Primary and secondary nervous system involvement occurs in 4% and 5%–12%, respectively, of all canine non-Hodgkin lymphomas. The recent new classification of canine malignant lymphomas, based on the ...human World Health Organization classification, has been endorsed with international acceptance. This histological and immunocytochemical classification provides a unique opportunity to study the histologic anatomic distribution patterns in the central and peripheral nervous system of these defined lymphoma subtypes. In this study, we studied a cohort of 37 dogs with lymphoma, which at necropsy had either primary (n = 1, 2.7%) or secondary (n = 36; 97.3%) neural involvement. These T- (n = 16; 43.2%) or B-cell (n = 21; 56.8%) lymphomas were further classified into 12 lymphoma subtypes, with predominant subtypes including peripheral T-cell lymphoma (PTCL) or diffuse large B-cell lymphoma (DLBCL), respectively. This systematic study identified 6 different anatomically based histologically defined patterns of lymphoma infiltration in the nervous system of dogs. Different and distinct combinations of anatomical patterns correlated with specific lymphoma subtypes. Lymphoma infiltration within the meningeal, perivascular, and periventricular compartments were characteristic of DLBCL, whereas peripheral nerve involvement was a frequent feature of PTCL. Similarly cell counts above 64 cells/μL in cerebrospinal samples correlated best with marked meningeal and periventricular lymphoma infiltration histologically. Prospective studies are needed in order to confirm the hypothesis that these combinations of histological neuroanatomic patterns reflect targeting of receptors specific for the lymphoma subtypes at these various sites.
BACKGROUND: In children, frequent congenital malformations with concomitant agenesis of the corpus callosum are diagnosed by neuroimaging in association with other cerebral malformations, including ...interhemispheric cysts and ventriculomegaly. Similar studies providing full characterization of brain defects by in vivo magnetic resonance imaging (MRI), and correlations with the pertinent anatomic pathologic examinations are absent in veterinary medicine. HYPOTHESIS/OBJECTIVES: Congenital brain defects underlie the neurologic signs observed in Toyger cats selectively bred for a short ear phenotype. ANIMALS: Using proper pedigree analysis and genetic evaluations, 20 related Oriental‐derived crossbred Toyger cats were evaluated. Seven clinically healthy (carrier) cats and 13 clinically affected cats that had neurologic signs, short ear phenotype and concomitant complex brain anomalies were studied. METHODS: Complete physical and neurologic examinations and MRI were performed in all clinically healthy and affected cats. Postmortem and histopathologic examinations were performed in 8 affected cats and 5 healthy cats. RESULTS: Neurologic and MRI investigations confirmed 13 clinically affected cats with structural brain abnormalities. Ventriculomegaly with frequent concomitant supratentorial interhemispheric, communicating ventricular type‐1b cysts and multiple midline and callosal malformations were detected in all cats displaying neurologic signs. Genetic analysis confirmed autosomal recessive mode of inheritance with no chromosomal abnormalities. CONCLUSIONS AND CLINICAL IMPORTANCE: Neuroanatomic dissections and histopathology were helpful for evaluation of abnormalities in midline brain structures, and for the full characterization of cysts. However, MRI was more sensitive for detection of small cysts. In this feline model, MRI diagnosis had extremely good correlation with pathologic abnormalities noted in the subset of animals that were examined by both modalities.
Canine distemper virus commonly infects free-ranging, terrestrial mesopredators throughout the United States. Due to the immunosuppressive effects of the virus, concurrent opportunistic infections ...are also common. Among these, secondary systemic protozoal infections have been described in a number of species. We report an unusual presentation of necrotizing encephalitis associated with Sarcocystis sp in four raccoons and one skunk concurrently infected with canine distemper virus. Lesions were characterized by variably sized necrotizing cavitations composed of abundant mineral admixed with inflammatory cells and protozoa. Sarcocystis sp was confirmed via immunohistochemistry using a monoclonal antibody to Sarcocystis neurona. The pathologic changes are similar to lesions in human AIDS patients infected with Toxoplasma gondii.
A 10-year-old golden retriever dog was referred with a 24-h history of generalized seizures. Magnetic resonance imaging of the brain found no abnormalities on 3 mm transverse sections and the dog was ...subsequently humanely destroyed. Microscopically there was bilaterally symmetrical focal disorganization of cortical grey matter within the tips of the right and left suprasylvian gyri of the temporal cortex. The focal abnormal cortical lamination was characterized by loss of pyramidal neurons with abnormal, irregular, angular, remaining neurons occasionally forming clusters, surrounded by fibrillary astrogliosis and microgliosis and vascular proliferation. These histological findings are consistent with focal cortical dysplasia, a cerebral cortical malformation that causes seizures in people, but not reported previously in the dog.
