There are currently very few historians of veterinary medicine and outside of their scholarship there is almost nothing that has been written about veterinary history in the past thirty years. This is despite the fact that medical historians have created a large body of scholarship since the 1980s, including studies of political movements, social and cultural histories, histories of ideas of the medical profession, histories of specific diseases and histories of science. The lack of veterinary history is also striking because there has been a plethora of research corning from the field of human/animal relations. Furthermore, the history of animal care before formal veterinary education (1790s) is even more neglected and the scholarship that does exist is over forty years old and generally anachronistic-save the work of Louise Curth. This is all despite the outstanding changes that were occurring during the eighteenth century in Britain. Part of the reason that the current interpretations of eighteenth-century animal care are so anachronistic is due to the focus of historians upon the emergence of the London Veterinary College (1792) as an enlightened step toward progression. This is far from correct because a new medical specialty emerged in animal care over a century before the College. This thesis shows that those involved in the gentlemanly practice of farriery created a new specialised field of farriery that was much more medical. Like midwifery, oculism and dentistry, equine medicine became a new medical specialism. This is demonstrated by analysing elite farriery literature published between 1550 and 1800, by reconstructing the identity of eighteenth century farriery practitioners (especially those that claimed to be gentlemen), by uncovering the practice of these elite practitioners in horse hospitals and anatomy lectures. These findings suggest a new narrative of the history of animal care, showing that veterinary medicine was a product of the larger changes in equine medicine occurring well before the 1790s.

In many species a developmentally related increase in cortisol production from the fetal adrenal gland brings about the progressive maturation of fetal organ systems and triggers the onset of parturition. The fetal hypothalamus is thought to play a pivotal role in this process by secreting the neuropeptides, CRH and AVP which act upon the fetal pituitary gland to cause the secretion of ACTH. However, little is known about the ontogeny and neuroendocrine regulation of CRH and AVP secretion from the fetal hypothalamus. The experiments described in this thesis were therefore designed to investigate the maturation of CRH and AVP secretion from the fetal hypothalamus during fetal development. In order to study the secretion on CRH and AVP from the fetal hypothalamus a method for the serum-free culture of fetal sheep hypothalamic neurones was developed. The system was optimised in terms of plating density and substrate requirements and cells were maintained in vitro for up to 35 days. The functional capacity of these cells was demonstrated by measuring enhanced AVP secretion after potassium-induced depolarization, a response which was time- and calcium-dependent. To investigate the ontogeny of CRH and AVP secretion, cultured fetal sheep hypothalami removed at day 70, day 100 and day 130 of gestation (Term = day 145) were incubated with control and 56 mM potassium-containing medium. The results showed an overall reduction in basal and potassium-stimulated CRH and AVP release with advancing gestational age. These data suggested that hypothalamic secretion of CRH and AVP was reduced with advancing gestation.

β-lactoglobulin (BLG) is the major whey protein in ruminants and is found in the milk of a wide range of species. Extensive study of BLG over the years has led to the determination of the structure of the protein at 2.8AA and has revealed its ability to bind a variety of small hydrophobic molecules. However, the physiological function of BLG remains unknown despite its inclusion within the lipocalycin family on the grounds of genetic and tertiary structure comparisons as well as similarities in amino acid sequence. A protein engineering approach was adopted to study the residues involved in subunit interactions and ligand binding as well as the importance of Cys119 and 121 in determining the stability of the tertiary structure. The complete coding sequence for ovine BLG was obtained and a convenient site-directed mutagenesis system was set up. An expression system in the yeast <i>Saccharomyces cerevisiae</i> was developed in which ovine BLG was synthesised and secreted into the growth medium. Secretion was directed using the native BLG leader sequence. N-terminal sequencing of the secreted protein showed that the excision of the signal peptide occurred at the same site observed <i>in vivo</i>. Four mutant forms of the protein were generated. Cys119 and Cys121 were replaced with serine as separate mutants. Ile29, one of the residues at the subunit interface, was replaced with aspartate, and Lys70, located at the entrance to the hydrophobic pocket, was replaced with asparagine.

