Ovine footrot: A review of current knowledge.

Footrot is a contagious foot disease mainly affecting sheep. It is caused by the Gram-negative anaerobic bacterium Dichelobacter nodosus. Warm, wet environmental conditions favour development of footrot, and under perfect conditions, it takes just 2-3 weeks from infection to manifestation of clinical signs. Affected sheep show lameness of various degrees and often graze while resting on their carpi. Local clinical signs vary in severity and extent from interdigital inflammation (benign footrot) to underrunning of the complete horn shoe in advanced stages of virulent footrot. Laboratory diagnosis ideally involves collection of four-foot interdigital swab samples followed by competitive real time PCR, allowing for detection of the presence of D. nodosus and differentiation between benign and virulent strains. Laboratory-based diagnostics at the flock level based on risk-based sampling and pooling of interdigital swab samples are recommended. The list of treatment options of individual sheep includes careful removal of the loose undermined horn, local or systemic administration of antimicrobials, systemic administration of non-steroidal anti-inflammatories (NSAIDs) and disinfectant footbathing. Strategies for control at the flock level are manifold and depend on the environmental conditions and the procedures traditionally implemented by the respective country. Generally, measures consist of treatment/culling of infected sheep, vaccination and prevention of reinfection of disease-free flocks. Gaining deeper insight into the beneficial effects of NSAIDs, screening for eco-friendly footbath solutions, developing better vaccines, including the development of a robust, reproducible infection model and elucidation of protective immune responses, as well as the elaboration of effective awareness training programs for sheep farmers, are relevant research gaps.

Tolio: Foot Rot in Grand Canyon River Runners.

Treating skin disorders in wilderness settings is often challenging. In this report we describe common skin conditions affecting the feet of river runners on the Colorado River in Grand Canyon National Park. These conditions are frequently referred to by river runners with a catchall term, "tolio." Several skin disorders have been identified as components of tolio, with the most prevalent currently being pitted keratolysis. We present a case of pitted keratolysis in a river guide occurring during a multiday river trip, where treatment can be difficult. Prevention is often more important.

[Footbath as treatment of footrot in sheep. Current -situation on Swiss sheep farms]. / Klauenbad zur Bekämpfung der ­Moderhinke bei Schafen. Eine Bestandes­aufnahme bei Schweizer Schafhaltern.

INTRODUCTION: Footrot in sheep should be eradicated in Switzerland in the future. Based on scientific findings, this can be achieved with disinfectant footbaths. It is unknown how many sheep farmers are already using this means and how it is used. The current study evaluated the farm operation, the design of the footbath, the use of disinfectants and footbath with a written survey of a representative sample of all sheep farmers. The sample population was selected randomly, however stratified by language region and herdsize to control for differences between these groups. 45.3% (n=1134) of the distributed questionnaires were received for evaluation. On average 32.8% of the respondents used a footbath. Even on large farms (> 50 animals), which were more frequently affected by footrot, a footbath was available only in 52.6% of the farms in the French-speaking part and 67.7% in the German/Italian speaking part of Switzerland. The footbaths were correctly applied in most respects (e.g., pre-claw cleaning, liquid level and concentration of disinfectants, time in the footbath, post-bath drying phase) in the current study. Most commonly mobile plastic baths were in use. The disinfectants used were mainly formalin, copper and zinc sulfate. The incorrect disposal of the heavy-metal containing copper and zinc sulfate solutions was identified as an important problem: In 59% of the sheep farms the remaining footbath solutions were disposed in the slurry pit or manure storage. In summary the current study recommends (i) to motivate sheep farmers to use a footbath for the treatment and prevention of footrot, and (ii) to replace the currently used disinfectants with substances that are non-toxic to humans, animals and the environment.

