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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Studies on ovarian and uterine function in the mare

Watson, E. D. January 2002 (has links)
The submitted collection of papers represents my work in the area of equine ovarian function and dysfunction. During spring transition, the endocrinological events responsible for recruitment of large anovulatory follicles appear to resemble recruitment of preovulatory follicles in the natural breeding season. These large follicles contain only low concentrations of progesterone and oestradiol. They have low expression of mRNA encoding steriodogenic enzymes, have poor development of the theca interna and are poorly vascluarised. These follicles are therefore showing signs of atresia while they are actively increasing in size. In preovulatory follicles, concentrations of inflammatory mediators increase as ovulation approaches, and fluid from preovulatory follicles is chemotactic for leucocytes. Intrafollicular treatment with indomethacin delayed ovulation which supports the central role for inflammation in the ovulatory process. It is also likely the matrix metalloproteinases are involved in the profound tissue remodelling that occurs around ovulation. Control of follicular growth has been studied and equine follicles are dependent on gonadotrophin stimulation when they reach 10 mm in diameter and on LH stimulation for final growth and maturation. The equine CL is dependent, at least in part, on trophic support by LH and luteal cells bind LH <i>in vitro</i>. Steroidogenesis in the CL varies before and after development of the endometrial cups in pregnancy. StAR protein increases after endometrial cup formation, allowing greater mobilisation of substrate for steroid synthesis. Although P450<sub>arom</sub> is consistently present in the equine CL, P450<sub>C17</sub> increases after the endometrial cups form, allowing oestrogen synthesis by the CL in the pregnant mare. The cell types in the equine CL appear to co-operate in steriodogenesis, with P450<sub>C17</sub> located in small luteal cells, and P450<sub>arom</sub> in large luteal cells. Maintenance of the CL in early pregnancy appears to be caused by the inhibition of endometrial PG synthesis by the conceptus, although the conceptus itself produces PGs. The demise of the CL involves apoptosis and is preceded by a decrease in angiogenesis.
2

The fuctional anatomy of the trigeminal nerve of the horse

Newton, Stacey Anne January 2001 (has links)
It was hypothesised that the aetiopathology of the condition of headshaking involves abnormalities of either the structure, function or behaviour of the trigeminal nerve. Specifically it is believed that the second division of the trigeminal nerve, represented by the caudal nasal nerve (CNN) is involved. In addition it is hypothesised that such cases are equine analogues of the condition of trigeminal neuralgia (TgN) in humans. To answer these hypotheses the following work was undertaken: 1. Studies of a series of clinical cases of headshakers to assess similarities/dissimilaritie swith TgN. 2. Studies of the pharmacokinetics of carbarnazepine (CBZ) in headshakers. 3. Isolation and purification of equine P2 myelin protein and its use in investigating the serum levels of P2 myelin protein antibody in the normal population, cauda equina neuritis (CEN) and headshakers. Serum antibodies to P2 myelin protein have been identified in demyelinating diseases in humans - Guillain-Barré Syndrome (GBS), CEN and headshakers. 4. Studies of the macroscopic and microscopic anatomy of the trigeminal nerve in normal controls and headshakers. 5. Studies of the immunocytochernistry of the trigeminal ganglia, brainstem and root areas of normal controls and headshakers. 6. Magnetic Resonance Imaging (MRI) studies of the equine head. 7. Studies investigating total counts and sizes of nerve fibres of the trigeminal nerve. 8. Equivalent comparative studies of the physiology of the trigeminal nerve. The results of the clinical study support the hypothesis that headshaking is similar to TgN since both syndromes show evidence of seasonality and unilateral presentation of clinical signs, the presence of a trigger zone and a positive response to CBZ therapy in several cases. In headshakers, the trigger zone appears to be in the nasal cavity and the positive response to CNN anaesthesia supports the hypothesis that this branch of the trigeminal nerve is affected. CBZ therapy is effective in some cases of headshaking but pharmacokinetic studies demonstrate that the non-response in some cases is likely due to under dosing and problems of interference with absorption. Isolation of P2 myelin protein was successful but P2 myelin protein antibodies were not identified in CEN and headshaking cases. This suggests that there is no evidence that the aetiopathogenesis of headshaking involves an immune-mediated mechanism elicited by antibodies to P2 myelin protein. No gross or microscopic abnormalities were identified in the headshakers. Some differences were observed between normal controls and headshakers in total nerve counts and the identification of neuropeptides in the trigeminal system. However the significance of these findings is unknown due to the small numbers of cases involved. No vascular compression was identified at the trigeminal root entry zone (REZ) as reported in TgN cases. MRI techniques are of no use in post mortem specimens of the equine head for examination of the neurovascular relationships of the trigeminal nerve. More research on the use of intravascular contrast in post mortem head specimens is required, though in preference, the use of anglography with MRI in the anaesthetised animal, would likely be much more successful. Initial studies of the neurophysiology of the trigeminal nerve have demonstrated that the technique of evoked CNAPs applied to human TgN cases can be applied successfully to the horse. The equine trigeminal nerve has a very fast conduction velocity, faster than that reported in previous studies of other species. This work fails to conclusively support the hypothesis that headshaking is similar to TgN since no pathology or vascular compression at the REZ was identified. However, the clinical presentation and response to CBZ are similar in both syndromes. Further investigation of trigeminal nerve CNAPs in the horse appears to be the most promising method to investigate any alteration in function in headshaker cases as reported in TgN cases.
3

