A within farm clinical trial to compare two treatments (parenteral antibacterials and hoof trimming) for sheep lame with footrot

From observational studies, farmers who use parenteral antibacterials to promptly treat all sheep with footrot (FR) or interdigital dermatitis (ID) have a prevalence of lameness of <2% compared with a prevalence of 9% lameness reported by farmers who treat lame sheep by trimming affected feet. We tested the hypothesis that prompt treatment of sheep lame with naturally developing FR or ID with parenteral and topical antibacterials reduces the prevalence and incidence of lameness with these conditions compared with less frequent treatment with trimming of hoof horn and applying topical antibacterials. A further hypothesis was that reduction of ID and FR would improve productivity. A lowland sheep flock with 700 ewes was used to test these hypotheses in an 18-month within farm clinical trial with four groups of ewes: two intervention and two control. The duration and severity of lameness was used to categorise sheep into three weighted scores of lameness (WLS): never lame (WLS0), mildly lame/lame for <6 days (WLS1) and severely or chronically lame (WLS2). The intervention reduced the prevalence of lameness due to FR and ID in ewes and lambs and the incidence of lameness in ewes. The WLS was also significantly lower in sheep in the intervention groups. Ewes with a higher WLS were subsequently significantly more likely to have a body condition score <2.5 and to have lame lambs. Significantly more ewes lambed and successfully reared more lambs that were ready for slaughter at a younger age in the intervention versus control groups. There was an increase in the gross margin of £630/100 ewes mated in the intervention group, including the cost of treatment of £150/100 ewes mated. We conclude that prompt parenteral and topical antibacterial treatment of sheep lame with ID and FR reduced the prevalence and incidence of these infectious conditions and led to improved health, welfare and productivity

A case report of lameness in two dairy goat herds: a suspected combination of nutritional factors concurrent with treponeme infection

Background: Two dairy goat farms with high level of lameness in lactating animals were presented for further investigation. Farm 1 and Farm 2 presented with 37 and 67 % morbidity, respectively. Both farms had an all year round indoor system, feeding ad libitum concentrate with forage available at all times. Case presentation: The lameness was found to be based in the foot. Previous treatments consisting of biweekly footbathing with zinc sulphate, spraying lesions with oxytetracycline spray and packing lesions with copper crystals on a single occasion and single injections with long acting oxytetracycline had not been successful. Mild cases had signs of haemorrhaging in the white line or on the sole of the foot. Moderate cases showed under running of the wall horn or small areas of exposed sole corium. Severe cases would consist of horn or wall separation with the corium exposed and infected. In extreme cases only the wall horn of the claw remained, with a large area of necrotic tissue in the centre and no healthy corium visible. Only one animal was seen to have interdigital lesions. Polymerase chain reaction (PCR) and culture of swabs taken from exposed corium and the interdigital space were negative for Dichelobacter nodosus but PCR for treponemes were positive in both the adults and the youngstock tested. Due to the high level of concentrate in the diet of these goats, nutrition was thought to contribute to the problem. Transcutaneous rumen fluid samples were taken and pH was measured on both farms, with 35 % of the samples below pH value 5.5. Conclusion: No definite diagnosis could be made. However, the results suggest both treponemes and nutrition play a role in the aetiology of the lameness. The initial sole or wall horn lesions were thought to be secondarily infected by treponemes. Further investigation is needed to definitively diagnose the cause and contributing factors for this lamenes

How does reviewing the evidence change veterinary surgeons' beliefs regarding the treatment of ovine footrot? A quantitative and qualitative study

