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Biomedical subjects

W D Yates

Publications and source records attributed to W D Yates.

34 records · Page 2Linked to original sources
PubMed1983

Viral-bacterial pneumonia in calves: duration of the interaction between bovine herpesvirus 1 and Pasteurella haemolytica.

Sixteen six to eight month old beef calves were exposed individually to a five minute aerosol of bovine herpesvirus 1, isolate 108. Aerosol exposure to Pasteurella haemolytica (biotype A, serotype 1) was administered individually for five minutes at either four, ten, 20 or 30 days after the virus. Fibrinous pneumonia and pleuritis occurred in all four groups but were most extensive and severe in those exposed to the virus and bacterium four days apart (the positive controls). Fibrinous pneumonia was associated with persistence of bovine herpesvirus 1 in the respiratory tract despite resolution of virus-induced necrotic lesions of the respiratory mucosa. The results presented here suggest that, although the severity of viral-bacterial synergism may be influenced by virus-induced morphological changes, the continued presence of viral antigens after the resolution of respiratory mucosal lesions may continue to exert some effect on host defenses and disease processes.

Animals↗
PubMed1983

The relationship of serology and nasal microbiology to pulmonary lesions in feedlot cattle.

A group of 62 beef calves, born and raised in an institutional herd, were transferred at nine months of age to a commercial feedlot where they remained until slaughter seven months later. Clinical, immunological and microbiological monitoring was carried out during this period. No serious clinical illness occurred. One hundred percent seroconversion to bovine virus diarrhea virus took place after introduction of the calves into the feedlot as well as almost complete (59/62) seroconversion to bovine herpesvirus 1, a proportion of which could be related to a single vaccination. Significant increases in recoveries of Mycoplasma spp. from nasal swabs also occurred in the feedlot. At slaughter, the lungs of all animals were recovered and examined for pathological lesions: 23 were completely normal and 39 showed minor histological changes chiefly characterized by areas of lobular to sublobular atelectasis. For this group of calves, no relationship was found between the presence of potential pathogens in nasal mucus and the occurrence of lesions in the lung. The serological results are discussed in terms of vaccinations and other known events that occurred during the study period.

Animals↗
PubMed1983

Effect of bacterial dose on pneumonia induced by aerosol exposure of calves to bovine herpesvirus-1 and Pasteurella haemolytica.

Sixteen crossbred Hereford range calves were used to study the effects of Pasteurella haemolytica aerosols of various concentrations administered 4 days after they were exposed to a uniform aerosol of bovine herpesvirus-1 (BHV-1). All calves were given BHV-1 on day 0. On day 4, groups of 4 calves each were exposed to aerosols of P haemolytica generated from suspensions with the following concentrations: high (10(8)/ml)--group 1, moderate (10(5)/ml)--group 2, low (10(2)/ml)--group 3, or none (control)--group 4. All calves developed clinical signs of respiratory infectious bovine rhinotracheitis. Those in group 4 (controls) and group 3 (low bacterial concentration exposure) were near complete recovery by day 8. At necropsy, most calves in all groups had diphtheritic inflammation of the mucosal surfaces of the upper and lower respiratory tracts and lobular atelectasis of the lung parenchyma. Three of the group 2 calves (exposed to the moderate concentration of P haemolytica) and all group 1 calves became severely ill with fibrinous pneumonia; 3 in the latter group died by day 8. For the conditions of this experiment, the 50% lethal dose was 1 X 10(7.1) bacteria/ml of suspension from which the aerosol was generated and 1 X 10(5.1) P haemolytica inhaled/calf. The 50% effective dose for fibrinous pneumonia was 1 X 10(4.1) P haemolytica/ml of suspension and 1 X 10(2.1) bacteria inhaled/calf. The term "inhaled" was used to mean the number of organisms estimated to be taken into the respiratory tract at the level of the nostrils. The results indicated that there is a positive relationship between degree of exposure to P haemolytica and severity of pneumonia in this disease model.

Aerosols↗
PubMed1982

Bovine herpesvirus-1 vaccination against experimental bovine herpesvirus-1 and Pasteurella haemolytica respiratory tract infection: onset of protection.

The onset of protection offered by intranasal vaccination with attenuated bovine herpesvirus-1 (BHV-1) was studied in 18 calves given a virulent BHV-1 aerosol challenge inoculum and an aerosol challenge exposure to Pasteurella haemolytica. Calves challenge exposed with virus 3, 7, 11, 15, or 19 days after vaccination and challenge exposed 4 days later with Pasteurella haemolytica did not develop viral-bacterial pneumonia, whereas 2 of 3 control calves died of fibrinous bronchopneumonia 40 and 60 hours after the bacterial aerosol and the 3rd control calf had similar lesions. All vaccinated and control calves had detectable amounts of interferon at the time of viral challenge exposure. Protection was observed before detection of neutralizing antibodies to BHV-1 in nasal secretions or in serum. Protection was therefore present from day 3 through day 19 after vaccination, but the mechanism could not be explained completely by neutralizing antibody or interferon.

