M. Pumarola

Pathologic and Immunocytochemical Studies of Morbillivirus Infection in Striped Dolphins (Stenella coeruleoalba)

Hundreds of striped dolphins (Stenella coeruleoalba) died along the Spanish Mediterranean coast during the second half of 1990. We necropsied 58 dolphins. Partial collapse of the lungs with patchy atelectasis, subcutaneous edema, icterus, and stomatitis were the most prominent gross morphologic changes. Histologically, a bronchiolo-interstitial pneumonia was the most frequent lesion (72% of the animals). It was characterized by hyperplasia of alveolar epithelial type II cells and formation of multinucleate syncytia in alveolar and bronchiolar lumina. Other prominent lesions were encephalitis (69%), lymphoid depletion, and formation of multinucleate syncytia in the cortex of lymph nodes. The distribution of morbillivirus antigen was investigated in 23 wellpreserved dolphins using a monoclonal antibody against the hemagglutinin glycoprotein of phocine distemper virus. Positive immunostaining was found in brain (77%), in lung (70%), and in mesenteric (61%), mediastinal (47%), and prescapular (45%) lymph nodes. Phocine distemper virus antigen was demonstrated less frequently in trachea, stomach, biliary epithelium, intestine, kidney, and mammary gland. Necrotizing-hemorrhagic pneumonia and encephalitis due to Aspergillus fumigatus were seen in three dolphins, whereas two animals had lesions of toxoplasmosis. Changes in our dolphins were similar to those caused by distemper in seals and porpoises. The origin of the dolphin virus and the relationships among dolphin, seal, and porpoise morbilliviruses are unknown.

AGE-RELATED CHANGES IN THE BRAIN OF THE DOG

Although many age-related changes have been described in the nervous system of different species, few authors have specifically studied the topic. Knowledge of such changes is essential to veterinary pathologists, who must distinguish the lesions of specific pathologic processes from those arising as a result of normal aging. The brains of 20 old dogs, ranging in age from 8 to 18 years, were compared with those of 10 young dogs using routine staining techniques (hematoxilin and eosin, periodic acid-Schiff), special staining techniques (periodic acid-methenamine silver stain), and immunohistochemical techniques to detect glial fibrillary acid protein, neurofilaments, ubiquitin, and β-amyloid. Changes affected meninges and choroid plexuses, meningeal and parenchymal vessels, neurons, and glial cells. Of special interest was the presence of polyglucosan bodies, cerebrovascular amyloid deposition, senile plaques, and ubiquitinated bodies. Some of the age-related changes found, particularly lipofuscin, polyglucosan bodies, and β-amyloid protein deposition, may play a role in the pathogenesis of the canine cognitive dysfunction syndrome. The dog could be used as a natural animal model for the study of normal aging and human neurodegenerative diseases.

Whole body correction of mucopolysaccharidosis IIIA by intracerebrospinal fluid gene therapy

For most lysosomal storage diseases (LSDs) affecting the CNS, there is currently no cure. The BBB, which limits the bioavailability of drugs administered systemically, and the short half-life of lysosomal enzymes, hamper the development of effective therapies. Mucopolysaccharidosis type IIIA (MPS IIIA) is an autosomic recessive LSD caused by a deficiency in sulfamidase, a sulfatase involved in the stepwise degradation of glycosaminoglycan (GAG) heparan sulfate. Here, we demonstrate that intracerebrospinal fluid (intra-CSF) administration of serotype 9 adenoassociated viral vectors (AAV9s) encoding sulfamidase corrects both CNS and somatic pathology in MPS IIIA mice. Following vector administration, enzymatic activity increased throughout the brain and in serum, leading to whole body correction of GAG accumulation and lysosomal pathology, normalization of behavioral deficits, and prolonged survival. To test this strategy in a larger animal, we treated beagle dogs using intracisternal or intracerebroventricular delivery. Administration of sulfamidase-encoding AAV9 resulted in transgenic expression throughout the CNS and liver and increased sulfamidase activity in CSF. High-titer serum antibodies against AAV9 only partially blocked CSF-mediated gene transfer to the brains of dogs. Consistently, anti-AAV antibody titers were lower in CSF than in serum collected from healthy and MPS IIIA-affected children. These results support the clinical translation of this approach for the treatment of MPS IIIA and other LSDs with CNS involvement.

