The main objective of this study, as detailed in Chapter 2, was to investigate the nerves innervating the horn base in cattle and goats, paying particular attention to the contribution of the N. sinuum frontalium. The study involved the gross dissection of twenty-five cattle, aged between 2 days and 4 years, as well as twenty-four goats aged between 10 hours and 6 years. In addition to the dissections, the neurotracer Fluorogold was applied to the cut horn bases of two calves and two 15-month-old heifers. Fluorogold was taken up by cut nerves and was then transported in a retrograde manner along the nerves. The inspection of nerve sections under the fluorescence microscope revealed Fluorogold granules in the R. zygomaticotemporalis of all four animals, as well as in the N. infratrochlearis of two animals and in the N. frontalis of a single animal. Fluorogold granules were not present in either the N. sinuum frontalium or the Nn. cervicales. However, osmium-stained histological sections of the horn base revealed the presence of nerve fascicles, presumed to be branches of the N. sinuum frontalium, in the cornual diverticular lining of cattle over 2 years of age and goats over 4 years of age. These results demonstrated that in cattle the R. zygomaticotemporalis is not the only nerve supplying the horn base. Furthermore, in mature cattle and goats the N. sinuum frontalium needs to be blocked before the animal is dehorned. The objective of Chapter 3 was to investigate the sensory receptors present in the horn bud of calves and kids. For this study immunohistochemistry was used in conjunction with transmission electron microscopy. Immunohistochemistry utilized neurofilament and S-100 antibodies which demonstrated nerve fibres and Schwann cell cytoplasm respectively. In this study numerous free nerve endings, known to be nociceptors, were identified in both calves and kids. In addition, bulbous corpuscles, Merkel cells and intraepidermal nerves were demonstrated.

Lymphatic filariasis in humans is characterised by a profound bias in the immune response. Parasite specific Th1 responses, including proliferation, are dramatically impaired while Th2 responses predominate. In this study, a mouse model of filariasis was used to investigate the role of the infective form (the third stage larvae, L3) and the blood stage form (the microfilariae, mf) in modulating the immune response. Sub-cutaneous infection of BALB/c mice with L3 and mf of <I>Brugia pahangi</I> has a profound and contrasting effect on Th cell function, that appears to replicate, at least in part, the two striking aspects of the human immune response. A Th2 response predominated and polyclonal Th1 responses and antigen-specific proliferation are down-regulated in L3-infected mice. Surprisingly, antigen-specific proliferation was absent in mf-infected mice in which a Th1-biased response dominated. Furthermore, after four days of culture in the presence of antigen spleen cells from mf-infected mice, but not L3-infected mice or uninfected controls, displayed a S.I.<1. These data would suggest that spleen cells primed by infection with mf are undergoing accelerated death in culture. The remaining part of the study was focused on examining the mechanisms underlying the skewed responses in both L3- and mf-infected animals that may suggest some novel pathways operating in the infected human. Treatment of spleen cells from L3-infected mice with neutralising anti-IL-4, anti-IL-10 or rIL-2 resulted in a dramatic increase in ConA-driven proliferation, IL-2 and IFN-γ production. Interestingly, removal of the residuent spleen APC population and replacement with APC from uninfected animals also restored the defective mitogen-driven Th1 responses. Furthermore, replacing the APC population or neutralising IL-10, but not IL-4, resulted in antigen-specific IL-2 and IFN-γ indicating that <I>B. pahangi</I>-primed Th1 cells do exist in L3-infected mice but appear to be unable to respond in the presence of IL-10 perhaps operating via its effect on APC function.

