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

Several properties of the adhesins of eight isolates of Moraxella bovis recovered from cattle suffering from infectious keratoconjunctivitis, were studied. Adhesions were detected through autoagglutination in saline and hemagglutination. Autoagglutinating strains agglutinated red blood cells of the chicken, rabbit, sheep and swine, but not those of the guinea pig. The adhesins were not inhibited by D-mannose or D-galactose and resisted heating at 100 degrees C for 15 minutes. Magnesium chloride at a final concentration of 10% inhibited autoagglutination and hemagglutination. The value of the hemagglutination test for monitoring synthesis of fimbriae by M. bovis, is discussed.

The standardization of pig neutrophil chemotaxis under agarose is described. The mean chemotactic index for pig neutrophils from six pigs measured over four days was 1.29. Comparative studies of human and pig neutrophil chemotaxis under agarose revealed a lower chemotactic index for pig neutrophils (mean of 1.18) compared to human neutrophils (mean of 2.43). The results suggest that this is due to differences intrinsic to human and pig neutrophils. In vitro pig neutrophil chemotaxis was measured in normal pigs and in pigs following experimental Salmonella typhimurium infection. Significant alterations in chemotaxis were not evident one and seven days postinfection.

Dogs were classified into a number of disease categories according to hematological, cytological and serochemical changes. Aspiration and core bone marrow biopsies were examined in 128 dogs in the various disease categories and compared to marrow samples in 36 dogs which appeared clinically normal. Differential cell counts on bone marrow smears were examined in relation to the blood variables in all animals. Blood and bone marrow data (group means) were compared among the normal and disease groups. Anemia, responsive and poorly responsive was the most frequent blood abnormality. Most dogs in the thrombocytopenia group had increased numbers of megakaryocytes in the marrow but two dogs had a marked decrease. The frequency of serious alteration of marrow production of the erythroid, myeloid and megakaryocytic series was less than anticipated. Marrow hemopoiesis was not significantly compromised in dogs with lymphoma or in dogs with other types of cancer. Bone marrow examination was necessary for the diagnosis of myelofibrosis and pancytopenia and was very helpful in the groups with insufficient change in the blood to permit a definitive diagnosis to be made. The myeloid-erythroid ratio was a useful indicator of marrow response while the erythroid maturation index and the myeloid maturation index were useful for identification of altered patterns of maturation (ineffective hemopoiesis). The reticulocyte response in absolute numbers is the most efficient and clinically relevant measure of erythroid response.

During routine bacteriological examination of pneumonic calf lungs it was experienced that many Pasteurella multocida-like isolates had a fermentation pattern different from what is generally accepted for P. multocida sensu stricto. Forty-one out of 50 strains selected for further investigation were phenotypically related and formed a group of indole-, mannitol-and sorbitol-negative P. multocida-like strains, which was tentatively designated taxon 13. Deoxyribonucleic acid/deoxyribonucleic acid hybridizations including both ornithine positive and ornithine negative strains of taxon 13 allowed the classification of the former as P. multocida biovar 6 and the latter as V factor independent strains of Haemophilus avium.

