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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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    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.
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    Epidemiological studies of bovine digital dermatitis in pasture-based dairy system in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Sciences at Massey University, Palmerston North, New Zealand
    (Massey University, 2019) Yang, Danchen
    Bovine digital dermatitis (BDD) is an infectious disease of the feet of cattle. Worldwide, it is one of the most commonly observed foot diseases on many dairy farms, and is the most important infectious cause of lameness in cattle in confined dairy system. Although BDD is generally less common in pasture-based dairy system it can still cause significant production losses and welfare issues, in such systems. This thesis contains seven original research works covering the epidemiological aspects of BDD in pasture-based cattle in New Zealand. Firstly, cross-sectional and longitudinal data obtained from Taranaki were analysed to identify the factors (including climate) associated with the disease. This was followed by a large scale cross-sectional study covering four regions in New Zealand looking at the prevalence of and risk factors for BDD. A longitudinal study was then undertaken on three farms in order to collect disease data (including BDD lesion type) over a lactation. Using this dataset, a deterministic compartment model was built to study the transmission dynamics of BDD within a dairy herd in New Zealand. Along with these large studies, two small validation studies were also carried out. The first study evaluated the agreement between two trained BDD observers in determining BDD presence/ absence in digital photographs, while the second one evaluated the reliability of clinical examination of BDD lesions in the milking parlour without prior washing of the animals’ feet. This work suggests that BDD has spread widely across New Zealand, although it has yet to reach the West Coast. In the four regions where BDD was identified, true between herd prevalences varied by region (from ~ 40% to > 65%). Furthermore, although BDD was found in many herds, true cow level prevalence was low in all affected regions, being generally less than 4% in affected herds. Several biosecurity related management practices were repeatedly identified as factors associated with increased BDD prevalence at both the herd and cow level. These included mixing heifers with animals from other properties; purchasing heifers for replacement and using outside staff to treat lame cows. In addition to the identified management practices, climate (rainfall and soil temperature) was also found to have had a significant association with the prevalence of BDD. These studies used examination in the milking parlour as the method of identifying BDD lesions. This method while the best method of lesion detection for large scale studies is not perfect. It generally requires that feet are washed prior to examination, as lesions masked by dirt are difficult to identify. Our study quantified the effect, under New Zealand conditions, of feet washing prior to examination finding sensitivities of 0.34 (95% credible interval [CrI]: 0.088-0.69) and 0.63 (95%CrI: 0.46- 0.78) for pre- and post-washing, respectively. There was a 93.95% probability that the sensitivity of examination post-washing was greater than that prewashing. Limited information on the reliability of examination in the milking parlour prompted comparison of two trained observers using digital photographs. Agreement between the two observers was good; we could be 75% sure that the two observers had almost perfect agreement and 95% sure the two observers had at least substantial agreement. It is crucial that since examination in the milking parlour is not a perfect reference test for detecting BDD lesions that when estimating prevalence, the sensitivity and specificity of this method is factored into the analysis. This is often achieved using an approach based on the binomial distribution. However, as the dairy herd is a finite population and the sampling of animals for BDD lesion is effectively sampling without replacement, the correct distribution to use is the hypergeometric one. This is computationally complex so the Bayesian superpopulation approach was developed to allow continued use of the binomial distribution. The superpopulation approach was used to estimate prevalence in this thesis, one of the first uses of this approach in the veterinary field. The appearance of BDD in New Zealand is different from that elsewhere. Most lesion have been observed are small grey, rubbery lesions which may or may not have thickened, darker edges. Less commonly larger, more proliferative lesions can also be found. Red active lesions are extremely rare. Post-treatment lesions are not a feature of the disease in New Zealand as lesions are treated only very rarely. Thus modelling approach used a BDD score system which focuses on early stage of BDD. This found that in infected dairy herds, although BDD prevalence will tend to increase year-on-year it is likely to remain relatively low (<18%) even after 10 years of within-herd transmission. It is likely that the low transmission rate during the late lactation (model assumption) results in more cases resolving than developing during this period and therefore results in the low prevalence of infectious cattle at the start of each subsequent lactation. Cattle with larger, more proliferative lesions had a stronger influence on the establishment and maintenance of DD than cattle with small lesions highlighting the importance of targeting these animals for intervention.