Lymphatic filariasis is a long term chronic infection characterised by a Th2 dominated immune response and suppressed Ag-specific proliferation. This immunological hyporesponsiveness is most profound amongst individuals with circulating microfilariae (mf) suggesting an important role for mf in generating proliferative suppression. The use of single life cycle stage infections in murine models of filariasis has facilitated the study of stage specific mechanisms of immunomodulation. Intravenous infection of BALB/c mice with <i>B. pahangi</i> mf or L3 (the third stage larvae) leads to development of differentially polarised immune responses. At 12 d.p.i. splenocytes from L3 infected animals produce Ag-specific IL-4, IL-5 and IL-10 and show strong Ag-driven proliferative responses. In contrast splenocytes from mf-infected animals show a cytokine profile dominated by IFN-gamma and suppression of Ag-specific proliferation. After 96 hrs of Ag-stimulated culture splenocytes from mf-infected animals proliferate at levels below background indicating that an active form of suppression is operable <i>in vitro</i>. A lack of IL-2 does not account for the defective proliferative response as addition of recombinant IL-2 failed to restore Ag-specific proliferation. Splenocytes from mf-infected animals produce high levels of NO in Ag-stimulated culture which correlates inversely with their proliferative responses. No such accumulation of nitrite is seen in cultures of cells from L3 infected animals. The proliferative defect is dependent upon inducible nitric oxide synthase (iNOS) activity as inhibition of iNOS activity with either L-NMMA or AMG restored Ag-specific proliferation.

Gastrointestinal parasites infect all grazing livestock and are a major cause of economic loss. Each year in the UK, gastrointestinal parasites cost the sheep industry an estimated £85 million. Current control strategies are based on anthelmintic treatment; however parasite resistance to anthelmintic compounds is becoming an ever-increasing problem worldwide. Thus alternative control measures are now sought. This thesis comprises a number of studies which aim to investigate the genetic control of several aspects of the host response, and thus the application of such knowledge to develop alternative control strategies for gastrointestinal parasites in a commercial sheep population. Analysis of data from 6-month old Scottish Blackface lambs exposed to a mixed, natural nematode infection demonstrated that the indicator traits, faecal egg counts (FEC), immunoglobulin A activity, eosinophil count, plasma pepsinogen activity and fructosamine concentration, investigated at 6 months of age were highly heritable and strongly correlated with the worm development traits. For example at a mean age of 22 weeks the heritabilities (± SE) for fructosamine concentration, IgA activity, eosinophil count and pepsinogen activity were 0.39 ± 0.16, 0.57 ± 0.15, 0.35 ± 0.15 and 0.56 ± 0.16 respectively. Strong negative genetic correlations «-0.6) were often observed between worm development traits and eosinophil count, IgA activity and pepsinogen activity. A substantial genetic correlation was also observed between fructosamine concentration and worm length (0.67). However when such correlations were investigated across the 6-month time-period, the genetic correlations changed systematically and dramatically over time. For example, for all worm development traits, genetic correlations with eosinophil count were initially positive and moderate to strong, and then declined dramatically eventually becoming moderate to strong and negative at 5 months of age. These results provide an insight into the evolution of the genetic basis of the host parasite interaction at a time when the host immune response is developing, and help to define optimal measurement ages for selection purposes. Two quantitative trait loci (QTL) studies were carried out on populations comprising different breeds and population structure; firstly a purebred Scottish Blackface flock and secondly a wide-breed cross flock developed from aresistant breed, Gulf Coast Native, and a susceptible breed, Suffolk. Both studies identified OTL associated with parasitic resistance traits, and although there is no concordance between the results, this is possibly due to the animals being infected with different nematode species. In the Blackface study OTL associated with specific IgA activity were identified in chromosomes 3 and 20, in regions close to IFNG (chromosome 3) and the MHC (chromosome 20). OTL associated with Nematodirus FEC were identified on chromosomes 2, 3 and 14 and OTL associated with non-Nematodirus Strongyle FEC were identified on chromosomes 3 and 20. In the Suffolk x Gulf Coast Native study OTL associated with packed cell volume (PCV) were identified on chromosomes 1, 9 and 19 and with FEC on chromosomes 1, 6 and 19. OTL such as those identified in this thesis could be utilised in a marker assisted selection scheme to increase resistance to parasitic infection. In the final study interactions between different parasite species within the host animal were investigated. Significant interactions were observed between Cooperia and Te/adorsagia circumcincta, and T. circumcincta and Trichostrongylus vitrinus. Additionally Cooperia had a greater effect on FEC than T. circumcincta. The results from this study indicate that complex multi-parasitic relationships exist and hence when developing new control strategies it is essential to consider this background multi-parasitic infection and not simply focus on a specific species. In conclusion this thesis provides evidence that many aspects of the host response are under some level of genetic control. Highly heritable indicator traits have been identified along with OTL associated with resistance traits, both of which could be utilised as selection criteria to increase the response to selection for resistance to gastrointestinal parasites within a commercial sheep population. 14

No description available.

