Canadian journal of comparative medicine and veterinary science最新文献

Theoretical consideration has been given in two horses to the properties of the electric field created by the equine heart acting as a simple electric generator. The principles of the vectorial theory have been applied to test the validity of application of the dipole concept. The cardiac electric forces, althrough complex in the immediate region of the heart, appear at the body surface in a similar form to those arising from a relatively immobile, single equivalent dipole. The potential value of the technique of vectorcardiography in cardiological investigations is briefly discussed.

A strain of haemagglutinating virus isolated by Walker and Bannister in 1953 and identified by them as "Filterable Agent" of ducks has been examined. The evidence suggests that although belonging to the Myxovirus Influenza Type A group, it possesses specific strain properties.

Of 345 market chicken carcasses received directly from selected processing plants across Canada, six yielded salmonellae. One of the plants submitted 122 carcasses none of which yielded these organisms. A second plant had one Salmonella-contaminated carcass among 20 which were examined. Each of these two plants was subected to detailed bacteriological examinations on four occasions. In these detailed examinations a total of 175 samples or specimens for culture were taken from a variety of surfaces including vent areas of carcasses, operators' hands, equipment surfaces and from water in tanks of iced birds. Twenty-five (14 per cent) of the cultures yielded salmonellae and all but one of these were either S. oranienburg or S. infantis. Isolations were made during five of the eight series of examinations. The evidence indicated that Salmonella-infected flocks were frequently slaughtered and that Salmonella contamination could become widespread in the plant during processing. The organisms are apparently eliminated from all but a small percentage of the carcasses during processing but opportunities exist for recontamination during subsequent handling.

Crystal violet has been observed to cause fatal pulmonary alterations in dogs. To further evaluate this toxicity and the toxicity of methyl violet, 12 dogs and 2 calves were given 1 percent aqueous solutions of the dyes intravenously. Both dyes caused the formation of numerous dye protein emboli which lodged in the lungs producing thrombosis and infarction. A 1 per cent solution of the dyes caused precipitate formation when added to bovine serum or heparinized plasma IN VITRO. Serum proteins in general were decreased as determined by paper electrophoresis of serumcrystal violet supernatants. These dyes could be used effectively in studying the pathogenesis of certain pulmonary lesions, especially emphysema and alveolar epithelial hyperplasia.

Two methods of semen collection were attempted on ten untrained dogs of several breeds. Manual manipulation as described proved most reliable for untrained dogs. Electro-ejaculation was attempted unsucessfully with twelve additional dogs.Two methods of insemination were compared. Equipment found most satisfactory is described and a modification suggested.

A bovine strain of myxovirus parainfluenza-3 (MP3) virus, designated S virus, was isolated from lung tissue collected from cattle with respiratory illness in 1963. The virus agglutinates mammalian and avian erythrocytes, and is sensitive to ether, sodium desoxycholate and trypsin. It grows in primary calf kidney, buffalo kidney, dog kidney, camel kidney and MS cell cultures. The S virus forms well-defined plaques in buffalo and calf kidney cells on the 5th or 6th day after inoculation. Examination of cell cultures following inoculation with S virus revealed giant cell formation, and introcytoplasmic and intranuclear inclusions. At 37 degrees C the virus titer dropped from 10(10.4) to 10(2.6) in 3 days. Virus was completely inactivated at 56 degrees C within 15 minutes. Growth-curve studies in tissue culture monolayer cells revealed a latent period of 10 hours. The intracellular virus titer was slightly lower than that of extracellular virus. The isolate was identified as MP3 virus by serum neutralization and hemagglutination-inhibition tests. Antibodies (HI) to S virus were shown to be present in a significant proportion of Egyptian cattle. The epidemiological significance of MP3 (bovine strain) virus in U.A.R. is discussed.

An improved microscopic method for counting leucocytes in milk has been developed, which results in acceptable levels of reproducibility. To overcome the lack of uniform cell distribution within a film a stratified sampling of the total film area is examined, which prevents the counting of any one area twice. The mean between-film coefficient of variation (S.D./x X 100) for all milk samples examined which contained more than 350,000 leucocytes/ml. was less than 10%.