Orf is a highly contagious, eruptive skin disease of sheep and goats caused by a parapox virus. The virus enters through abrasions in the skin, where it replicates in the regenerating epidermal keratinocytes. Despite the generation of a specific antiviral response, orf virus reinfections can be established easily, although the lesions are milder and generally regress more rapidly than after primary exposure. The cutaneous response to orf involves the formation of a dense network of MHC class II<SUP>+</SUP> dendritic cells at the lesion. The primary aim of this project was to characterise these dendritic cells and to identify the cytokines produced by orf infected keratinocytes <I>in vitro</I>, that might be involved in the accumulation of the dendritic cells <I>in vivo</I>. <I>In vivo</I> studies of primary and secondary orf virus lesions identified the class II<SUP>+</SUP> dendritic cells to be a population of CD1<SUP>-</SUP> cells, which are also found within the dermis of normal ovine skin. A subpopulation of these cells also expressed the antigen, coagulation factor XIIIa. Factor XIIIa<SUP>+</SUP> dendritic cells comprised over half the dendritic cells seen in the network of a primary orf lesion but were only observed in small numbers, transiently, in the secondary orf lesion. All the dendritic cells lacked the expression of ovine macrophage markers. The proliferative response of the primary and secondary orf lesions also differed. High proliferative activity was observed in the epidermis and dermis in the primary response to orf but not in the secondary response. A few of the proliferating cells were identified as dendritic cells but it would appear that the dendritic cell network in both primary and secondary orf lesions does not arise by local cell division.

Bovine coronavirus (BCV) is associated with infection of the enteric and respiratory tracts of neonatal calves, and is a cause of neonatal calf diarrhoea. The virus has 4 major structural proteins: the integral membrane glycoproteins (gps) (M), the nucleo-capsid proteins (N), the spike gps (S) and the haemagglutinin-esterase gps (HE). Faecal samples from diarrhoeic calves were tested for BCV using an enzyme linked immunosorbent assay (ELISA), and attempts made to isolate the virus from positive samples in tracheal organ culture (TOC). Growth of the virus was monitored by measurement of haemagglutination (HA) titres, and confirmed by ELISA. Two out of 17 samples (12%) and 29 out of 60 samples (48%) grew to HA titres of at least 16 in TOCs obtained from bovine foetuses and young calves respectively. Seven out of 12 viruses (58%) isolated in calf TOCs were successfully adapted to growth in human rectal tumour (HRT-18) cells (MRI BCV isolates). Eight monoclonal antibodies (MAbs) were raised against S2 strain BCV (S2 MAbs) and a further 4 MAbs were supplied from the Central Veterinary Laboratory (CVL MAbs). The isotypes of the MAbs were determined, and their protein specificities investigated by Western blotting. One MAb was directed against M, 3 against N, 3 against S and 5 against HE. The MAbs were also characterised in terms of their reactions with S2 viruses in immunofluorescence (IF), neutralisation (SN) and haemagglutination inhibition (HAI) tests. Polyclonal sera and MAbs were used to probe S2 virus proteins in Western blotting experiments. The MWs of the HE, S, N and M proteins were found to be 116 (reducible to 64), 98, 52 and 21 (range 19-23) kD respectively. The S2 MAbs were used in competition ELISAs: the 4 HE MAbs defined a single antigenic region whilst the 3 N MAbs defined 3 distinct regions.

No description available.

