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Subject: search.filters.subject.300904 Veterinary diagnosis and diagnostics

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    Veterinarians' perspectives of neurology : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand
    (Massey University, 2024-10-29) Shea, Anita
    Negative perspectives of neurology are commonly reported in medical education and have led to concerns regarding patient care and insufficient numbers of neurologists. Most of the proposed contributors to this “neurophobia” relate to intellectual difficulty learning and applying neurology knowledge. However, most studies to date have explored neurophobia superficially and differences between how neurophobia is defined and how it is measured challenge what the term means and our understanding of why it develops. Despite this lack of clarity, there are increasing numbers of reports that cite educational interventions to combat neurophobia. While the medical and veterinary professions share many similarities, there is very little research exploring neurophobia in veterinary medicine. It is unclear whether negative perspectives of neurology are common in veterinarians, and what contributes to the development of veterinarians’ perspectives of neurology. The overarching aims of this research were to better understand veterinarians’ perspectives of neurology, how and why they develop, and the effect they can have on further learning and clinical experiences. This research investigated veterinarians’ and veterinary students’ perspectives of neurology using a mixed method approach. Thematic analysis of semi-structured interviews explored how veterinarians’ experiences, and their reactions to those experiences, contributed to their overall attitude towards neurology. Statistical analysis of subsequent surveys of veterinarians and undergraduate veterinary students focused on those with negative or positive attitudes towards neurology to further explore these differing perspectives. The findings of all studies were integrated to obtain a holistic understanding of how similar inciting experiences can lead to different attitudes towards neurology. Intellectual difficulty learning and applying neurology was reported by most participants, regardless of their attitude towards neurology. Differences between participants with negative or positive attitudes towards neurology were often dictated by the individual’s affective responses to that difficulty, which in turn were shaped by personality traits, values, professional identity, and the ability of the individual to resolve internal conflict. Resolution of internal conflict could improve one’s attitude towards neurology. In contrast to medical literature on neurophobia, these findings suggest that an individual’s attitude towards neurology is determined by the way they react to intellectual difficulty, not the difficulty itself. This distinction has implications for educational interventions for any difficult subject, not just neurology.
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    Investigation of palpable udder defects in non-dairy ewes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science, Massey University, Palmerston North, New Zealand
    (Massey University, 2023) Zeleke, Mandefrot Meaza
    Udder defects have been associated with low survival rates and reduced live weight gains in pre-weaned lambs and increased pre-mature culling of ewes. However, there are gaps in our understanding of the pathology of udder defects and changes that may occur over time. To address these issues three studies were undertaken. Chapter 4 describes the effect of palpable udder defects (hard or lump) on milk production and composition, while Chapter 5 assesses changes in udder half defects over time. In chapter 6, aerobic bacterial species were identified, and in Chapter 7 the gross and histological lesions associated with palpable udder defects were described. Milk yield was reduced by more than 50% in defective udder halves; however, the whole udder milk yield depended on the persistence and type of the defect and contralateral udder half compensatory increase. Udder half defects changed over time in lactation and during the non-lactating period. Udder halves categorised as hard or lump at pre-mating were more likely (Relative risk ratio (RRR= 6.8-1440) to be defective at some time in the future, within the same year or in the following season, compared to the udder halves categorised as normal. Mannheimia haemolytica and Streptococcus uberis were identified as dominant bacteria from defective udder halves while S. aureus was isolated from both defective and normal udder halves in similar proportions. Among several bacterial species identified during lactation, Mannheimia haemolytica, Staphylococcus xylosus, and Streptococcus pluranimalium were more stable over time. Udder halves categorised as hard was described as moderately enlarged and contained a single large abscess on dissection while typical histology showed the presence of pyogranuloma with extensive chronic inflammation and granulation tissue. The pathological changes in udder halves categorised as lump varied from normal appearance to severe chronic inflammation with a purulent exudate. In conclusion, due to an increased risk of future recurrence and long-term damage to the mammary tissue associated with udder halves categorised as hard, ewes with such defects should be culled. In contrast, udder halves categorised as lump showed marked pathological variation; therefore, additional studies are needed to determine more accurately, by sub-categorising and/or use of methods other than udder palpation (e.g., ultrasonography). Keywords: Bacteria, Change Over Time, Gross pathology and Histology, Milk Composition, Milk Yield, Palpable Udder Defect, Somatic Cell Counts.
