Pathological studies on cerebral amyloid angiopathy, senile plaques and amyloid deposition in visceral organs in aged dogs.

The relationship between cerebral lesions such as amyloid angiopathy or senile plaques and amyloid deposition in the visceral organs were studied in 90 autopsy cases of dogs, 0 to 19-year-old. Cerebral amyloid angiopathy was detected in 28 aged dogs (mean age: 13.7-year-old) and was found mostly in or around the wall of cerebral meningeal arterioles and capillaries of the neocortex. That condition was often accompanied by cerebral hemorrhage in dogs more than 9 years of age. Senile plaques were detected in the neocortex of the brain of 12 dogs (mean age: 13.2-year-old) and classified into 3 subtypes, i.e., "diffuse plaque", "primitive plaque" and "classical plaque". Among those 3 subtypes of senile plaques, amyloid containing plaques were small in number. In the visceral organs of dogs with cerebral amyloid angiopathy, amyloid deposition was found in the vascular walls or connective tissues of small intestines at a high frequency and sometimes in the vascular walls of the heart, lung, liver and thyroid gland as well as in atrioventricular valves. Amyloid in both cerebral and visceral organs was congophilic and showed green birefringence under poralized light even after potassium permanganate oxidation.     

A case study of rabies diagnosis from formalin-fixed brain material

Rabies is caused by several Lyssavirus species, a group of negative sense RNA viruses. Although rabies is preventable, it is often neglected particularly in developing countries in the face of many competing public and veterinary health priorities. Epidemiological information based on laboratory-based surveillance data is critical to adequately strategise control and prevention plans. In this regard the fluorescent antibody test for rabies virus antigen in brain tissues is still considered the basic requirement for laboratory confirmation of animal cases. Occasionally brain tissues from suspected rabid animals are still submitted in formalin, although this has been discouraged for a number of years. Immunohistochemical testing or a modified fluorescent antibody technique can be performed on such samples. However, this method is cumbersome and cannot distinguish between different Lyssavirus species. Owing to RNA degradation in formalin-fixed tissues, conventional RT-PCR methodologies have also been proven to be unreliable. This report is concerned with a rabies case in a domestic dog from an area in South Africa where rabies is not common. Typing of the virus involved was therefore important, but the only available sample was submitted as a formalin-fixed specimen. A real-time RT-PCR method was therefore applied and it was possible to confirm rabies and obtain phylogenetic information that indicated a close relationship between this virus and the canid rabies virus variants from another province (KwaZulu-Natal) in South Africa.     

Pathological anxiety in animals

Selective breeding programmes in domestic and laboratory animals generally focus on physiological and/or anatomical characteristics. However, selection may have an (unintended) impact on other characteristics and may lead to dysfunctional behaviour that can affect biological functioning and, as a consequence, compromise welfare and quality of life. In this review it is proposed that various behavioural dysfunctions in animals are due to pathological anxiety. Although several approaches have been undertaken to specify the diagnostic criteria of pathological anxiety as a behavioural disorder in animals, the causal aetiology largely remains unknown. This is mainly due to the fact that integrated concepts, combining the behavioural syndrome and (neuro-) physiological processes, are widely lacking. Moreover, even the term anxiety itself represents a poorly defined concept or category. A definition is suggested and the potential causes of pathological anxiety are explored with a plea for developing adequate diagnostic tools and therapies to fight pathological anxiety in animals based on insight from scientific research.     

Pathological characterization of TgElk mice injected with brain homogenate from elk with chronic wasting disease

Chronic wasting disease (CWD) is classified as a transmissible spongiform encephalopathy or prion disease that affects cervids. CWD has been reported in 15 US states, two Canadian provinces, and in imported elk on several farms in Korea. This study was conducted to examine the molecular biological and pathogenic characteristics of a CWD-associated prion isolated in Korea. The epidemiological origin of this pathogen was also determined. Homozygous TgElk mice were infected with a CWD-affected elk brain pool prepared from the brain of an imported Canadian elk. We measured the incubation time of the pathogen, neuropathological changes by immunohistochemical staining, the pattern(s) of scrapie prion protein (PrP^Sc) deposition, and PrP^Sc protein profiles by Western blotting. We found that TgElk mice infected with brain homogenate from the elk suffering from CWD showed incubation times, vacuolar degeneration, and PrP^Sc accumulation similar to those previously reported in the literature. Our results suggest that homozygous TgElk mice efficiently transmit CWD with short incubation times and that this animal can serve a valuable research model and reliable in vivo diagnostic tool.     

Disseminated oesophagostomiasis in the rhesus monkey.

Disseminated oesophagostomiasis was diagnosed at necropsy of 5 rhesus monkeys (Macaca mulatta). Nodular lesions were in visceral organs as well as in the colon and mesentery. Lesions varied greatly with respect to degree of organ involvement and damage due to parasite invasion. In 2 monkeys, nodular lesions were in the colon, mesentery, liver, kidneys, abdominal wall, urinary bladder, and uterus; in 1 of these 2 monkeys, a nodular lesion inhabited by a parasite was in a lung. The ectopic nodules in the less severely affected monkeys were scattered in the liver, kidneys, and abdominal wall.