Abnormal synaptic protein expression and cell death in murine scrapie

Abstract. Reduced expression of synaptophysin p38, synaptic-associated protein of molecular weight 25,000 (SNAP-25), syntaxin-1, synapsin-1, and α- and β-synuclein, matching the distribution of spongiform degeneration, was found in the neurological phase of scrapie-infected mice. In addition, synaptophysin and SNAP-25 were accumulated in isolated neurons, mainly in the thalamus, midbrain and pons, and granular deposits of α- and β-synuclein were present in the neuropil of the same areas. No modifications in the steady state levels of Bcl-2, Bax, Fas and Fas ligand were observed following infection. Yet antibodies against the c-Jun N-terminal peptide, which cross-react with products emerging after caspase-mediate proteolysis, recognize coarse granular deposits in the cytoplasm of reactive microglia. In situ end-labeling of nuclear DNA fragmentation showed positive nuclei with extreme chromatin condensation in the thalamus, pons, hippocampus and, in particular, the granular layer of the cerebellum. More importantly, expression of cleaved caspase-3, a major executioner of apoptosis, was seen in a few cells in the same regions, thus indicating that cell death by apoptosis in scrapie-infected mice is associated with caspase-3 activation. The present findings support the concept that synaptic pathology is a major substrate of neurological impairment and that caspase-3 activation may play a pivotal role in apoptosis in experimental scrapie. However, there is no correlation between decreased synaptic protein expression and caspase-3-associated apoptosis, which suggests that in addition to abnormal prion protein deposition, there may be other factors that distinctively influence synaptic vulnerability and cell death in murine scrapie.

Magnetic resonance imaging findings in 40 dogs with histologically confirmed intracranial tumours.

Magnetic resonance (MR) images of 40 dogs with histologically confirmed primary and secondary intracranial tumours were reviewed. Forty-one tumours were diagnosed by means of MR imaging (MRI). MRI findings allowed diagnosis of a neoplastic lesion in 37/41 cases. Based on MRI features, differentiation between neoplastic and non-neoplastic lesions was possible in 24/27 (89%) primary brain tumours and in 13/14 (92%) secondary brain tumours. Diagnosis of tumour type based on MRI features was correct in 19/27 (70%) primary tumours and in 13/14 secondary tumours. The results of this study show that MRI is a good diagnostic imaging modality to detect neoplastic lesions and to diagnose tumour type in dogs. However, as some neoplasms show equivocal MRI features the technique has limitations in the detection of some intracranial tumours and in predicting tumour type.

International veterinary epilepsy task force consensus report on epilepsy definition, classification and terminology in companion animals

Dogs with epilepsy are among the commonest neurological patients in veterinary practice and therefore have historically attracted much attention with regard to definitions, clinical approach and management. A number of classification proposals for canine epilepsy have been published during the years reflecting always in parts the current proposals coming from the human epilepsy organisation the International League Against Epilepsy (ILAE). It has however not been possible to gain agreed consensus, “a common language”, for the classification and terminology used between veterinary and human neurologists and neuroscientists, practitioners, neuropharmacologists and neuropathologists. This has led to an unfortunate situation where different veterinary publications and textbook chapters on epilepsy merely reflect individual author preferences with respect to terminology, which can be confusing to the readers and influence the definition and diagnosis of epilepsy in first line practice and research studies.In this document the International Veterinary Epilepsy Task Force (IVETF) discusses current understanding of canine epilepsy and presents our 2015 proposal for terminology and classification of epilepsy and epileptic seizures. We propose a classification system which reflects new thoughts from the human ILAE but also roots in former well accepted terminology. We think that this classification system can be used by all stakeholders.