INTRODUCTION: Le piétin du mouton doit être, à l'avenir, combattu sur l'ensemble du territoire suisse. Sur la base des connaissances scientifiques, cela peut être fait avec un bain désinfectant pour les onglons. On ignore combien d'éleveurs utilisent déjà cette mesure et comment elle est utilisée. On a cherché, au moyen d'un sondage d'un échantillon représentatif d'éleveurs de moutons, à obtenir la réponse à quatre groupes de questions sur l'exploitation, la construction du pédiluve, l'utilisation de désinfectants et l'usage du bain des onglons. La stratification concernant la région linguistique d'une part et la taille du troupeau d'autre part, permettait de donner la meilleure image possible dans l'échantillon. Avec l'évaluation de 1134 des questionnaires évaluables (45,3% de ceux initialement envoyés) ont a constaté qu'en moyenne 32,8% seulement des exploitants utilisaient un bain des onglons. Même avec les grands troupeaux avec > 50 animaux, qui sont donc plus fréquemment touchés par le piétain, seuls 52,6% des exploitants francophones respectivement 67,7% des germanophones ou des italophones disposent d'un bain. D'autre part, les utilisateurs de bain des onglons appliquent dans la plupart des cas correctement les aspects principaux (par ex.: prélavage des onglons, niveau de liquide et concentration des désinfectants, temps passé dans le bain, phase de séchage après le bain). Les installations les plus communément utilisées étaient les bains mobiles en plastique. La formaline, le sulfate de cuivre et de zinc étaient principalement utilisés comme désinfectants. On constatait un grand manque quant à l'élimination des désinfectants, en particulier des solutions contenant des métaux lourds comme le cuivre ou le zinc. Ainsi, 59,4% des éleveurs ont déclaré jeter les liquides dans la fosse à lisier ou sur le tas de fumier. Les constatations principales sont donc: (i) que les éleveurs de moutons devraient être motivés à utiliser un bain des onglons pour le traitement et la prévention du piétain, et (ii) que le remplacement des désinfectants actuellement utilisés par des substances non toxiques pour l'homme, l'animal et l'environnement est absolument nécessaire.

Comparison of footbathing and vaccination to control ovine footrot in an experimentally infected flock.

OBJECTIVE: Compare footbathing and vaccination for control of footrot during a transmission period in a sheep flock deliberately infected with multiple strains of Dichelobacter nodosus. METHODS: The strains included a known virulent strain, a benign strain and several intermediate strains. The resulting footrot was clinically intermediate. A total of 1450 Polwarth sheep aged 1-3 years were allocated to one of five treatment groups: untreated, weekly walkthrough zinc sulfate footbathing, 1-hour stand-in Footrite® footbathing every 3 weeks, vaccination with a commercial multivalent whole-cell vaccine and vaccination with a novel recombinant DNA fimbrial vaccine. There were four replicates, in four paddocks. RESULTS: Of the untreated animals, 76% had footrot. Footbathing, either weekly or every 3 weeks, restricted the prevalence to 6/283 (2%; 97% effective) and 18/275 (6.5%; 91% effective), respectively. This was significantly lower than the prevalence in either the untreated or vaccinated group (P < 0.001). Weekly footbathing resulted in significantly fewer affected sheep than footbathing for 1 h every 3 weeks (P < 0.05). Vaccination with either whole-cell or recombinant vaccines significantly (P < 0.001) reduced the prevalence ((142/280 (51%; 33% effective), 114/278 (41%; 46% effective) respectively), with the recombinant vaccine superior (P < 0.05) to whole-cell vaccination. Significantly (P < 0.05) fewer 1-year-old sheep had footrot than older sheep. A single Footrite treatment reduced the prevalence to 12% (53/445) compared with a prevalence of 57% (27/47) for untreated sheep (79% effective). CONCLUSION: In this study footbathing was more effective than vaccination at controlling and treating multistrain footrot.

Relationship between the likelihood of footrot elimination from a flock and the virulence of the strain of Dichelobacter nodosus present.

OBJECTIVE: To assess ability to eliminate different strains of footrot in sheep using inspection and culling of affected sheep. METHODS: A flock of 1417 Polwarth sheep that had deliberately been infected with seven different strains of Dichelobacter nodosus and undergone different control measures prior to eradication, including zinc sulfate footbathing and vaccination, were subjected to visual foot inspection on a number of occasions. Sheep identified as infected or having any foot abnormalities were removed from the flock at each inspection. The experiment had three replicates and a small number of untreated control animals. Sheep were examined following the inspections to assess the effectiveness of elimination and additional measures were implemented in two of the three replicates in an attempt to eliminate all strains of D. nodosus. RESULTS: Three strains of D. nodosus were apparently successfully eliminated from all replicates (strains A, E and H). Strains B and C were detected in one replicate each, despite additional inspections. The three stains that were eliminated were the more virulent strains and the two strains that remained were the least virulent. No assessment could be made on a further two strains. CONCLUSIONS: The application of a rigorous inspection and culling program resulted in the elimination of the more virulent D. nodosus strains, but did not result in the elimination of all D. nodosus strains on all occasions.