Development of indicators for the on-farm assessment of sheep welfare

Phythian, Clare Joan January 2011 (has links)
The objective of the work presented in this thesis was to develop valid, reliable and feasible indicators for the on-farm assessment of sheep welfare. In the absence of a reference test for animal welfare assessment, the welfare indicators in this thesis were developed within the Farm Animal Welfare Council( FAWC) Five Freedoms framework. A scientific literature review and the consensus opinion of a panel of experts were used to judge the face and consensual validity of a selection of indicators of sheep welfare. Experts identified 193 current on-farm welfare issues for sheep and subsequently suggested a range of animal- (n = 26), resource-( n = 13) and management-based indicators( n = 22) in order to assess the on-farm welfare of adult sheep( > 1 year-old), growing lambs (> 6 weeks -<I year-old) and young lambs (< 6 weeks-old). The diagnostic validity of 49 non-invasive, animal-based indicators was tested during a cross-sectional study in which 8 observers independently assessed the indicators on 4686 sheep and lambs from 50 farms in England and Wales. This study found that many indicators, including measures of lameness, body condition, and cleanliness, were reliable, sensitive and specific between observers of differing occupations and levels of training and experience. The measures were also feasible to apply and capable of detecting between-farm variation in conditions associated with sheep welfare. Studies in the use of qualitative behaviour assessment (QBA) also found good levels of reliability for observer assessments of video-clips of sheep behaviour. The ability of animal-based indicators to detect seasonal variation in sheep welfare conditions was investigated on 5740 adult sheep and growing lambs from 12 sheep farms during a one-year longitudinal study. Animal-based indicators including measures of lameness, body condition and QBA, were found to be capable of detecting seasonal variation, suggesting that the tests were valid under different management conditions and across the different events of the annual sheep production cycle. Overall, a low proportion of the sample population was observed with conditions that affected sheep welfare, which may have been the result of non-random sampling of farms. However, for the purposes of this thesis the ability of the indicators to detect important welfare conditions at a low prevalence provide further evidence of their validity. Resource-based assessments were feasible to perform but assessments were limited to certain periods of the production cycle. As management-based indicators relied on the accuracy of farmer interviews and access to farm records, the use of animal-based measures may be a more appropriate means of assessing some aspects of flock welfare. A final set of valid, reliable and feasible indicators of sheep welfare, comprising 28 animal- and II resource- and management-based measures, was recommended on the basis of field validation results and expert opinion. Key animal-based indicators that were found to be reliable, responsive and robust under extensive and intensive farming systems and suitable for assessing both sheep and lambs were lameness, demeanour and body condition. It is suggested that these indicators should be applied in future on-farm protocols by trained assessors who are calibrated to the StandardO Operating Procedures (SOP's). The interpretation of animal-based indicator assessments was guided by expert opinion in the form of preliminary cut-off points, which defined the level of acceptable and unacceptable flock welfare. As a result, the work presented in this thesis can inform the method of assessment and interpretation of a selection of valid, reliable and feasible on-farm indicators of sheep and lamb welfare.
4

