Canadian journal of comparative medicine : Revue canadienne de medecine comparee最新文献

3-Acetyldeoxynivalenol was incorporated into a semisynthetic diet at levels of 2.5, 5, 10 or 20 ppm and fed to mice for up to 48 days. Body weights and feed consumption were determined, and blood samples for hematological evaluation were taken. Selected tissues were examined microscopically and the humoral immune response was assessed using the Jerne plaque assay. 3-Acetyldeoxynivalenol caused a dose-related depressed feed consumption within the first seven days and reduced body weight until day 14 when fed at levels up to 10 ppm. When fed at a level of 20 ppm, an initial depression in body weight gain and a general malaise were followed by a return to normal. At necropsy, no macroscopic or microscopic lesions could be found. The immune response was not significantly affected after seven or 14 days, but at 21 days, a dose-dependent enhanced response was observed. The findings indicate that, after an initial period of reduced feed intake, animals are apparently able to overcome the toxic effects of 3-acetyldeoxynivalenol.

During serological screening of a closed SPF-herd free of pleuropneumonia, more than half of the pigs were positive for complement-fixing antibodies to Haemophilus pleuropneumoniae. Actinobacillus bacteria closely related to A. suis were isolated from tonsillar tissue of 14 out of 20 slaughtered pigs submitted for pathological and bacteriological evaluation. None of the pigs had evidence of respiratory disease. Two pigs inoculated endobronchially with a selected Actinobacillus strain developed mild focal pneumonia and complement-fixing antibodies cross-reacting with H. pleuropneumoniae. Five pigs exposed and vaccinated with the Actinobacillus strain and five pigs spontaneously infected with the strain also developed complement-fixing antibodies against H. pleuropneumoniae and appeared to be less susceptible to experimental Haemophilus pleuropneumonia than pigs not exposed to the Actinobacillus infection. The agglutination test applied on serum treated with 2-mercaptoethanol detected antibodies against H. pleuropneumoniae serotype 5 but not against serotype 1 in pigs exposed to the Actinobacillus strain. Antibodies reactive with the Actinobacillus strain were also found in pigs hyperimmunized against H. pleuropneumoniae serotypes 1-5 in 2-mercaptoethanol tube agglutination test and rabbits hyperimmunized against serotypes 1,2 and 7, and strain 73567 in the immunodiffusion test. Conversely rabbits immunized against the Actinobacillus strain had antibodies against H. pleuropneumoniae serotypes 1, 3, 4, 5 and 6. It is concluded that pigs infected with Actinobacillus organisms may become false positive reactors against H. pleuropneumoniae.

Euthanasia of unwanted or sick animals should always be done in a humane manner. This study involving two groups of 12 dogs evaluated a two step method of euthanasia using first acepromazine or pentazocine then inhalation of carbon monoxide. During the experiment, behavioral reactions (anxiety, agitation, vocalization and sphincter relaxation) and physiological parameters (electro-encephalogram, electrocardiogram, arterial blood pressure, respiratory and heart rates and serum cortisol) were monitored. The results showed that both drugs modified many behavioral reactions and physiological changes associated with administration of carbon monoxide. Acepromazine and pentazocine reduced by 25% and 20% respectively the number of dogs that showed vocalization and agitation. In acepromazine premedicated dogs, the duration of these signs was significantly diminished and sphincter relaxation did not occur in more than 50% of cases. Furthermore, with the use of acepromazine, no significant peaks or drastic drops were noticed in the heart and respiratory rates and in the arterial blood pressure. These manifestations are usually related to stress. In light of these results, it is recommended to premedicate dogs with acepromazine before submitting them to euthanasia by carbon monoxide inhalation.

Pathological changes in respiratory tracts were studied in 30 calves following exposure to aerosols of Pasteurella multocida or to bovine herpesvirus 1 and P. multocida. Two groups of five calves were exposed to aerosols of one of two types of P. multocida only, which produced lobar pneumonia in one calf of each group. Another five groups of four calves were exposed to aerosols of bovine herpesvirus 1 and four to seven days later to one of the two types or one sub-type of P. multocida. Extensive necropurulent lesions were produced throughout the respiratory tract with each type of P. multocida in all four calves in three groups but none in the remaining two groups. The pathological changes differed from those produced following similar exposures to bovine herpesvirus 1 and P. haemolytica, in that the exudate in air passages and alveoli was more purulent and streaming (oat) cells and large mononuclear eosinophilic granulocytes were absent. This is the first report of experimental respiratory disease in cattle as a result of aerosol exposure to P. multocida alone or in combination with bovine herpesvirus 1.

The purpose of this research was to determine the effect of social stress on the susceptibility of chickens and swine to Staphylococcus aureus infection. Chickens were housed under four levels of social stress. Weaned pigs remained with their litter or were housed separately. One day after some birds were placed in the high stressed environments all were challenged intravenously with S. aureus. Susceptibility was characterized by joint infection in swine and reduced weight gain in chickens. Chickens which were moved into the high stressed environments before challenge lost weight while the controls gained weight (P less than 0.001). During the three days postchallenge the most severely stressed chickens lost less than half as much body weight as did the least stressed (P less than 0.001). During the post-challenge period chickens selected for high corticosterone response in a high social stress gained weight while chickens selected for a low corticosterone response in a low stress environment lost weight (P less than 0.0001). Swine housed under a reduced level of stress (social) were more susceptible to S. aureus than those kept under higher levels of stress (P = 0.0001).

Street rabies virus isolated from 51 specimens from Ontario, Quebec, Manitoba and the Northwest Territories have been typed by a panel of 36 antinucleocapsid monoclonal antibodies. Three main groups were found. The first group comprised those terrestrial mammals originating in Ontario, Quebec and the Northwest Territories. The second group was found in terrestrial mammals from Manitoba. The third heterogenous group was made up of bats from Ontario.

Tissue damage caused by six different adjuvants incorporated in a Haemophilus pleuropneumoniae vaccine was compared in swine. The adjuvants compared were four mineral oil compounds, one peanut oil compound and aluminum hydroxide. Inoculations were given in the neck, quadriceps and semitendinosus muscles. The mineral oil adjuvants were highly irritant and caused extensive areas of granulomatous inflammation that were present at eight weeks after injection. The aluminum hydroxide produced smaller lesions that also persisted for eight weeks. Only the peanut oil adjuvant did not produce significant lesions at the site of injection. At two and four weeks, but not at eight weeks postinoculation, lesions in the quadriceps and semitendinosus muscles were approximately twice as extensive as those in the muscles of the neck.

The liver copper concentration of the bovine fetus and the hepatic and plasma copper concentrations of its dam during the first trimester of pregnancy were studied. The effect of the dam's dietary copper intake, age, sire breed and stage of pregnancy on her copper status and that of her fetus was also investigated. Simmental sired heifers had the lowest plasma copper concentration. The younger cows (two, three and four years) had significantly lower liver copper concentration than the older cows (six and seven years). The bovine fetal liver copper concentration was approximately 3.1 mmol/g DM and was not affected by dam's age, breed, stage of pregnancy, or copper status.