[Claw infections in sheep - treatment options in veterinary practice, with special emphasis on ovine footrot treatment. - An update]. / Klaueninfektionen beim Schaf ­ Therapiemöglichkeiten in der tierärztlichen Praxis unter besonderer Berück sichtigung der Moderhinkebekämpfung.

Infectious causes of lameness in sheep remain of considerable clinical importance. Because of the availability of newly licensed drugs, important changes in therapy options, particularly for ovine footrot, have occurred. This paper provides an overview of common and rarer infectious causes of lameness in sheep, and presents a detailed review of recent advances in research regarding the aetiology, diagnosis, prevention, treatment and control of ovine foot rot. Despite the recent release of several antibiotics licensed for the treatment of footrot in sheep, the use of footbaths following the cascade of regulations remains a crucial part of many integrated treatment and control programmes. The sustainable control of foot rot requires recent advances in science to be put into practice, with tailor-made control programmes for each individual farm. The article presents various treatment options and potential routes of control and eradication.

Associations between sheep farmer attitudes, beliefs, emotions and personality, and their barriers to uptake of best practice: The example of footrot.

There is interest in understanding how farmers' behaviour influences their management of livestock. We extend the theory of planned behaviour with farmers attitudes, beliefs, emotions and personality to investigate how these are associated with management of livestock disease using the example of footrot (FR) in sheep. In May 2013 a one-year retrospective questionnaire was sent to 4000 sheep farmers in England, requesting data on lameness prevalence, management of footrot, farm/flock descriptors, and farmer-orientated themes: barriers to treating footrot, opinions and knowledge of footrot, relating to other people and personality. Principal component analysis (PCA) was used to make composite variables from explanatory variables and latent class (LC) analysis was used to subgroup farmers, based on nine managements of FR. Associations between LC and composite variables were investigated using multinomial logistic regression. Negative binomial regression was used to investigate associations between the proportion of lame sheep and composite and personality variables. The useable response rate was 32% and 97% of farmers reported having lame sheep; the geometric mean prevalence of lameness (GMPL) was 3.7% (95% CI 3.51%-3.86%). Participants grouped into three latent classes; LC1 (best practice-treat FR within 3days of sheep becoming lame; use injectable and topical antibiotics; avoid foot trimming), 11% farmers), LC2 (slow to act, 57%) and LC3 (slow to act, delayed culling, 32%), with GMPL 2.95%, 3.60% and 4.10% respectively. Farmers who reported the production cycle as a barrier to treating sheep with FR were more likely to be in LC2 (RRR 1.36) than LC1. Negative emotions towards FR were associated with higher risk of being in LC2 (RRR 1.39) than LC1. Knowledge of preventing FR spread was associated with a lower risk of being in LC2 (RRR 0.46) or LC3 (RRR 0.34) than LC1. Knowledge about FR transmission was associated with a lower risk of being in LC3 (RRR 0.64) than LC1. An increased risk of lameness was associated with the production cycle being a barrier to treating sheep with FR (IRR 1.13), negative emotions towards FR (IRR 1.13) and feelings of hopelessness towards FR (IRR 1.20). Conscientiousness (IRR 0.95) and understanding the importance of active control of lameness (IRR 0.76) were associated with reduced risk of lameness. We conclude that emotions and personality are associated with differences in farmer management of FR and prevalence of lameness. Further understanding how personality and emotions influence change in behaviour is key to increasing uptake of new information.

Elimination of virulent strains (aprV2) of Dichelobacter nodosus from feet of 28 Swiss sheep flocks: A proof of concept study.