CANINE INFLAMMATORY MYOPATHY: ANALYSIS OF CELLULAR INFILTRATES

Inflammatory myopathies (IMs) occur relatively frequently in dogs, and, with the exception of masticatory muscle myositis (MMM), have not been characterized. This study analyzed the distribution and types of cellular infiltrates in 21 cases of generalized IM, 3 cases of focal IM (MMM), and 1 case with features of both generalized and focal IM, using a panel of monoclonal antibodies to cell surface markers. In generalized IM, mononuclear cells showed an endomysial and perimysial distribution with invasion of non‐necrotic fibers similar to human IM. T lymphocytes with T‐cell receptor (TCR)αβ predominated. Distinct differences were seen in MMM including prominent B‐cell infiltration, dendritic cells and macrophages in greater numbers than T cells, and numerous T cells with TCRγδ. Thus, generalized IM and MMM appear to be distinct diseases with different mechanisms. Canine generalized IM may be an important animal model for human IM. Muscle Nerve 29: 782–789, 2004

Mapping of aggrecan, hyaluronic acid, heparan sulphate proteoglycans and aquaporin 4 in the central nervous system of the mouse

The extracellular matrix (ECM) of the central nervous system (CNS) is found dispersed in the neuropil or forming aggregates around the neurons called perineuronal nets (PNNs). The ECM mainly contains chondroitin sulphate proteoglycans (CSPG), hyaluronic acid (HA) and tenascin-R. Heparan sulphate proteoglycans (HSPG) can also be secreted in the ECM or be part of the cell membrane. The ECM has a heterogeneous distribution which has been linked to several functions, such as specific regional maintenance of hydrodynamic properties in the CNS, in which aquaporins (AQP) play an important role. AQP are a family of membrane proteins which acts as a water channel and AQP4 is the most abundant isoform in the brain. Nevertheless the importance of these proteins, their distribution and correlation in the whole CNS of mice is only partially known. In the present study, the histochemical and immunohistochemical distribution of PNNs, using Wisteria floribunda agglutinin (WFA), aggrecan, HA, HSPGs and AQP4 is described, and their perineuronal and neuropil staining has been semi-quantitatively evaluated in the whole CNS of mice. The results showed that the aggrecan, HA and HSPGs perineuronal distribution coincided partially and this could be related to ECM functional properties. AQP4 showed a heterogeneous distribution throughout the CNS. In some areas, an inverse correlation between AQP4 and ECM components has been observed, suggesting a complementary role for both in the maintenance of water homeostasis. A common location for AQP4 and HSPGs has also been observed in CNS neuropil.

Canine leishmaniasis associated with systemic vasculitis in two dogs

Two cases of canine leishmaniasis associated with systemic necrotizing vasculitis are described. The main macroscopic lesions were haemorrhagic in type; histopathological changes confirmed a vascular lesion affecting small arteries of several organs (skin, intestinal tract, kidney, urinary bladder, mesenteric lymph nodes, adrenal gland, myocardium, lung, eye and choroid plexus). The presence of the parasite was confirmed with a specific immunocytochemical stain. The possibility of an immunological aetiology of the vasculitis and its classification is discussed.

Malignant Epithelioid Schwannoma Affecting the Trigeminal Nerve of a Dog

A malignant epithelioid schwannoma was diagnosed affecting the trigeminal nerve of an 11-year-old dog. Neurologic abnormalities included an altered mental status, ataxia, left head tilt, postural reaction deficits of all four limbs, a pronounced left masticatory muscle atrophy, and absent left facial sensation. Histologically, a densely arranged epithelioid population with a very high mitotic index was surrounded by a spindle-shaped cell proliferation characteristic of schwannomas. Both cell populations stained positively for vimentin, but only spindle cells were occassionally positive for S-100 protein. The histologic and immunohistochemical features of this tumor were consistent with those found in human epithelioid schwannomas.