Footrot is a widespread, infectious cause of lameness in sheep, with major economic and welfare costs. The aims of this research were: (i) to quantify how veterinary surgeons’ beliefs regarding the efficacy of two treatments for footrot changed following a review of the evidence (ii) to obtain a consensus opinion following group discussions (iii) to capture complementary qualitative data to place their beliefs within a broader clinical context. Grounded in a Bayesian statistical framework, probabilistic elicitation (roulette method) was used to quantify the beliefs of eleven veterinary surgeons during two one-day workshops. There was considerable heterogeneity in veterinary surgeons’ beliefs before they listened to a review of the evidence. After hearing the evidence, seven participants quantifiably changed their beliefs. In particular, two participants who initially believed that foot trimming with topical oxytetracycline was the better treatment, changed to entirely favour systemic and topical oxytetracycline instead. The results suggest that a substantial amount of the variation in beliefs related to differences in veterinary surgeons’ knowledge of the evidence. Although considerable differences in opinion still remained after the evidence review, with several participants having non-overlapping 95% credible intervals, both groups did achieve a consensus opinion. Two key findings from the qualitative data were: (i) veterinary surgeons believed that farmers are unlikely to actively seek advice on lameness, suggesting a proactive veterinary approach is required (ii) more attention could be given to improving the way in which veterinary advice is delivered to farmers. In summary this study has: (i) demonstrated a practical method for probabilistically quantifying how veterinary surgeons’ beliefs change (ii) revealed that the evidence that currently exists is capable of changing veterinary opinion (iii) suggested that improved transfer of research knowledge into veterinary practice is needed (iv) identified some potential obstacles to the implementation of veterinary advice by farmers

Detection and diversity of a putative novel heterogeneous polymorphic proline-glycine repeat (Pgr) protein in the footrot pathogen Dichelobacter nodosus

Dichelobacter nodosus, a Gram-negative anaerobic bacterium, is the essential causative agent of footrot in sheep. Currently, depending on the clinical presentation in the field, footrot is described as benign or virulent; D. nodosus strains have also been classified as benign or virulent, but this designation is not always consistent with clinical disease. The aim of this study was to determine the diversity of the pgr gene, which encodes a putative proline-glycine repeat protein (Pgr). The pgr gene was present in all 100 isolates of D. nodosus that were examined and, based on sequence analysis had two variants, pgrA and pgrB. In pgrA, there were two coding tandem repeat regions, R1 and R2: different strains had variable numbers of repeats within these regions. The R1 and R2 were absent from pgrB. Both variants were present in strains from Australia, Sweden and the UK, however, only pgrB was detected in isolates from Western Australia. The pgrA gene was detected in D. nodosus from tissue samples from two flocks in the UK with virulent footrot and only pgrB from a flock with no virulent or benign footrot for >10 years. Bioinformatic analysis of the putative PgrA protein indicated that it contained a collagen-like cell surface anchor motif. These results suggest that the pgr gene may be a useful molecular marker for epidemiological studies

Ovine pedomics : the first study of the ovine foot 16S rRNA-based microbiome

We report the first study of the bacterial microbiome of ovine interdigital skin based on 16S rRNA by pyrosequencing and conventional cloning with Sanger-sequencing. Three flocks were selected, one a flock with no signs of footrot or interdigital dermatitis, a second flock with interdigital dermatitis alone and a third flock with both interdigital dermatitis and footrot. The sheep were classified as having either healthy interdigital skin (H), interdigital dermatitis (ID) or virulent footrot (VFR). The ovine interdigital skin bacterial community varied significantly by flock and clinical condition. The diversity and richness of operational taxonomic units was greater in tissue from sheep with ID than H or VFR affected sheep. Actinobacteria, Bacteriodetes, Firmicutes and Proteobacteria were the most abundant phyla comprising 25 genera. Peptostreptococcus, Corynebacterium and Staphylococcus were associated with H, ID and VFR respectively. Sequences of Dichelobacter nodosus, the causal agent of ovine footrot, were not amplified due to mismatches in the 16S rRNA universal forward primer (27F). A specific real time PCR assay was used to demonstrate the presence of D. nodosus which was detected in all samples including the flock with no signs of ID or VFR. Sheep with ID had significantly higher numbers of D. nodosus (104-109 cells/g tissue) than those with H or VFR feet

Albumin Extravasation During Surgery

This thesis is concerned with the measurement of changes in the circulation during the period of surgery. A loss of albumin from the circulation is to be expected from observations and experiments made in the postoperative period. In this thesis a sensitive measurement technique is described which allows extravasation of albumin to be studied in patients undergoing elective surgery. Radio-isotope labelled albumin and radio-isotope labelled red cells are injected; the ratio between the two is not affected by blood loss or infusion and the ratio is therefore used as a measure of albumin extravasation. To measure the relative loss of albumin from the circulation the isotopes were administered some days prior to surgery to allow distribution and equilibration of the albumin. To measure the rate of loss of albumin (capillary permeability) the isotopes were administered at the time of surgery. The results indicate that major surgery under general anaesthesia is accompanied by a loss of albumin from the circulation, an increased capillary permeability to albumin and a fall in plasma volume that is greater than can be explained on the basis of blood loss and greater than would be expected on the basis of the reduction in red cell volume. The results suggest that patients who receive only glucose and salt solutions intravenously during major surgery will usually suffer a contraction in their blood volumes unless unacceptably large volumes of fluid are infused