A mathematical approach was used to model seasonal variation of cyathostomin faecal egg output, and in simulating anthelmintic control strategy. The model is based on parameters of biological development of cyathostomins and climatic data. A good fit of the model prediction to the field data was obtained after some parameter adjustments. The development rate of ingested larvae to egg laying adults, survival time of adults and the assumption made in modelling the peak pasture larval availability were the main driving forces for the model prediction to fit to the observed data. The apparent fit of the model prediction to the field data obtained after parameter adjustment generally indicated some major differences between donkeys and horse in their reaction to the parasite and/or between cyathostomins of donkeys and horses. The results of the stimulation of the effect of various protocols for the timing and frequency of anthelmintic treatment on the adult cyathostomin worm burden have shown that treating donkeys only once in a year or a combination of once in a year followed by every two or even four years can substantially reduces and maintains the parasite burden far below the pre-treatment level for many years. Generally the study made has revealed that the non-strongyle gastrointestinal parasites of donkeys are highly prevalent and have a high pathogenic potential, and the findings of cestodes and trematodes are not accidental or unusual, as previously suggested.

Recognition, alleviation and control of pain are central to ensuring good welfare in food producing animals. An intervention trial was conducted on 117 dairy cows with naturally-occurring, mild or moderate, clinical mastitis in a single quarter in order to investigate the effect of the administration of the non-steroidal anti-inflammatory drug, meloxicam (Metacam, Boehringer Ingelheim Animal Health GmbH) used in conjunction with an intramammary antibiotic infusion of cefquinome (Cephaguard LC Intramammary, Intervet UK Limited, Milton Keynes). Clinical and laboratory parameters were investigated to assess their usefulness as objective markers of pain. Measuring the cows’ response to a mechanical stimulus assessed altered pain processing. Heart rates, respiratory rates and rectal temperatures of cows were higher in moderate cases compared to milk cases of clinical mastitis (p<0.001). The hindleg stance of cows, as measured by hock-to-hock distance, with clinical mastitis was greater than in normal cows (p<0.001). Alterations in the response to mechanical stimulation were recorded in cows with both mild and moderate clinical mastitis and treatment with meloxicam was shown to attenuate the mechanical alterations (p=0.04). There was however, no difference in cows that received one, compared to three doses of meloxicam (p>0.05). On bacteriological examination to the recruited cases, 30% of isolates yielded S uberis, 24% yielded no growth, 22% E coli, 11% Staph aureus, six per cent other microbiological species, four per cent A pyogenes and three per cent S dysgalactiae. When compared with mild cases of mastitis the moderate cases had a greater proportion of isolations of S uberis (p<0.01) and a smaller proportion of no growths (p<0.01). There was no effect of mastitis on the fat percentage of milk, as judged by the comparison of affected quarters to diagonally opposite quarters and to normal cows. The protein content of milk increased with mastitis and the lactose content decreased. The most common somatic cell type in quarters affected with mild and moderate mastitis on the day of recruitment to the study were polymorphonuclear cells, whereas large mononuclear cells were the predominant cell type in normal animals. The concentration of haptoglobin in milk from the affected quarters of cows with moderate mastitis was greater (p<0.01) than that in milk from affected quarter of cows with mild mastitis. Mammary-associated serum amyloid A concentrations were higher in the affected quarter of cases of milk and moderate clinical mastitis than in normal cows (p<0.001). Concentrations of the inflammatory mediator, prostaglandin E2 in milk were lower in mild cases of clinical mastitis compared to moderate cases (p<0.05). In conclusion, physiological and laboratory parameters may serve as indicators of clinical mastitis, help differentiate between different severities of clinical mastitis and, therefore, aid in appropriate targeting of therapy.

The effects of thermal environments from 20oC. to 40oC. at high and low humidities on the physiological reactions of young calves.