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    Detection and management of lameness in dairy cattle in New Zealand and Tanzania : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University Te Kunenga Ki Pūrehuroa, University of New Zealand, School of Veterinary Science, Manawatu
    (Massey University, 2022) Werema, Chacha Wambura
    Alongside mastitis and infertility, lameness is one of the key animal health challenges on dairy farms. Lameness is particularly challenging due to the complex nature of its aetiopathogenesis and its multiple risk factors. Early detection combined with effective treatment, management and prevention are integral approaches to reducing the impact of lameness on dairy farms, improving productivity, and enhancing animal health and welfare. This thesis focused on improving detection and improved management. Visual locomotion scoring (LS) is currently the most widely used system for detecting lameness worldwide but has attributes that limit its usefulness and application. The first part of this thesis presents three studies looking at alternatives to LS: infrared thermography (IRT) and in-parlour scoring (IPS). IRT was compared to LS in both New Zealand and Tanzania, while IPS was tested in New Zealand alone. Both IRT and IPS proved to be useful alternatives to LS, but further research on more farms across more countries is required before they can replace LS for lameness detection on dairy farms. The second part of the thesis evaluates the response to a three timepoint regime of prophylactic hoof trimming (dry-off, early lactation, and end of lactation) on; 1) lameness incidence and time from calving to increased locomotion score, and 2) the distance from the external claw sole surface to the distal phalanx (DDP), and how this relates to lameness risk. On the study farm, prophylactic hoof trimming did not decrease lameness incidence or time to clinical lameness (locomotion scores ≥2). However, it did increase the interval from calving to an observable change in gait (locomotion scores ≥1). In regard to DDP, the study showed that DDP was not affected by trimming and that changes in DDP did not affect the hazard of increased locomotion score, i.e. either locomotion scores ≥1 or locomotion scores ≥2. Keywords: lameness; locomotion scoring; infrared thermography; in-parlour scoring; prophylactic hoof trimming; dairy cattle; pasture-based system; tropical
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    The diagnosis of an outbreak of Mycoplasma bovis clinical mastitis in a multi-farm North Otago farming operation : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University, Manawatū, New Zealand
    (Massey University, 2021) Kearney, Kevin Patrick
    Mycoplasma bovis (M. bovis) causes a multitude of disease syndromes in dairy cattle including clinical mastitis (CM), arthritis and pneumonia. The detection in July 2017 of M. bovis, for the first time in New Zealand (NZ), on a South Island dairy farm, prompted a national animal disease response. This descriptive study aims to describe the clinical and diagnostic test findings of an outbreak of M. bovis CM, on a large multi-farm dairy enterprise where there was a single hypothesised infection source and date. Samples were collected as part of surveillance activities on-farm and at slaughter, together with farmer-selected CM cows, to provide results from real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) tests of bulk tank milk (BTM), individual cow serum ELISA tests, quarter milk samples (QMS), and palatine tonsils qPCR tests. Post-mortem sampling of the mammary glands of M. bovis CM cases was also performed. Positive BTM PCR, supported by BTM ELISA, confirmed infection in two of the four dairy herds in the enterprise and herd-level serology (serum ELISA) confirmed infection in a third herd. There was a common clinical presentation in infected herds of an unusually high incidence of apparent treatment failure (ATF) of non-systemically ill, multiple quarter CM cases, from some of which M. bovis was detected. Individual CM cases were found in the main to be QMS M. bovis qPCR positive, serum ELISA positive and palatine tonsil qPCR positive. In approximately 70% of M. bovis CM cases, M. bovis was found to be the sole pathogen. A smoothed function model between serum ELISA and time from first diagnosis of CM, from which M. bovis was detected, predicted that the average interval between clinical diagnosis and a serum ELISA test positive result was five days. The higher observed agreement between the serum ELISA and palatine tonsil qPCR, was for M. bovis CM cows sampled on-farm compared with cows sampled at slaughter. Gross lesions of fibrosis, caseous necrosis and cystic dilation in the udders of M. bovis positive CM cows were seen together with granulomatous and suppurative inflammatory patterns histologically. High immunoreactivity in immunohistochemistry for the M. bovis antigen was also present. From the key diagnostic test findings, M. bovis was likely to have been one of several pathogens which caused individual cases of CM on the farming enterprise, and in many cases may have been the sole cause of CM cases. The results of this study can raise awareness of and provide information to aid dairy farmers and veterinarians determine if M. bovis has a role in CM outbreaks with unexpectedly increased numbers of treatment failures and can inform the regulatory response for surveillance and testing of herds and individual cattle for M. bovis.