Neurodegenerative diseases are characterised by selective damage to specific neurons in the nervous system. Interest in such diseases in humans has resulted in considerable progress in the molecular ...understanding of these disorders in recent decades. Numerous neurodegenerative diseases have also been described in domestic animals but relatively little molecular work has been reported.
In the present review, we have classified neurodegenerative disease according to neuroanatomical criteria. We have established two large groups, based on whether the neuronal cell body or its axon was primarily affected. Conditions such as motor neuron diseases, cerebellar degenerations and neuroaxonal dystrophies are discussed in terms of their clinical and neuropathological features. In the most studied disorders, we also present what is known about underlying pathomechanisms, and compare them with their human counterparts. The purpose of this review is to rekindle interest in this group of diseases and to encourage veterinary researchers to investigate molecular mechanisms by taking advantage of current diagnostic tools.
The classical prion diseases (e.g. scrapie of sheep and goats and bovine spongiform encephalopathy of cattle) are characterized by the accumulation of abnormal forms of the prion protein (PrP), ...usually recognized by their relative resistance to proteolysis compared with the physiological cellular forms of PrP. However, novel prion diseases have been detected in sheep, cattle and man, in which the abnormal PrP has less resistance to proteolysis than identified previously. These more subtle differences between abnormal and normal forms of PrP can be problematic in routine diagnostic tests and raise questions in respect of the range of PrP disorders. Abnormal accumulations of PrP in atypical and classical prion diseases can be recognized by immunohistochemistry. To determine whether altered PrP expression or trafficking might occur in nosological entities not previously connected with prion disease, the brains of sheep affected with diverse neurological conditions were examined for evidence of altered PrP labelling. Such altered immunolabelling was detected in association with either basic lesions or specific diseases. Some reactive glial cells and degenerate neurons found in several different recognized disorders and non-specific inflammatory processes were associated with abnormal PrP labelling, which was absent from brains of healthy, age-matched sheep. The results agree with previous indications that normal PrP function may be linked with the oxidative stress response, but the data also suggest that PrP functions are more extensive than simple protective responses against stress insults.
Background: It is generally believed that after oral exposure to transmissible spongiform encephalopathy (TSE) agents, neuroinvasion occurs via the enteric nervous system (ENS) and the autonomic ...nervous system. As a result, the dorsal motor nucleus of the vagus nerve is the initial point of disease‐associated prion protein (PrPd) accumulation in the brain. Hypothesis and aim: If direct ENS invasion following oral infection results in an early and specific brain targeting for PrPd accumulation, such topographical distribution could be different when other routes of infection were used, highlighting distinct routes for neuroinvasion. Methods: An immunohistochemical study has been conducted on the brain of 67 preclinically infected sheep exposed to natural scrapie or to experimental TSE infection by various routes. Results: Initial PrPd accumulation consistently occurred in the dorsal motor nucleus of the vagus nerve followed by the hypothalamus, regardless of the breed of sheep, PrP genotype, TSE source and, notably, route of infection; these factors did not appear to affect the topographical progression of PrPd deposition in the brain either. Moreover, the early and consistent appearance of PrPd aggregates in the circumventricular organs, where the blood–brain barrier is absent, suggests that these organs can provide a portal for entry of prions when infectivity is present in blood. Conclusions: The haematogenous route, therefore, can represent a parallel or alternative pathway of neuroinvasion to ascending infection via the ENS/autonomic nervous system.
Blood transfusion practices have resulted in iatrogenic cases of variant Creutzfeldt–Jakob disease (vCJD) and it is known that sheep blood is also infectious in the pre-clinical stages of natural ...scrapie and experimentally induced bovine spongiform encephalopathy (BSE). Further investigations have also shown that the pathological phenotype of sheep BSE and human vCJD is maintained after blood transfusion. The present study describes the pathological phenotype, in terms of accumulation of the disease-associated prion protein in brain and lymphoreticular tissues, in sheep receiving blood from donors infected with natural scrapie. The immunohistochemical examinations undertaken showed a degree of phenotypic variability within and between scrapie donors and recipients, which might be attributable to the presence of more than one scrapie strain amongst the donor sheep or to a host adaptation process, or to the interaction of both, rather than to the influence of the route of infection.
We investigated the relationship between leaf shape and leaf hydraulic resistance in a set of broadleaf Quercus tree species (Q. cerris, Q. frainetto, Q. petraea, Q. pyrenaica, Q. robur, Q. rubra, Q. ...velutina). Seedlings of all the studied species were grown under uniform environmental conditions. A new high-pressure flowmeter was designed to measure leaf-blade hydraulic resistance. Leaf shape was characterised by the complexity of leaf outline which was regarded as an estimate of leaf lobation. This was done using the box-counting fractal dimension of the leaf silhouette. Leaf hydraulic resistance was negatively related to leaf lobation. It is suggested that the lower hydraulic resistance in deeply lobed leaves may constitute a mechanism for improving water balance under dry atmospheric conditions.PUBLICATION ABSTRACT
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