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    Anatomical studies of claw conformation in New Zealand dairy cattle : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science, Massey University, Palmerston North, New Zealand
    (Massey University, 2014) Laven, Linda Jean
    The aim of the studies reported in this thesis was to extend our current knowledge on estimating and monitoring claw conformation under New Zealand conditions. Initially post mortem material was used to: (1) evaluate the utility of claw volume estimation with data from cull dairy cows; (2) validate the use of a portable ultrasound machine in the estimation of internal claw dimensions; and (3) apply morphometry to quantify vascular change in histological sections from the collected claw material. Analysis of the relationship between claw volume and hoof conformation revealed differences between the claws of dairy cattle used for this study and those of beef cattle which had been used previously. This necessitated the development of a different predictive model for dairy cattle which was subsequently used in the live animal studies. Validation of ultrasound estimates for sole and soft tissue thickness against calliper measurements in the sectioned claw, found that the portable machine used accurately estimated mean distance to distal phalanx (DP) and was thus suitable for categorising claws as having thin, marginal or adequate sole thickness. Morphometrical techniques were successfully applied to sections from frozen claw material; the ratio of vessel lumen area to overall vessel area was found to vary depending on site, claw and overall vessel size. No relationship was found between the ratio and claw horn haemorrhages, but the level of such lesions was low in the animals available for analysis. Subsequently, selected conformation traits were assessed on-farm in two consecutive cohorts of first lactation heifers. Some variables were identified as being useful to evaluate conformational change within a pasture-based system. These demonstrated dynamic change over the course of lactation. However, fluctuation in these variables at pasture means that any intervention study would need to have a greater impact on the claw than the variations produced by the background environment. Other variables showed stability over lactation and between years of study, and are therefore potentially suited to the investigation of claw size in relation to the development of lesions and lameness. In Year 1, ultrasound estimates of DP were recorded as a proxy for sole thickness. Values decreased significantly after calving to a nadir at approximately Day 110. The change in DP between Days 10 and 110 was associated with the initial value of DP on Day 10. The study concluded that thin soles increased in depth while thick soles wore to become thinner, indicating that heifers with thinner soles were able to accommodate to the changes occurring around and after calving and that the response of the claw to encountering tracks, collecting yards and milking parlours is not simply an increase in net wear. In Year 2, a novel method to capture changes in heel conformation was successfully trialled. Non-weight bearing heel length was found to alter rapidly after calving while other measures responded slowly in comparison and suggested extended monitoring was advisable. The on-farm studies established that, for most conformational variables, there is value in recording information from all four claws of the hind feet in a pasture based system.
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    A study of foot abscess in sheep : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University
    (Massey University, 1981) West, David Michael
    A study was made of various aspects of 53 naturally occurring cases of foot abscess in sheep. Radiographic techniques were used to follow the progress of the lesion and from this, and a study of the anatomy of the digits, it was concluded that foot abscess of sheep could be defined as an infection of the distal interphalangeal joint. For this reason the term 'foot abscess' was considered to be preferable to the term 'infective bulbar necrosis' (Roberts et al., 1968). Support was given to the contention of Roberts et al.(1968) that Fusobacterium necrophorum and Corynebacterium pyogenes are the causative organisms of foot abscess. Both organisms were frequently isolated from naturally occurring cases, and an identical condition was reproduced in seven sheep by inoculating a mixture of F. necrophorum and C. pyogenes organisms into the distal interphalangeal joint. It appeared likely that relatively greater numbers of either organism in pure culture were required to reproduce foot abscess by this means, than by using a mixture of the two organisms. To help evaluate the significance of foot abscess to New Zealand sheep farmers, a postal survey of New Zealand Romney sheep breeders was conducted. Foot abscess was reported to occur in 270 (77 percent) of the 351 respondents' flocks, but the incidence of foot abscess within a flock was low. Foot abscess was considered an important disease by sheep farmers because of the unexpected nature of outbreaks at critical times in the farming calendar, and the unsatisfactory nature of treatment and prevention. The F. necrophorum vaccine was used by a third of the farmers that reported having cases of foot abscess in their flocks and many farmers were either dissatisfied with, or unsure of its effectiveness. The attack rate of foot abscess was reported to be higher for rams than for ewes. A possible explanation for this was advanced following the investigation of an outbreak of ovine interdigital dermatitis and foot abscess affecting 100 individuals out of 300 young rams on a Perendale stud property. From a study of the anatomy of the digits it was concluded that the distal interphalangeal joint of sheep was vulnerable to infection or trauma on the interdigital aspect where the joint capsule protruded above the coronary border of the hoof as the dorsal and volar pouches. Foot abscess was reproduced in 39 digits of 20 sheep, following interdigital tissue damage by the application of liquid nitrogen to the interdigital skin, combined with the exposure of the feet to wet, faeces-contaminated conditions. It was suggested that this simulated what happens in natural outbreaks of ovine interdigital dermatitis and foot abscess. Ovine interdigital dermatitis responded readily to the combined therapeutic measures of dry surroundings, formalin foot bathing and selected antibiotic therapy. In contrast, once infection became established in the distal interphalangeal joint (foot abscess), the above treatment was no longer effective. Permanent joint damage with deformity was inevitable, but the effects of this was reduced if the axial collateral ligaments remained intact. The foot healed sufficiently to allow for adequate locomotion after a period of about two months. It was possible, using radiographic techniques to assess if the distal interphalangeal joint was infected, the approximate duration of the joint infection, and the likely degree of permanent damage and deformity.