Infectious diseases of the upper and lower bovine respiratory tract

Alhendi, Abdulsalam Bakhsh (1987) Infectious diseases of the upper and lower bovine respiratory tract. PhD thesis, University of Glasgow.

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In Chapter 1, the literature relating to bovine respiratory disease is discussed with particular emphasis on infections, infectious diseases and other disorders of the bovine upper respiratory tract. Chapter 2 describes the materials and methods used as a general basis for the studies presented in later parts of the thesis. Minor variations to these techniques or additional procedures carried out for specific investigations are presented in their appropriate chapter. Chapter 3 describes a study that was originally designed to assess the effects of the antiprostaglandin compound, flunixin meglumine, under controlled studies in calves experimentally infected with parainfluenze type 3 (PI3) virus. Throughout the course of this study, nasopharyngeal swabs were collected for mycoplasmal and bacterial investigations and tissues from various sites in the upper and lower respiratory tract were similarly examined. Flunixin meglumine significantly limited the extent of pulmonary consolidation in the test (treated) calves and thereby conferred clinically obvious therapeutic advantages. In the first group of calves subjected to detailed microbiological study, the diminished level of pulmonary consolidation correlated with lower numbers of mycoplasmal and bacterial isolations although the. range of species isolated was unaffected. In the second group of calves, the beneficial effects of flunixin meglumine were less obvious probably as the result of (unsuspected) pre-existing chronic pneumonia throughout the group. In these same calves, the total "load" of both mycoplasmas and bacteria was far greater than in the first group. Mycoplasmal isolations were far more numerous in the untreated controls although the reverse was true for bacterial isolations. As with the first group, the range of species detected was unaffected by anti-inflammatory therapy. In Chapter 4, the mycoplasmal and bacterial population within the upper and lower respiratory tract of five calves with experimentally-induced parasitic bronchitis were compared with findings in uninfected control animals. The clinical and pathological effects of infection with the cattle lungworm, D. viviparus, were also studied. A wide range of bacteria were found at all levels of the tract in the control calves. Little difference was found between lower tract infections of the two groups of calves slaughtered during the prepatent phase of the lungworm infection. However, a far wider range of bacterial species were found and far more numerous isolations were made from the calves slaughtered during the patent phase of the disease. Results relating to mycoplasmal isolations were similar but less impressive due to the smaller numbers of organisms and isolations involved. A natural outbreak of bovine pneumonic pasteurellosis was studied and described in Chapter 5. The dynamics of infection, the clinical and pathological consequences of that infection and the sensitivity profile of the organism involved (P. haemolytica Al) were investigated. While nasopharyngeal swabs were certainly found to be positive during the course of the incident, their value as diagnostic aids is questioned mainly on the basis of the ready availability of other material for diagnosis, including dead calves, on the one hand, and the fact that nasopharyngeal swabs may give rise to misleading results on the other. Finally, the mycoplasmal and bacterial flora of a number of cattle with chronic respiratory disease were studied and reported in Chapter 6. Cases of diffuse fibrosing alveolitis did not harbour many bacterial species within their respiratory tracts. In contrast, a wide range of species were found to be present at all levels of the tract in cattle suffering from chronic suppurative or chronic non-suppurative pneumonia. In each of the investigations reported in Chapters 3-6, careful note is taken of the species of mycoplasmas and bacteria isolated from the total of 54 cattle studied. In fact, apart from the calves that underwent a "natural" outbreak of pneumonic pasteurellosis, the presence of recognised pulmonary pathogens was not widespread. Mycoplasma bovis was detected on a number of occasions (particularly in the calves studied in the second experiment reported in Chapter 3) as was P. haemolytica. One organism that was isolated very frequently from all levels of the tract in a great number of the cattle studied was Acinetobacter calcoaceticus and it is suggested that further work should be carried out in order to establish whether this organism is truly pathogenic for the bovine respiratory tract. The fact that very many lower tract infections were made - even in clinically normal, non-pneumonic cattle - is discussed in relation to the findings of other workers. On the basis of this work it is suggested that lower tract infections of a mostly transient nature is normal in cattle and possibly other ruminants. It is further suggested that these infections are very probably associated with the inhalation of soil or pasture-borne bacteria along with eructated ruminal gases.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Veterinary science, Animal diseases, Animal sciences
Date of Award: 1987
Depositing User: Enlighten Team
Unique ID: glathesis:1987-76696
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 13:53
Last Modified: 19 Nov 2019 13:53

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