Virulent ovine footrot caused by Dichelobacter nodosus is an endemic disease worldwide. It is associated with severe pain, impaired animal welfare and economic losses. The competitive real-time PCR for the differentiation of virulent aprV2 and benign aprB2 strains of Dichelobacter nodosus provides an objective, rapid and sensitive diagnostic tool for footrot surveillance, especially as it enables early detection of subclinical carriers of virulent strains. The aim of this study was to evaluate the feasibility of complete elimination of Dichelobacter nodosus strains carrying the aprV2 gene from sheep flocks. The treatment protocol was based on careful removal of loose and severely overgrown claw horn, weekly stand-in foot baths of the entire flock for 10 min per sheep, using a 10% zinc sulphate disinfectant solution, clinical and PCR follow-up and isolation or culling of non-responders. Dichelobacter nodosus strains carrying the aprV2 gene were successfully eliminated from the feet of the sheep of all 28 flocks (100%) participating in the study within 6-19 weeks of weekly foot bathing. A strong correlation between the length of time for weekly foot bathing to eliminate the virulent strains and the within-flock prevalence of clinical footrot at the beginning was observed (rho, 0.68; P <0.001). A statistically significant correlation was not detected between flock size and the length of time for weekly foot bathing (rho, 0.28; P = 0.14), or the prevalence of clinical footrot at study commencement (rho, -0.04; P = 0.82), respectively. In conclusion, a complete elimination of Dichelobacter nodosus strains carrying the aprV2 gene in sheep flocks was possible with a protocol based on careful trimming, weekly stand-in foot baths, and identification of infection using a specific PCR-test and isolation or culling of non-responders.

Investigation of immunity in sheep following footrot infection and vaccination.

Ovine footrot is a major disease affecting sheep welfare and production. The anaerobic Gram-negative bacterium Dichelobacter nodosus is the essential transmitting agent. Monovalent or bivalent vaccines induce high levels of D. nodosus antibodies and are the basis of several successful footrot treatment, control and eradication programs. Due to the rapid rate of disease transmission within a flock, the presence of therapeutic vaccination non-responders has major implications for a control program. The aim of this study was to assess the immunological basis of a therapeutic vaccination non-response. Sheep (n=120) were infected with D. nodosus in an artificial pen challenge. Once disease had established, animals were vaccinated with a serogroup specific D. nodosus fimbrial vaccine. Based on the response to therapeutic vaccination, animals were allocated into one of three groups: (i) TVNR where disease persisted despite vaccination (ii) non-diseased, where disease never established and (iii) TVR, where disease was established but resolved with vaccination. Factors related to both the innate and adaptive immune pathways were assessed. These included antigen-specific serum antibodies, interferon-γ, interleukin-10, proliferation of lymphocyte subsets and phagocytic activity of leukocytes. There was no significant difference between the three groups of sheep for any of these parameters. All three groups of sheep produced antibody in excess of a previously published minimum antibody titre required for protection. Opsonising activity in sera from the three groups of sheep was also not significantly different and phagocytic cells from sheep from all three groups were able to destroy D. nodosus intracellularly. These findings show that the measured systemic adaptive and innate immune responses were unlikely to be the cause of a therapeutic vaccination non-response. They also show that the accepted minimum protective titre may be incorrect and may need further examination.

Outbreak-specific monovalent/bivalent vaccination to control and eradicate virulent ovine footrot.

Footrot is a contagious disease of small ruminants which is caused by the bacterium Dichelobacter nodosus. In its virulent form there are severe economic losses and a very significant animal welfare issue. Sheep and goats can be vaccinated for treatment and prevention of the disease. There are 10 different serogroups of D. nodosus (A-I and M) and immunity is serogroup-specific. When all 10 serogroups are presented together in a vaccine, protection persists for only a few months due to "antigenic competition". Consequently we evaluated the use of sequential monovalent or bivalent vaccines to control/eliminate/eradicate virulent footrot in a longitudinal intervention study on 12 commercial farms in southeast Australia with flock sizes of approximately 1200-4200 sheep. Overall, virulent footrot was eradicated from 4 of the flocks, 2 of which had 2 serogroups, and the others 4 or 5 serogroups. Where there were only 1 or 2 serogroups (3 farms) the clinical response was rapid and dramatic; prevalence was reduced from 45 to 50% before vaccination to 0% (2 farms) or 0.4% (1 farm) after one round of vaccination. In the remaining 9 flocks there were more than 2 serogroups and successive bivalent vaccines were administered leading to eradication of virulent footrot on 2 farms over 4 years and control of the disease on all but 3 of the others. Of the latter farms, 1 discontinued, and 2 initially had poor response to vaccine due to misdiagnosis of serogroup 'M', which was previously unknown in Australia. Control was achieved after administration of a serogroup M vaccine. These results provide clear evidence for control, elimination and eradication of virulent footrot by outbreak-specific vaccination in Australia.

