were positive for myelin basic protein and neurofilament protein. This paper also discusses immunohistochemical findings on differential diagnosis in comparison with those of canine hemangiopericytomas reported hitherto.     

Blue eye disease porcine rubulavirus (PoRv) infects pig neurons and glial cells using sialo-glycoprotein as receptor

Pig neural cells express glycoproteins with sialylated N-linked oligosaccharide chains (SNOC) which are used by the porcine rubulavirus (PoRv) as receptors. Pig neuronal or glial cell cultures were employed to investigate (a) whether PoRv infects such cells using a molecule expressing SNOC, and (b) the role of viral envelope glycoproteins in establishing the infection. Enriched neuronal or glial cell cultures were exposed to PoRv and infection was detected immunocytochemically. Neuronal cultures prepared from neonatal pigs were treated enzymatically to eliminate sialic acid or N-linked oligosaccharide chains. Primary neural cultures were exposed to anti-HN or anti-F preincubated with PoRv to study the role of the viral glycoproteins. In enriched cultures, PoRv infected neurons and glial cells, and sialic acid expressed in N-linked oligosaccharide chains appeared to play a central role in infection. It was concluded that HN and F viral glycoproteins are required to infect neurons and glial cells.