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    Prognostic significance of tumour-associated inflammation related markers in canine mammary gland tumours : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterniary Science at Massey University, Manawatū, New Zealand
    (Massey University, 2020) Ariyarathna, Harsha
    Canine mammary gland tumours (CMGTs) are a major cause of illness and premature death in female dogs, especially in countries like Sri Lanka where early de-sexing is not a routine veterinary practice. Therefore, there is a need for prognostic markers which can better predict the behaviour of a CMGT. In human breast cancers (HBCs), some markers of tumour-associated inflammation (TAI) have been shown to better predict prognosis than many conventional prognostic markers. This thesis investigated whether TAI prognostic markers adopted from human breast cancers are similarly prognostic for CMGTs. The prognostic markers investigated in this thesis included tumour stromal mast cell density determined by toluidine blue staining, gene expression of chemokines: CCL5, CXCL12, CXCL10, and chemokine receptors: CXCR3, CXCR4, CXCR7, CCR4, CCR9 and gene expression and immunostaining of two immune checkpoint molecules: programme death ligand-1 (PD-L1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) . Similar to HBCs, all markers except CXCL10 and CCR4 were prognostic of the disease outcome determined by disease-specific survival times of the dogs with mammary neoplasms. Of them, stromal mast cell density, CCL5 gene expression and PD-L1 immunostaining were prognostic independent of tumour size, tumour histological grade, and lympho-vascular invasion observed in histological sections. In conclusion, this thesis identified that similar to HBCs, TAI related prognostic markers are useful to better predict the behaviour of CMGTs while stromal mast cell density has the potential to be adopted for routine laboratory prognostic determination. In addition to identification of prognostic markers, surveys of CMGTs in Sri Lanka and New Zealand conducted for sample collection gathered large amounts of information that allowed a comparison of CMGTs between the two countries. These studies allowed a determination of the characteristics of dogs with CMGTs, as well as allowing histological characterisation of the tumours within the two countries.
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    Mortality and failure of passive transfer of immunity in New Zealand dairy calves : a thesis presented in partial fulfilment of the requirements for the degree of PhD in Veterinary Science at Massey University, Manawatu, New Zealand
    (Massey University, 2019) Cuttance, Emma Louise
    In recent years, there has been a growing interest from consumers globally about the welfare of the animals producing their food. In New Zealand, particular attention has been paid to the treatment of calves though the help of welfare lobbyists bringing certain New Zealand farming practices into the spotlight. Unlike most of the rest of the world, in New Zealand, cattle are born outdoors and are housed only for a short period of time. This has meant that international research on mortality, colostrum management and calf health has been generally not applicable, and that we need New Zealand-based data to be able to benchmark key outcomes. We had two major objectives for this research. The first was to accurately estimate perinatal and postnatal mortality on New Zealand dairy farms and to identify potential risk factors. The second objective was to focus on one factor that is known to be strongly associated with calf mortality: the failure of the calf to take up sufficient colostral antibodies to provide protective immunity until the calf’s antibody-production system becomes fully effective (“failure of passive transfer”; FPT). The study aimed to estimate the prevalence of FPT across New Zealand dairy farms, identify potential risk factors that may be associated with that prevalence and to evaluate the effects of FPT to the end of first lactation. We found that, despite the significant differences between the New Zealand system and those of the northern hemisphere, the mortality risk of perinatal (5.7%) and postnatal calves up to weaning (4.1%), then weaning to ~27 months (2.7%) was comparable. However, our review of the previously published data highlighted that the quality of data collection, transparency in methods and validation of records in most other studies, particularly retrospective ones, was poor, limiting the validity of such comparisons. We identified substantial variation between farms in mortality risk (2.2-8.6% perinatal, 0-11% postnatal pre-weaning, 0-7.9% weaning to ~27 months), thus significant reductions in calf mortality may be achievable on many farms. One factor responsible for this variation may be farm-level prevalence of FPT which averaged at 33% and ranged from 5-84%. In intensive systems, separating calves from their dam and feeding high quality colostrum within 4-6 hours of birth reduces FPT. In contrast, our research found no effect of earlier colostrum feeding on FPT prevalence and the only significant herd level risk factors were region and herd size. This may be at least partly due to the difficulty of increasing calf pick-up to the frequency recommended for intensive farms. FPT increased mortality and morbidity and to a lesser extent decreased weight gain in the first 12 months, however showed no appreciable effect after this time.