Animals↗
PubMed1982

A review of infectious bovine rhinotracheitis, shipping fever pneumonia and viral-bacterial synergism in respiratory disease of cattle.

Unanswered questions on the etiology and prevention of shipping fever pneumonia have allowed this disease to remain one of the most costly to the North American cattle industry. Research in this area has indirected that while Pasteurella haemolytica and, to a lesser extent, P. multocida are involved in most cases, they seem to require additional factors to help initiate the disease process. Bovine herpes virus 1 has been shown experimentally to be one such factor. This review examines in some detail the topics of infectious bovine rhinotracheitis, shipping fever, and viral-bacterial interactions in the production of respiratory disease in various species. It deals with history, definitions, etiologies, clinical signs and lesions, and considers exposure levels, transmission and various pathogenetic mechanisms that are postulated or known to occur.

Animals↗
PubMed1981

Comparison of Collison and De Vilbiss 65 nebulizers in the generation of aerosols for respiratory disease studies.

An electronic particle counting instrument was used to compare aerosols of minimal essential medium and brain heart infusion broth containing 5% fetal bovine serum generated by Collison and De Vilbiss 65 nebulizers. The median diameter of Collison particles was approximately one half (0.8 micron) that of De Vilbiss particles (1.8 micron) at De Vilbiss settings of 3.5, 5.0, 7.0 or 10.0. The average De Vilbiss particle output per minute at these settings (5.0 X 10(6)) was significantly greater (p less than 0.01) than for the Collison (4.0 X 10(6)). Settings below 3.5 produced erratic total output and particle size. More particles were produced by the De Vilbiss from minimal essential medium than from brain heart infusion broth containing 5% fetal bovine serum at a setting of 2.0, whereas median particle size and total output did not vary appreciably between media at settings of 3.5 or greater. Because of these variations, it is suggested that the output characteristics of nebulizers be specified in reports of experimental respiratory disease studies using aerosols.

Aerosols↗
PubMed1981

Bovine respiratory disease questionnaire.

The purpose of the questionnaire was to gain an insight into the state of the art and to give direction to control measures for, and research into, bovine respiratory disease. Workers with an active interest in bovine respiratory disease were asked to respond. With the approval of the Committee on Large Animal Practice, it was distributed in Canada by the office of the Canadian Veterinary Medical Association to the veterinary colleges, the federal animal diseases research laboratories and the directors of provincial veterinary services for further distribution, and also to the Veterinary Infectious Diseases Organization and Connaught Laboratories.Twenty-six questionnaries were returned and one letter was received in response. Replies were from 13 research scientists (including clinicians), six laboratory diagnosticians, four regulatory workers, three administrators, and one person of unknown specialization.

Animals↗
PubMed1980

Chemoreceptor tumors diagnosed at the Western College of Veterinary Medicine 1967-1979.

Twenty-nine chemoreceptor tumors submitted to the Western College of Veterinary Medicine, Saskatoon, Saskatchewan between 1967 and 1979 were compared with those previously reported. The prevalence was low, with 28 cases occurring in dogs while only one was diagnosed in a cat. Old male dogs and the Boxer, Boston bull terrier and Collie breeds were affected most commonly. The prevalence in Collies (five of 28 dogs) was unexpected but may have been coincidental in this size of sample. The chemoreceptor tumor was often of clinical significance because in two-thirds of the cases it was either the presenting complaint or considered at necropsy to have caused illness or death.

Age Factors↗
PubMed1980

Concurrent bovine virus diarrhea and bovine papular stomatitis infection in a calf.

A case of concurrent infection with the viruses of bovine virus diarrhea and papular stomatitis in a calf is reported. The difficulties posed by such situations are described and the criteria used for diagnosis outlined. The two diseases are reviewed briefly and the possible mechanisms whereby bovine virus diarrhea virus is suspected of facilitating infection by other agents are discussed.

Animals↗
PubMed1979

Proliferative hemorrhagic enteropathy in swine: an outbreak and review of the literature.

An account is given of an acute outbreak of hemorrhagic enteric disease in 34 young adult boars of primarily Yorkshire breeding at a performance testing station in Western Canada. Two of the boars died. A diagnosis of proliferative hemorrhagic enteropathy was made on the basis of clinical signs, gross necropsy and histopathological lesions. Campylobacter-like bacteria were seen in the apical cytoplasm of epithelial cells of the ileal mucosa by Warthin-Faulkner stain on histological sections, but were not isolated on culture. Treatment with several drugs simultaneously was associated with termination of the outbreak, but the therapeutic effect was not controlled by leaving some animals untreated. Reported sequelae, such as porcine intestinal adenomatosis, were not present at necropsy or slaughter of pigs surviving the outbreak, but all were killed no longer than two months after the first case was observed. This outbreak is discussed in the context of previously reported hemorrhagic enteric conditions of pigs.

