Canadian journal of comparative medicine and veterinary science最新文献

Contents of the rumen, abomasum, ileum, and colon of 100 fattened cattle were examined for the presence of Cl. Perfringens. Liquid medium iniculated with each sample of gut content was tested for the presence of toxins of Cl. Perfringens. Identification of Cl. Perfringens was based on atmospheric requirements for growth, colonial morphology, and stormy fermentation in litmus milk. Identification of toxins was based on neutralization tests in guinea pigs and mice.Cl. Perfringens was isolated from 202 of 399 samples. In 105 additional cultures, colonies characteristic of Cl. Perfringens were present but could not be isolated in pure culture.Cl. Perfringens type D toxin was identified in only one culture, which was inoculated with ileum contents. Type A toxin was identified in eight of the 24 samples from the one lot of samples in which no type A antitoxin was used. There were no identifications of toxigenic types B, C, or E. The results indicate that an isolation from necropsy specimens of untyped Cl. Perfringens or type A Cl. Perfringens is in itself of little significance. The infrequency of occurrence of the other toxigenic types in this survey of healthy cattle indicates that recovery of these types from necropsy specimens may be of more significance in determining the cause of death.

The numbers of plaques produced by foot-and-mouth disease virus in primary cultures of calf kidney cells conditioned to 24, 30, and 37 C were essentially the same if virus was absorbed at 37 C. Adsorption was as effective at 30 as at 37 C in cultures conditioned to the respective temperature, but 24 C was less effective under this condition. However, when the adsorption temperature for cultures conditioned to 37 C was decreased to 30 or 24 C, fewer plaques were produced than in cultures conditioned to and maintained at the lower temperatures during absorption. Comparison of the number of plaques produced in cultures overlaid with nutrient agar containing from 0.5 to 10% bovine serum revealed no difference in relation to serum concentration. However, plaque size was related directly to the concentration of serum in the overlay.

The results of bovine herpesvirus (IBR-IPV) neutralization tests conducted on the sera of 463 animals with a prior history of undiagnosed abortion and 331 control animals with no history of abortion are reported. One hundred and thirty-one (28.3 per cent) of the aborting and 105 (31.7 per cent) of the control animals, were found to harbour antibody to this virus. No significant seasonal or gestational incidence could be determined but some variation in the annual incidence was apparent. On the basis of these results it appears unlikely that this virus is responsible for a significant proportion of the undiagnosed cases of bovine abortion in Quebec and Ontario, where the animals tested were located. The problems involved in substantiating a diagnosis of abortion due to bovine herpesvirus are briefly discussed.

The paper describes the changes in P, QRS and T vector orientations in the H plane in the aberrant beats in cases of partial atrioventricular block and premature atrial and ventricular systoles. The sites of possible atrial ectopic foci are discussed in relation to the anatomy of the atrial chambers and the orientation of the P vectors associated with atrial ectopic beats.

Gross and microscopic lesions observed in bovine and porcine hemorrhagic septicemia, and in bovine Pasteurella multocida endotoxemia are described. Widely distributed hemorrhages, edema, and general hyperemia were the most obvious tissue changes observed in the infected calves. Pneumonia was a constant lesion. Aerosol exposure produced a multiple focal fibrinosuppurative pneumonia, while intranasal and intramuscular inoculation resulted in generalized interstitial pneumonia. A slight lymphadenitis and degenerative changes in hepatic and renal parenchymal cells were also observed. The predominant lesions observed in infected pigs were a diffuse, extensive, fibrinous pneumonia and fibrinous polyserositis. Edema and general hyperemia were observed, but the widespread hemorrhages which occurred in the calves were not present. Acute lymphadenitis and renal tubule vacuolar degeneration were observed. A slight amount of cloudy swelling and focal areas of necrosis were found in the liver. Lesions in a calf that died following administration of Past. multocida endotoxin were widely distributed hemorrhages, edema, and general hyperemia. These lesions were especially evident in the lungs, and indicated widespread vascular alteration.

An acute respiratory disease in a colony of Wistar-derived rats is described. The infection, due to Diplococcus pneumoniae type 16, has apparently not been described previously in the rat. Rigid sanitary measures and treatment with penicillin were effective in controlling the disease.

The paper describes observations on the distributions of the P, QRS and T cardiac vectors in the horizontal plane, comparing healthy horses with those with arrhythmia and cardiac murmurs. Deviation of the T vector from the normal range appeared to occur most commonly in association with cardiac murmurs, particularly those involving the semilunar valves and aorta.

Histoplasmosis naturally occurring in laboratory guinea pigs is described in its clinical, necropsy, histological and mycological aspects.The animals if adult show a chronic disease with progressive emaciation and lameness of the hind legs. The young below three months of age died in 2 to 4 weeks presenting ruffled fur, great dorsal curvature and sometimes closed eyelids and catarrhal conjunctivitis. At necropsy the principal lesions were ulcerative gastritis, hemorrhagic and catarrhal enteritis, enlarged spleen and mesenteric lymph nodes. Sometimes the liver, lungs, mediastinal lymph nodes and other organs showed lesions. Histological and mycological demonstration of the fungus completed the diagnosis and the surviving animals were burned and sanitation measures instituted. Histological evidence of histoplasmosis in a cow's lung from the area from which the grass was obtained for the feeding of the guinea pigs suggests an epidemiological link. Efforts will be made to isolate and demonstrate H. capsulatum in wild animals on the same area.

A severe gastroenteritis affected Ontario pigs in the Spring of 1964 and again in 1966. The mortality of pigs less than a week of age was 100%, in older pigs there were few deaths although morbidity in these pigs approximated 100%. Viruses were isolated from the brains, intestines, and intestinal lymph nodes of baby pigs. One of these isolates, given by mouth to two colostrum deprived piglets, induced a severe enteritis 36 hours after administration and both of the piglets died 24 hours later. The characteristics of the disease and the virus bear a striking resemblance to transmissible gastroenteritis as seen in the United States of America and the United Kingdom.