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    Development of methods to evaluate hoof conformation and lameness in New Zealand dairy goats and the effects of trimming regimes on goat hoof health : a thesis presented in complete fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University (Manawatu) New Zealand
    (Massey University, 2020) Deeming, Laura
    Lameness is a debilitating and painful condition. It is considered a major welfare and economic issue in the dairy industry, due to its high prevalence and associated production losses, and the serious impact it has on individual animals. One major risk factor for lameness is hoof overgrowth and consequently poor hoof conformation. Dairy goats in New Zealand are largely housed indoors; such environments offer limited opportunity for natural hoof wear, therefore hoof overgrowth is likely to be common. However, there are few data in New Zealand evaluating hoof conformation, lameness, or how we can best maintain a normally structured hoof and minimise lameness in commercially housed dairy goats. The overarching aim of this thesis was to examine the hoof conformation and gait of New Zealand dairy goats and to evaluate how these factors are impacted by hoof trimming. Specifically, I aimed to develop and validate a hoof conformation assessment for use in dairy goats, and to develop a reliable gait scoring system that would allow detection of an uneven gait as a potential precursor to clinical lameness. Furthermore, I aimed to use these methods to evaluate the immediate impacts of hoof trimming and the longer-term impacts of early life hoof trimming and subsequent trimming frequency on anatomical (e.g., hoof conformation, joint positions, hoof growth) and behavioural (e.g., lying behaviour, gait) variables. The hoof conformation assessment was determined to be reliable following considerable training of observers; both the objective measures and subjective scores could be used to accurately assess aspects of hoof conformation from photographs. As the subjective scores are less time-consuming and do not require technical equipment, I suggest they should be trialed for on-farm use. A reliable 5-point gait scoring system was developed in a controlled setting at the AgResearch Goat Research Facility. It included an “uneven gait” category, allowing identification of goats which may be predisposed to developing clinical lameness. However, whether it is feasible to detect an uneven gait from live observations on commercial farms is still to be determined. In an observational study conducted on 16 farms (n = 1099 goats; mean ± SD: 64 ± 9 goats/farm), goats that had not been trimmed prior to first mating (8.0 ± 0.70 months) had greater odds of poor hind hoof conformation at that time compared with goats on farms that had already trimmed prior to mating. In the longer term, goats on farms that had not trimmed before first kidding (14.8 ± 0.86 months) had greater odds of having dipped heels on the hind hooves at the end of second lactation (34.1 ± 0.90 months). In contrast, in a controlled experimental study conducted on one farm (n = 80 goats), only minor effects of early life trimming (before first kidding) on hoof conformation were found, and these were not consistent at assessments completed at the end of the first (13 months) and second lactations (25 months). In the experimental study, as poor conformation was observed in both the early and late trimmed treatments, it suggests that the subsequent hoof trimming (3 times per year) was not frequent enough to prevent overgrowth; the early life trimming treatment was not effective at this trimming frequency. In the observational study, trimming frequency following first kidding had no observable effects on hoof conformation. However, differences in the housing environment and management may be strongly impacting hoof conformation across the 16 farms. In the short term, immediate beneficial effects of hoof trimming were observed in the experimental study, with aspects of hoof conformation and joint positions restored to more anatomically correct shapes and positions. There was also some evidence of a transient effect of trimming on lying behaviour, with lying time increasing the day after hoof trimming at 3 out of 4 assessments over the first two years of life. An increase in lying time may be indicative of a pain response. However, daily lying behaviour was highly variable so should be interpreted with caution. High proportions of dipped heels, misshaped claws and splayed claws, particularly in the hind hooves, were recorded on 16 farms in the observational study and before trimming in the goats on the experimental study. Interestingly, on the latter farm, the prevalence of clinical lameness (scored from videos) in the same goats was lower than expected over the 2-year study period, though prevalence of an impaired gait (either uneven gait or clinical lameness) peaked after both kidding events. In addition, the rate of hoof growth changed across the goats’ first two years of life, slowing when the goats were in kid. Overall, my findings suggest that the trimming regimes evaluated in these studies were not adequate to prevent poor hoof conformation in goats housed in indoor environments that do not promote hoof wear. In order to achieve good conformation and long-term hoof health, dairy goat hoof management strategies should include consideration of the timing of first hoof trimming and subsequent trimming frequency, as well as providing an environment that promotes hoof wear.