Anemia↗
PubMed1979

Experimental bovine pneumonic pasteurellosis. II. Genesis and prevention.

Two experiments were conducted. In the first, 16 crossbred Hereford calves were divided into two equal groups. The first group was vaccinated intranasally with a commercial vaccine against bovid herpesvirus 1 and the second group was unvaccinated. The calves were later exposed to an aerosol of bovid herpesvirus 1 (strain 108) for five minutes. Four calves from each group were subjected to transportation and four calves from each group were kept in an environmental chamber for four days. Four days after viral aerosol all calves were exposed to an aerosol of Pasteurella haemolytica and the same subgroups were again transported or held in the chamber for a further four days. The calves that did not die from pneumonia were necropsied ten days after the final day of transport. Pulmonary lesions were present in both vaccinated and control animals but were less extensive in the vaccinated calves. Six of eight vaccinated but none of the eight control calves survived. In the second experiment, eight crossbred Hereford calves were divided into two equal groups. One group was vaccinated with bovid herpesvirus 1 (strain 108) and the other acted as controls. Four weeks later all calves were sequentially exposed to aerosols of bovid herpesvirus 1 (strain 108) and P. haemolytica four days apart. Three of the four controls but none of the vaccinates died from pneumonia. Every lobe of the lungs in all the controls was affected by pneumonia while no pulmonary lesions were found in the vaccinated calves. The differences in efficacy of the modes of vaccination and the possible role of transport stress are discussed.

Animals↗
PubMedDate not supplied

Depletion of penicillin G residues in tissues and injection sites of yearling beef steers dosed with benzathine penicillin G alone or in combination with procaine penicillin G.

The contribution of benzathine penicillin G to residues in tissues and injection sites of yearling beef steers was assessed by treating seven groups of five to seven steers with either benzathine and procaine penicillin G together or benzathine penicillin G alone. Steers were injected with a commercial combination of benzathine and procaine penicillin G according to the Canadian (intramuscular) or United States (subcutaneous) label dosages of 8600 and 8800 IU penicillin G/kg body weight, respectively. They were killed 14 or 30 days after the intramuscular injections, and 30 days after the subcutaneous injections. At the label withdrawal times, Canadian 14 days and United States 30 days, the levels in the injection sites for all of the treatments were 30-60 times above the Canadian and United States' Maximum Residue Limit of 50 micrograms/kg, while liver, kidney and gluteal muscle levels were below the Maximum Residue Limit. Other steers were injected intramuscularly with 24,000 IU benzathine/procaine penicillin G/kg body weight and slaughtered 8, 14 or 50 days after injection. Fifty-day injection site residues were 24 times the Maximum Residue Limit. Another group of steers was injected intramuscularly with benzathine penicillin G alone at 12,000 IU/kg body weight and slaughtered 14 days later. Penicillin G levels in the injection sites were 156 times the Maximum Residue Limit. The persistence of penicillin G residues at the injection sites in all the treatment groups appears to be attributable primarily to benzathine penicillin G. Visual inspection of muscle surfaces did not reliably reveal all injection site lesions in the underlying musculature.

Animals↗
PubMedDate not supplied

Depletion of penicillin G residues in tissues, plasma and injection sites of market pigs injected intramuscularly with procaine penicillin G.

Procaine penicillin G was administered by intramuscular (i.m.) injection to groups of healthy 100 kg market pigs at the approved label dose (15,000 IU/kg body weight), once daily for three consecutive days; or an extra-label dose (66,000 IU/kg body weight), once daily for five consecutive days. Penicillin G residue depletion was followed in plasma, tissue and injection sites using a liquid chromatographic method. Groups of pigs were killed 1, 2, 3, 4, 5 and 8 days after the last injection with the label dose. Penicillin G was not detected in liver after 1 day of withdrawal, in muscle and fat after 2 days of withdrawal, in plasma after 4 days of withdrawal, in skin after 5 days of withdrawal, or in kidney and the injection sites after 8 days of withdrawal. Other groups of pigs were killed 1, 2, 3, 5 and 7 days after injection with the extra-label dose. In these pigs penicillin G was not found in liver after 2 days of withdrawal, in fat after 3 days of withdrawal, or in the muscle, skin, plasma and injection sites after 7 days of withdrawal. Penicillin G was found at all times in the kidneys of the groups of pigs that received the high dose. The technique used for neck injections was critical to obtain intramuscular rather than intermuscular injections. The Bureau of Veterinary Drugs, Health Protection Branch, Health Canada calculated that the appropriate withdrawal period for pigs was 8 days for a dose of 15,000 IU procaine penicillin G/kg body weight and 15 days for a dose of 66,000 IU/kg.

Adipose Tissue↗