This research applied the psychometric approaches of proxy human chronic pain and HRQL instrument development to the development of an instrument to measure chronic pain in the dog, using the owner to provide a proxy report. The development of the instrument followed established steps designed to ensure an instrument’s validity: the identification of all domains relevant to the measurement of interest; generation of a pool of potential instrument items; selection of instrument items from the item pool, and validation of that selection; design and pre-testing of the prototype instrument; field-testing of the instrument to establish its psychometric properties. Domain identification was carried out through interviews with 47 owners of dogs suffering chronic pain. Potential items (descriptive terms) were generated using questionnaires completed by 165 dog owners. These domains and the items selected were subsequently validated by 12 veterinary practitioners and by 10 owners of dogs suffering chronic pain. The validated list of items was incorporated into a structured questionnaire, and this instrument was pre-tested using 26 dog owners. The finished instrument was then field-tested using the owners of 155 dogs who completed a total of 390 questionnaires prior to and during treatment at the University of Glasgow Small Animal Hospital and at a local Veterinary Practice, a majority of which dogs were suffering from chronic degenerative joint disease (DJD). Factor analysis of the instrument responses for dogs suffering DJD revealed an interpretable 12-factor model, in which factors were interpreted as domains of canine HRQL: ‘vitality’, ‘physical limitation’, ‘lethargy’, ‘anxiety’, ‘aggression’, ‘emotional upset’, ‘appetite’, ‘consistency of behaviour’, ‘mental disturbance’, ‘attention-seeking’, ‘sadness’ and ‘acceptance’. This analysis provided evidence for the construct (factorial) validity of the instrument, since responses to instrument items revealed an underlying structure that reflected the construct upon which the instrument was developed. Scores were calculated for each of the 12 domains of HRQL identified by the factor analysis, and these were able to discriminate between dogs with chronic pain and healthy dogs on >86% of occasions. Profiles of HRQL scores obtained for dogs with chronic pain were compared with those obtained for healthy dogs in a control group, and differences in these profiles were observed. An examination of changes in HRQL domain scores over time for individual dogs revealed that these scores tended to reflect clinical change in those individuals. The process described here offers a novel approach to the development of chronic pain and HRQL instruments for a range of animal species, and may have relevance for human chronic pain and HRQL instrument development.

The area of the skull incorporating the tympanic bulla (TB) and temporomandibular joint (TMJ) is significant clinically in the dog, cat, and more recently the rabbit. Diagnostic imaging is important in the assessment of disease of these structures but there is a relative lack of comparative anatomical information relating to the normal that may be used to understand the abnormal features encountered when using currently available diagnostic imaging modalities. A review of conventional radiography demonstrated that views for imaging the canine and feline TB could be extrapolated for use in the rabbit but the same did not apply to the TMJ. Plastinated multiplanar anatomical sections proved useful for the identification of anatomical features on corresponding tomographic images. Ultrasound imaging of this region has not been widely reported but allowed evaluation of the TB in all three species, although the information obtained regarding the TMJ was limited. Directly acquired computed tomography (CT) and Magnetic Resonance (MR) images were of better quality than previous publications due to technological advances in the equipment available. Directly acquired images were still better than reconstructed ones and reduced image acquisition times are likely to make this viable in clincal cases. CT produced optimal imaging of the TB but only allowed assessment of the bony elements of the TMJ. Little information was obtained regarding the normal TB using MR imaging due to the indistinguishable signal voids produced by the bone wall and gas lumen. However, T1 weighted sequences allowed identification of intra-articular TMJ soft tissue structures in the dog and rabbit. While opening the mouth altered the areas of the TMJ examined using each modality, it did not improve visualisation of the intra-articular structures. The introduction of fluid into the middle ear cavity of dog, cat and rabbit cadavers aided identification of the TB and acted as a model of one of the major features of acute otitis media, or inflammation of the middle ear cavity. CT was most accurate at identifying middle ear material in cadavers and clinical cases, while ultrasound produced better results than radiography in cadavers but not clinical cases. These imaging modalities also proved useful in the characterisation of the unexpected anatomical anomalies that were encountered during the study. The results of this study indicate that the optimal imaging technique will vary with the species and area being examined, and that extrapolation between species is not always appropriate. Continual improvements in technology and image quality make studies such as this necessary to allow selection of the most appropriate single or combination of imaging techniques and to obtain the maximum amount of information from the resulting images.