In this study the functional integrity of relay neurones and their afferent input from optic tract fibres was monitored in the scrapie-infected dLGN throughout the incubation period. The aim of this study was to elucidate the mechanisms of scrapie-associated dysfunction at the level of the neuronal membrane. The properties of murine dLGN cells have not been characterised; a study of the membrane properties of these cells was carried out in order to ascertain if they were similar to rat and guinea-pig dLGN relay cells, and thus if results of the scrapie investigation could be interpreted in terms of the available literature on relay cell physiology in these species. The technique of intracellular recording from brain slices was used to evaluate the properties of dLGN relay cells in untreated (normal), normal brain inoculated (control) and scrapie-inoculated mice. The inoculated mice received an intraocular injection of either ME7 scrapie-infected or normal brain homogenate and recordings were made from coronal brain slice preparations of the dLGN at approximately 28 day intervals from 60 days post-inoculation. The incubation period in this model was approximately 270 days; two experimental series of inoculated mice were studied. Basic membrane properties (resting membrane potential, action potential threshold, input resistance and time constant), properties of averaged action potential shapes, the integrity of the synaptic response evoked by afferent optic tract stimulation and the membrane responses to current injection were studied in normal, control and scrapie-inoculated mice. In addition the morphology of cells in the control and scrapie-inoculated mice was monitored by iontophoresis of dye via the recording electrode. The study of normal mice demonstrated that relay neurones in the dLGN exhibited membrane response properties and responses to optic tract stimulation typical of those in the rat and guinea-pig. The basic membrane and action potential properties quantified were also similar to published studies. Significant correlations were found between: the time constant and input resistance; the after-hyperpolarisation (AHP) amplitude and spike threshold; spike amplitude and spike threshold. In terms of both their basic membrane and action potential properties murine dLGN relay cells constituted a homogeneous population. Both a fast and slow AHP followed the action potentials in murine dLGN relay cells; the slow AHP was apamin-sensitive indicating that it was mediated by the calcium-activated potassium conductance, I<SUB>AHP. </SUB>This conductance appeared to have a role in regulating the rate of action potential discharge. This study demonstrated that murine dLGN relay cells function as a homogenous population and possess similar properties to rat and guinea-pig dLGN relay cells. This is the first report of the conductance I<SUB>AHP</SUB> in dLGN relay cells.

Previous studies in this and other laboratories have, to date, failed to result in the development of a commercially useful technique for the reliable induction of twinning in cattle. The use of methods known to be efficacious in sheep have not resulted in repeatable effects in the cow. It would appear that the cow differs from the sheep in some important aspect of the control of the reproductive processes, particularly those governing follicular growth and dominance. The aim of these studies was to clarify the effects of follicular fluid proteins on follicular growth and gonadotrophin secretion. A previous study in this laboratory (Price, 1987) demonstrated that LH and FSH concentrations were grossly elevated following immunisation against a porcine follicular fluid preparation. We sought to confirm this observation and extend our understanding of the underlying processes involved. Heifers immunised against an ovine follicular fluid preparation displayed abnormally elevated peripheral FSH and LH concentrations. However, no difference in the response of heifers to an exogenous bolus of GnRH during the luteal phase of the oestrous cycle was observed. Analysis of the patterns of gonadotrophin secretion during the luteal and follicular phases of the cycle suggested that the immunised animals were unresponsive to endogenous oestradiol concentrations. Following ovariectomy, differences between immunised and control heifers were abolished, but the differences between treatment groups were restored following the insertion of a s.c. oestradiol implant, confirming our hypothesis. It would appear that the normal functioning of the oestradiol-mediated negative feedback control of gonadotrophin is dependent on the action of a follicular fluid protein. Having demonstrated the existence of such a follicular protein, it was of interest to examine the effects of the direct administration of follicular fluid proteins on gonadotrophin secretion and ovulation rate. Treatment failed to reduce peripheral FSH concentrations, although a significant dose-dependenthypersecretion of FSH was observed following the cessation of treatment. In addition, treatment with bovine or ovine follicular fluid proteins led to a significant increase in LH pulse amplitude. These effects on gonadotrophin secretion again occurred in the absence of any change in oestradiol concentrations, suggesting that the effects of treatment were most probably mediated via direct pituitary or hypothalamic effects. Collectively, we have demonstrated that follicular fluid proteins are important components in the control of the reproductive system of the cow. Such proteins are involved in the oestradiol-mediated negative feedback regulation of FSH and LH, the determination of LH pulse amplitude and the regulation of follicular growth. This latter role may represent the mechanism by which follicular dominance is effected and may present a useful target for future research attempting to develop techniques for the induction of twinning in cattle.