The role of fimbriae and flagella of Escherichia coli O78:K80 in the pathogenesis of avian colibacillosis

La Ragione, Roberto Marcello January 2000 (has links)
Avian colibacillosis is an economically important bacterial disease of domestic poultry which despite efforts to control the disease, has increased with intensification of farming practises and the emergence of antibiotic resistance. E. cola isolates implicated in avian colibacillosis commonly elaborate surface organelles known as fimbriae and flagella and it has been hypothesisedt hat these surface appendagesm ay be important in pathogenesis. To investigate the role of fimbriae and flagella of E. coil 078: K80 in the pathogenesis of avian colibacillosis, defined isogenic single and multiple afimbriate and aflagellate mutants were constructed in a well characterised avian E. coli 078: K80 isolate (EC34195) and tested in various in vitro and in vivo models. In in vitro adhesion studies type 1 fimbriae were found to contribute significantly to adhesion of E. coli 078: K80 to cultured epithelial cells and tracheal and gut tissue explants. Curli fimbriae contributed significantly to adhesion to gut tissue explants whereas flagella contributed significantly to adhesion in the presence of mucus. In in vivo colonisation and invasion studies where day-old SPF chicks were dosed with the wild-type or isogenic afimbriate and aflagellate mutants type 1 fimbriae, curli fimbriae and flagella all contributed to colonisation and invasion. In in vivo persistence studies type 1 fimbriae, curli fimbriae and flagella all contributed to the persistence of E. coli 078: K80 in the chick. In a competition persistence model where day-old SPF chicks were dosed with wild-type and isogenic afimbriate or aflagellate mutantsf lagella>curli>type I were significant for the persistenceo f E. coli 078: K80 in the chick. 2
5

Studies on the diffusion of mepivacaine between adjacent synovial structures in the horse

Gough, M. R. January 2000 (has links)
Introduction. This thesis reports the incidence of diffusion of mepivacaine between the forelimb distal interphalangeal joint and navicular bursa, the intercarpal and radiocarpal joints, the tarsometatarsal, centrodistal and tarsocrural joints of the hock and the three stifle compartments in the horse. Materials and methods. The serum urea and synovial fluid urea concentrations were compared in 42 horses. Known dilutions of synovial fluid were made and the acute urea concentrations compared with the expected urea concentrations. For the diffusion studies thirty-three fresh cadavers were used. Synovial structures in the forelimb foot, carpus, hock and stifle in the left limbs and an alternate adjacent synovial structure in the right limbs were injected with mepivacaine. Results. The serum urea and synovial fluid urea concentrations in 42 horses proved to be equivalent (p<0.005). Results of dilution studies in synovial fluid indicated that changes in urea concentration accurately reflect dilution. Mepivacaine was detected in 25/25 (100%) adjacent navicular bursa, distal interphalangeal, tarsometatarsal and centrodistal joints and in 20/20 (100%) lateral femorotibial and medial femorotibial joints. Diffusion between other adjacent synovial structures were: intercarpal to radiocarpal joint 24/25 (96%), radiocarpal to intercarpal joint 21/25 (84%), centrodistal to tarsocrural joint 22/25 (88%), tarsometatarsal to tarsocrural joint 23/25 (92%), lateral femorotibial to femoropatellar joint 18/20 (90%) and medial femorotibial to femoropatellar joint 17/20 (85%). Mepivacaine was detected at concentrations >0.3 mg/l ranging from a minimum of 9/25 (36%) in the intercarpal joint from radiocarpal joint injection to a maximum of 25/25 (100%) in the navicular bursa from distal interphalangeal joint injection. At mepivacaine concentrations >100 mg/l detection ranged from 2/25 (8%) in the intercarpal joint from radiocarpal joint injection to 19/25 (76%) in the centrodistal joint from tarsometatarsal joint injection. Conclusions. The results show that serum and synovial urea concentrations are the same. The results show greater diffusion of mepivacaine between adjacent synovial structures than assumed from previous anatomical, latex injection and contrast arthrography studies. Therefore, commonly performed intra-synovial local analgesic techniques in the horse are not as specific as first thought.
6