The virulence of strains of Haemophilus pleuropneumoniae serotype 1, 2, 3, 7 and strains of the "minor-group" and Haemophilus parasuis were compared by inoculating specific pathogen-free pigs into the lower airways with specified doses of bacteria. Haemophilus pleuropneumoniae, strain W, serotype 1, given in 1 X 10(8) colony-forming units, produced a lethal acute pleuropneumonia in four pigs. Nonlethal localized pulmonary necrosis was induced in four groups of two pigs given 1 X 10(7), 1 X 10(6), 1 X 10(5) and 1 X 10(4) respectively of the same strain. Two groups of four pigs developed chronic lesions when inoculated with 1 X 10(7) colony-forming units of H. pleuropneumoniae, strain Shope 4074, serotype 1 and 1 X 10(7) colony-forming units of H. pleuropneumoniae, strain WF83, serotype 7, respectively. Of 20 pigs given 1 X 10(8) colony-forming units of strain 1536, serotype 2, two died of acute pleuropneumonia and 18 had lesions of pulmonary necrosis or abscessation and pleuritis. A dose of 4 X 10(9) colony-forming units of strain BC181, serotype 3, induced pulmonary necrosis similar to the lesions in pigs given 10(7) colony-forming units or less of strain W, serotype 1, suggesting that the serotype 3 strain is less virulent. No clinical signs, but focal areas of pulmonary fibrosis and pleural adhesions were induced in four pigs inoculated with 4 X 10(9) colony-forming units of the "minor-group" strain 7ATS. Similarly, four pigs inoculated with "minor-group" strain 33PN did not show clinical signs, but had focal necrotic and fibrotic pulmonary lesions and pleural adhesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Fourteen strains of Escherichia coli of serogroups characteristic of porcine class 2 enterotoxigenic E. coli isolated from pigs or calves were selected for genetic studies. The strains were examined for their ability to cotransfer a number of plasmid-mediated properties during conjugation with E. coli K-12. These properties were antibiotic resistance, and the production of heat-stable enterotoxin, the K99 antigen and colicin and the ability to ferment raffinose. Distinction was made between the two types of heat-stable enterotoxin, STa and STb. All 14 strains were antibiotic resistant and 11 of them cotransferred antibiotic resistance and heat-stable enterotoxin. One strain which transferred heat-stable enterotoxin also transferred the raffinose gene. Among six K99-positive strains which transferred heat-stable enterotoxin, five always cotransferred K99. Three strains had 100% cotransfer of colicin as well as heat-stable enterotoxin and K99. Drug resistance determinants were cotransferred at high frequency with heat-stable enterotoxin for six of eight multiple drug resistant enterotoxigenic E. coli. A 100% cotransfer of combinations of heat-stable enterotoxin, K99, colicin and antibiotic resistance was often associated with a single plasmid band on agarose gel electrophoresis. For some strains, the genes for STa and STb were on the same plasmid and for others they were on separate plasmids. The enterotoxin plasmids ranged in size from 5.2 to 85 Mdal. Heterogeneity in molecular size occurred among enterotoxin plasmids in E. coli of the same serogroup and recovered from the same animal host species.

Double outlet right ventricle, a rare congenital heart anomaly of either animals or man, was diagnosed in a three day old Brangus heifer. The clinical course was brief, consisting of terminal recumbency, dyspnea and cyanosis. Upon necropsy, the heart was enlarged as a result of marked dilatation of the right atrium and the right ventricle. The aorta arose from the right ventricle while the left ventricle ended blindly near the ventral cusp of the left atrioventricular valve. The wall of the left ventricle was thickened, reducing the ventricular lumen.

The infectivity of Trichinella spiralis nativa isolates from widely separated geographic areas of Canada was determined by feeding infected musculature to swine, laboratory rats and carnivores (cats, foxes, ferrets). Low infectivity for swine and rats and high infectivity for carnivores were observed. Light infections were established in four of 16 swine examined between 25 and 53 days postinfection. Feeding of infected porcine musculature to ferrets demonstrated that Trichinella spiralis nativa can be passaged through swine even though the infectivity rate is low.

A field trial was designed to determine the efficacy of a combination rotavirus-coronavirus/Escherichia coli vaccine on dairy farms in southwestern Ontario. In Part A of the trial, 321 cows on 15 farms were randomly assigned to either vaccination or placebo groups. On eight farms, 50% of the dams were vaccinated, while on the other seven farms, 80% of the dams were vaccinated. In Part B of the trial, 26 farms were randomly assigned to either a total vaccination program or to no vaccination program. Mortality, disease occurrence and weight gains were recorded on all calves for the first two weeks of life. In Part A, 23.5% of all calves were treated in the first two weeks of life, 20.9% were treated specifically for scours and 3.6% of live-born calves died. Enteropathogenic E. coli was identified on 13 of the 15 farms, rotavirus on 11 and coronavirus on ten. At least one of the three potential pathogens was found on every farm. There were no significant differences between calves from placebo-treated and vaccine-treated dams with regard to the proportion treated for all diseases, or for scours, or the proportion which died. Neither were there differences in days to first treatment for all diseases (seven days on average), days to first scour (6.7 days), duration of treatments (3.9 days for all diseases, 3.7 days for scours), or estimated weight gains (0.5 kg/day to 14 days). These results were not altered when the presence or absence of enteropathogenic E. coli, rotavirus or coronavirus on the premises was accounted for.(ABSTRACT TRUNCATED AT 250 WORDS)

A viral agent was isolated from the fetal liver of an aborted equine fetus. The isolate hemagglutinated red blood cells from guinea pig, rhesus monkey and rooster. By hemagglutination inhibition tests, the isolate was shown to be antigenically distinct from parvoviruses of bovine and canine origin. Specific hemagglutination inhibiting antibody against the viral isolate was exhibited by 26 of 136 horse sera tested. The isolated virus showed properties compatible with those of an autonomous parvovirus including size, morphology, stability to ether treatment and heating to 56 degrees C, the presence of a 5300 base DNA genome, characteristic protein composition and density (1.405 g/mL). The virus was classified as an equine parvovirus.