Mechanisms and Management of Breathlessness in Chronic Heart Failure

Background: The pathophysiology of dyspnoea (‘breathlessness’) is poorly understood and treatment options limited. This is particularly true for heart failure in which dyspnoea is a cardinal symptom, even when the heart failure is optimally managed. This thesis aims to untangle mechanisms and utilise this knowledge to optimise heart failure management. It focuses on the potential of nebulised furosemide as an adjunct treatment, given its excellent safety record and existing evidence that it modulates dyspnoea via direct action on lungs. Methods: A multi-dimensional questionnaire was used to survey the prevalence of dyspnoea in the heart failure community. A randomised, double blind, placebo-controlled crossover trial (RCT) was then performed in healthy participants to determine the specific components of dyspnoea that are relieved by the action of furosemide on the lungs. This study led to the design of a feasibility RCT in patients with heart failure using the visual analogue scale (VAS) ratings of the ‘air hunger’ (AH) component of dyspnoea as the primary outcome measure. The RCT itself; i) addressed other issues that could account for variability in relief seen in previous studies, ii) explored blood biomarkers of heart failure in relation to dyspnoea and iii) provided guidance for future definitive clinical trials. Results: 1) 47% of patients experienced dyspnoea in the community. Dyspnoea-12 scores correlated with New York Heart Association class, with many in class III experiencing dyspnoea at rest. 2) Nebulised furosemide specifically relieved AH induced in healthy participants but did not affect the 'work/effort' component. Relief was only with nebulised, not intravenous furosemide. 3) Breathing furosemide quickly or slowly did not alter dyspnoea relief, but ventilation was not matched. 4) Cardiopulmonary exercise testing (CPET) produced an average VO2peak of 54±15% predicted, with a measurable anaerobic threshold in 73% of tests and raised dyspnoea to 42±19%VAS. 5) Nebulised furosemide resulted in no significant improvements in exercise capacity. 6) Cardiac biomarkers increased appropriately and returned to baseline within 1 hour of exercise. The maximal absorption efficiency of nebulised furosemide was 2%. Conclusion: 1) Dyspnoea is a prevalent symptom in heart failure, comparable to chronic obstructive pulmonary disease. The NYHA classification may require clarification regarding presence of breathlessness at rest. 2) Relief of dyspnoea with nebulised furosemide occurs via a mechanism within the lungs and should be targeted at those in whom ‘air hunger’ predominates. 3) CPET is a feasible method for dyspnoea assessment in heart failure. 4) Fully powered RCT of nebulised furosemide in heart failure are warranted taking on board the preliminary information gathered in this thesis to optimise treatment effect

A Spaetzle-like role for Nerve Growth Factor β in vertebrate immunity to Staphylococcus aureus

Many key components of innate immunity to infection are shared between Drosophila and humans. However, the fly Toll ligand Spaetzle is not thought to have a vertebrate equivalent. We have found that the structurally related cystine-knot protein, nerve growth factor β (NGFβ), plays an unexpected Spaetzle-like role in immunity to Staphylococcus aureus infection in chordates. Deleterious mutations of either human NGFβ or its high-affinity receptor tropomyosin-related kinase receptor A (TRKA) were associated with severe S. aureus infections. NGFβ was released by macrophages in response to S. aureus exoproteins through activation of the NOD-like receptors NLRP3 and NLRC4 and enhanced phagocytosis and superoxide-dependent killing, stimulated proinflammatory cytokine production, and promoted calcium-dependent neutrophil recruitment. TrkA knockdown in zebrafish increased susceptibility to S. aureus infection, confirming an evolutionarily conserved role for NGFβ-TRKA signaling in pathogen-specific host immunity