[Infectious causes of lameness in sheep - treatment options in veterinary practice]. / Infektiöse Lahmheiten beim Schaf - Therapiemöglichkeiten in der tierärztlichen Praxis.

Lameness in sheep induced by infectious agents can cause problems regarding animal welfare, diagnosis and treatment. Individual lame animals and lameness caused by systemic disease, but especially flock problems due to infectious causes of lameness, such as foot rot, can for various reasons pose a problem for veterinary treatment. The causes of lameness in sheep are described with a special focus on infectious flock problems, and the different treatment options such as foot trimming, foot baths and local and systemic antibiotic therapy as well as vaccination are discussed based on a review of recent international research. The limited choice of drugs licensed for use in sheep in Germany is highlighted. Treatment, therefore, often requires off-label use or the import of footbathing agents licensed in other European countries. The legal consequences of this lack of nationally licensed veterinary products in dealing with a "minor species" are discussed, with a final call for political solutions that will help improve this unsatisfactory situation.

[Legal aspects of the use of footbaths for cattle and sheep]. / Klauenbäder unter rechtlichen Aspekten.

Claw diseases pose a major problem for dairy and sheep farms. As well as systemic treatments of these illnesses by means of drug injection, veterinarians discuss the application of footbaths for the local treatment of dermatitis digitalis or foot rot. On farms footbaths are used with different substances and for various purposes. The author presents the requirements for veterinary medicinal products (marketing authorization and manufacturing authorization) and demonstrates the operation of the "cascade in case of a treatment crisis". In addition, the distinction between veterinary hygiene biocidal products and veterinary medicinal products and substances to care for claws is explained.

Footrot and interdigital dermatitis in sheep: farmer satisfaction with current management, their ideal management and sources used to adopt new strategies.

The aims of this research were to identify management practices that sheep farmers currently use to treat and prevent footrot in sheep and whether they consider that these are successful management tools and to find out how sheep farmers would ideally like to manage footrot in their flock. Over 90% of lameness in sheep in the UK is caused by Dichelobacter nodosus, which presents clinically as interdigital dermatitis (ID) alone or with separation of hoof horn (FR). A questionnaire was sent to 265 farmers to investigate their current management and their satisfaction with current management of the spectrum of clinical presentations of footrot. Farmers were also asked their ideal management of footrot and their interest in, and sources of information for, change. Approximately 160 farmers responded. Farmers satisfied with current management reported a prevalence of lameness < or = 5%. These farmers caught and treated lame sheep within 3 days of first seeing them lame, and treated sheep with FR and ID with parenteral antibacterials. Farmers dissatisfied with their management reported a prevalence of lameness >5%. These farmers practised routine foot trimming, footbathing and vaccination against footrot. Whilst 89% of farmers said they were satisfied with their management of FR over 34% were interested in changing management. Farmers identified veterinarians as the most influential source for new information. Farmers reported that ideally they would control FR by culling/isolating lame sheep, sourcing replacements from non-lame parents, trimming feet less, using antibacterial treatments less and using vaccination more. Footbathing was a commonly used management that was linked with dissatisfaction and that also was listed highly as an ideal management. Consequently, some of the ideal managements are in agreement with our understanding of disease control (culling and isolation, sourcing healthy replacements) but others are in contrast with our current knowledge of management and farmers self-reporting of satisfaction of management of footrot (less use of antibacterial treatment, more footbathing and vaccination). One explanation for this is the theory of cognitive dissonance where belief follows behaviour, i.e. farmers report that they believe an ideal which is what they are currently doing, even if the management is sub-optimal.

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 Pound630/100 ewes mated in the intervention group, including the cost of treatment of Pound150/100 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.

Vaccination against ovine footrot using a live bacterial vector to deliver basic protease antigen.

A strain of Corynebacterium pseudotuberculosis, designated Toxminus, that has been rationally attenuated by deletion of the phospholipase D gene, is being developed as a live vaccine vector for the delivery of veterinary vaccine antigens. In the present study a recombinant form of the basic protease gene of the ovine footrot causative bacterium, Dichelobacter nodosus, was introduced into the vector strain using the high copy number plasmid pEP2. This strain secreted the basic protease protein. Vaccination trials in sheep with the recombinant strain demonstrated that, although an IgG immune response was elicited, the animals were not protected from footrot following artificial challenge under pen conditions. Although the sheep were not protected there was evidence that the progression of the disease was slowed.