The main aims of the studies described in this thesis were firstly to determine the source of inhibin from the ovary of the sheep, and secondly to investigate the physiological role of inhibin in the control of gonadotrophin production, particularly that of FSH. The source of ovarian inhibin production was investigated by measuring inhibin secretion directly from the ovary <i>in vivo</i>, and by individual follicles <i>in vitro</i>. Inhibin secretion did not differ between animals at different stages of the luteal and follicular phase of the oestrous cycle. The secretion rate of inhibin was unaffected by the presence or absence of luteal tissue leading to the suggestion that, in the sheep, the corpus luteum does not produce significant quantities of inhibin. The results of these studies indicated that, like oestradiol, the majority of inhibin is produced by large (≥3mm) antral follicles. However, while most oestradiol was secreted by the large oestrogenic follicle(s), a significant amount of inhibin was also produced by large non-oestrogenic atretic follicles and by small antral follicles. A series of experiments involving passive immunisation against inhibin and/or oestradiol were then undertaken to investigate the relative importance of these two hormones in the control of gonadotrophin production. Peripheral LH concentrations were unaffected by immunisation against inhibin, and in a further experiment administration of inhibin in 'steroid stripped' ovine follicular fluid was shown to have no effect on the timing or magnitude of the oestradiol benzoate-induced LH surge in ovariectomised ewes, or on the concentration of LH following acute ovariectomy. In the passive immunisation studies, injection of antibodies to inhibin or oestradiol resulted in a highly significant, though transitory rise in the peripheral plasma concentration of FSH during both the luteal and follicular phases of the oestrus cycle, while combined immunisation against both hormones resulted in a significantly larger rise in FSH concentration of similar size to that seen following acute ovariectomy. Furthermore, treatment with physiological quantities of inhibin or oestradiol was found to partly prevent the rise in FSH concentration seen following acute ovariectomy, while a combined treatment with both hormones completely prevented this rise. Finally, immunisation against inhibin or oestradiol was shown to cause a large increase in the number of follicles per ovary, resulting in an increase in ovarian inhibin secretion following immunisation against oestradiol, and an increase in ovarian oestradiol secretion following immunisation against inhibin. These results indicate that inhibin plays an important physiological role in the control of FSH secretion during both the luteal and follicular stages of the sheep oestrous cycle, and suggest that inhibin and oestradiol act together in the control of FSH secretion.

Enzootic Abortion of Ewes (EAE) is an economically important disease of ewes, caused by the gram negative, intracellular bacterium, <i>Chlamydia psittaci</i>. The disease results in lamb loss from abortion and the perinatal death of weak lambs. Vaccines have controlled EAE for more than thirty years, however in the last decade vaccine efficacy has been poor. The primary aim of this project was to examine the cell mediated immune responses to <i>C.psittaci</i> in sheep and to identify potentially immunoprotective antigens for future vaccine studies, by their ability to stimulate both T-cell proliferation and cytokine production. Preliminary studies determined the parameters of an antigen driven, ovine lymphocyte transformation assay for <i>C.psittaci</i>, employing whole chlamydial elementary bodies (EB) as antigen. It was shown that peripheral blood mononuclear cells (PMBC) from post abortion animals would proliferate in response to chlamydial EB, although lymphocytes from naive ewes also proliferated to a lesser degree. Further studies in mice showed this latter response could be caused by a cross reaction with harmless, enteric bacteria. The development of proliferative responses of the PMBC to both EB and mitogens was also measured during gestation. Infection at this time led to the development of lasting T-cell responses and a transient suppression of the response to the T-cell mitogen, Con A. In addition, both mitogen and antigen specific responses were disrupted in the immediate pre-parturition period. These responses returned to control levels soon after lambing. The T-cell proliferative response was further characterised by probing chlamydial EB which had been separated by SDS page electrophoresis and blotted onto nitrocellulose. Individual antigens were then added to cultures of PBMC and T-cell lines generates from post abortion animals. Four antigens were identified with approximate weights of 70, 50, 38 and 30kDa which stimulated proliferation. The ability of individual chlamydial proteins to stimulate cytokine production in these cultures was also tested. The four antigens above also stimulated the production of γ-IFN in the PBMC and T-cell lines from all sheep tested. Finally, the importance of γ-IFN in a chlamydial infection was investigted in an <i>in vivo</i> mouse model, where neutralising γ-IFN with a monoclonal antibody resulted in an increase in the severity of infection in both thymic and athymic mice, when compared with control animals. Increased numbers of viable chlamydiae were isolated from tissues and increased pathological changes and serum interferon levels were demonstrated. The results presented in this thesis provide evidence for the involvement of cell mediated responses in ovine immunity to <i>C.psittaci</i>. Both T-cell proliferation and γ-IFN production can be measured, although how the responses interact with B-cells and antibody has yet to be elucidated.