Some blood pressure studies in normal horses and in horses affected with chronic obstructive pulmonary disease

Dixon, P. M. January 1979 (has links)
No description available.
7

A study of the distribution of the bronchial tree, the pulmonary artery and the pulmonary vein in the lungs of the sheep

Hare, W. C. D. January 1954 (has links)
No description available.
8

The California Mastitis test : what's the value?

Roberts, Judith M. January 2012 (has links)
No description available.
9

Calcium and phosphate metabolism in cattle and sheep

Moodie, E. W. January 1964 (has links)
No description available.
10

Molecular definition of paratuberculosis pathologies by functional genomics

Smeed, J. January 2008 (has links)
Paratuberculosis (Johne’s disease) is a chronic intestinal disease of ruminants caused by <i>Mycobacterium avium </i>subspecies <i>paratuberculosis</i> (MAP). Three forms have been described in sheep – multibacillary, paucibacillary and asymptomatic. Real-time RT-PCR (qPCR) and microarray analyses were used to compare gene expression in ileal tissue from sheep with the three forms of the disease to try to understand the immune responses underpinning these three defined pathologies. All animals from the infected flocks were IS900 positive by qPCR and therefore infected with MAP. Asymptomatic sheep had no clinical signs of disease, showed no evidence of acid-fast bacteria (ZN-), exhibited normal histology of the terminal ileum and were seronegative. Paucibacillary sheep were ZN- and showed lymphocyte/eosinophil infiltrate into the lamina propria. 2/6 of the paucibacillary animals were seropositive. Multibacillary sheep had high numbers of ZN+ bacteria associated with infiltrating sheets of epithelioid macrophages and were seropositive. Control sheep were IS900 negative and thus uninfected with MAP. qPCR experiments confirmed that pauci- and multibacillary forms are linked to the differential expression of IFNγ and IL-10 respectively. Increased levels of the proinflammatory cytokines IL-1β, IL-8, IL-18, TNFα and TRAF-1, indicative of persistent inflammatory lesions, were observed in clinical tissues. IL-3 was detected at low levels in all infected animals but never in uninfected control samples. IGFBP-6 was upregulated and CXCR4 downregulated in paucibacillary samples compared to multibacillary samples. Microarray experiments discovered 64 differentially expressed genes. Ten genes were found to be differentially expressed in infected tissue compared to uninfected controls, and a further eight in clinical tissues compared to uninfected controls. Fifteen genes were differentially expressed in clinical tissue compared to asymptomatic tissue. Six genes were quantified by qPCR and validated in microarray data well. Pathway analysis of the microarray data identified several immune pathways that are involved in pathogenesis. Infected tissues displayed upregulation of the genes involved in TCR signalling and complement activation, and downregulation of MHC class II genes. In addition, clinical tissues displayed upregulation of genes involved in the JAK-STAT and TLR2 signalling pathways, NK cell cytotoxicity and antibody production. Multibacillary tissues also displayed upregulation of genes involved in leukocyte migration. Overall, these data confirm that multibacillary pathology is linked to type 2 and paucibacillary pathology is linked to type 1 immune responses and identify novel genes and gene pathways for future analyses.

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