The importance of feet examination in sheep health management

The Use of Stromal Vascular Fraction in Long Bone Defect Healing in Sheep

The objectives of the present study were to evaluate (a) the feasibility of using stromal vascular fraction (SVF) and nanocrystalline hydroxyapatite (nHA) paste in combination for the treatment of segmental bone defect, (b) the quality of the callus produced, (c) the potential improvement of the autograft technique, and (d) the direct comparison of the biomaterial to the use of autogenous cancellous bone. Unilateral, segmental mid-diaphyseal bone defect was created on the right metatarsus of skeletally mature sheep animals (n = 24) under anesthesia (D0). Residual segments were stabilized by stainless-steel plates and appropriate screws. Defects were managed as follows: group A: use of nHA paste to filling, group B: use of autogenous bone graft mixed with nHA bone paste, placed in defect, group C: use of SVF mixed with nHA bone paste injected into defect, group D: use of bone graft and SVF with nHA paste before apposition in bone defect. SVF had been previously isolated from adipose tissue of the animals intra-operatively after digestion with collagenase solution and neutralization. Animals were evaluated clinically and by X-raying and ultrasonographic examination of the defect, at regular intervals, until D90. Ultrasonographic assessment performed along the length of the defect included calculation of the length of the bone defect and assessment of vascularization. SVF was successfully isolated from group C and D animals, with the average yield being 1.77 × 106 cells. The comparison of clinical scores (based on the 'Kaler scale') on each post-operative day indicated significant differences between the four groups on D1 to D30 (p < 0.01); the median clinical score within group A was 2.5 for D1-D30 and 1 for the entire period; respective scores for other groups were 1.5 (p = 0.07) and 0 (p = 0.033). Differences in radiographic assessment scores were significant for scores obtained on D60 (p = 0.049) and D90 (p = 0.006). There was a significant difference between the four groups in the length of the bone defect, as assessed ultrasonographically, for the entire length of the study; median values were 8, 8.5, 6, and 8 mm for groups A, B, C, and D, respectively (p = 0.008). There was a significance in the differences between median scores obtained during the histopathological examination: 2, 11, 13.5, and 12 for group A, B, C, and D (p = 0.022). There was an inverse correlation between the overall scores of histopathological evaluations and the length of the bone defect (observed on D90) (p < 0.0001) and a correlation between the overall scores and the radiographic assessment scores (obtained on D90) (p < 0.0001). This is the first study in which the efficacy of fresh autologous Stromal Vascular Fraction (SVF) from adipose tissue in enhancing bone healing in a long, weight-bearing, diaphyseal bone was evaluated. It is concluded that the lumbosacral region was an attractive site for harvesting adipose tissue, the use of SVF contributed to faster rehabilitation post-operatively, and SVF significantly enhanced bone formation; in general, the results indicated an osteogenic potential of SVF comparable to the gold standard autologous bone graft.

Reproducibility and Feasibility of Classification and National Guidelines for Histological Diagnosis of Canine Mammary Gland Tumours: A Multi-Institutional Ring Study

Histological diagnosis of Canine Mammary Tumours (CMTs) provides the basis for proper treatment and follow-up. Nowadays, its accuracy is poorly understood and variable interpretation of histological criteria leads to a lack of standardisation and impossibility to compare studies. This study aimed to quantify the reproducibility of histological diagnosis and grading in CMTs. A blinded ring test on 36 CMTs was performed by 15 veterinary pathologists with different levels of education, after discussion of critical points on the Davis-Thompson Foundation Classification and providing consensus guidelines. Kappa statistics were used to compare the interobserver variability. The overall concordance rate of diagnostic interpretations of WP on identification of hyperplasia-dysplasia/benign/malignant lesions showed a substantial agreement (average k ranging from 0.66 to 0.82, with a k-combined of 0.76). Instead, outcomes on ICD-O-3.2 morphological code /diagnosis of histotype had only a moderate agreement (average k ranging from 0.44 and 0.64, with a k-combined of 0.54). The results demonstrated that standardised classification and consensus guidelines can produce moderate to substantial agreement; however, further efforts are needed to increase this agreement in distinguishing benign versus malignant lesions and in histological grading.

Gamithromycin in sheep: Pharmacokinetics and clinical evaluation against ovine footrot

In the context of a development program to obtain the market authorization of injectable gamithromycin 15% w/v solution (Zactran®, Boehringer Ingelheim) for use in sheep against footrot, the pharmacokinetic profile of gamithromycin was established and the safety and efficacy of the treatment were confirmed in a multicenter field study in Europe. The basic pharmacokinetic parameters established in healthy young Merino sheep administered gamithromycin at 6 mg/kg body weight based on the analysis of plasma samples which were collected in intervals up to 12 days after subcutaneous injection were: area under the curve until last quantifiable concentration, 8.88 ± 2.33 μg*h/mL; maximum plasma concentration, 448 ± 180 ng/mL; terminal half-life, 42.5 ± 5.25 h. The safety and clinical efficacy against footrot of gamithromycin 15% w/v solution were evaluated in comparison to tilmicosin 30% w/v solution (Micotil®, Elanco) treatment in 364 sheep of various breeds, sex and age from commercial farms in the United Kingdom (2 sites), Germany (3 sites) and France (1 site). Animals were enrolled based on lesions characteristic of footrot and lameness associated with the presence of footrot-related bacterial pathogens and were randomly allocated and treated in a 1:1 ratio with a single subcutaneous dose of gamithromycin or tilmicosin at label dosage (6 or 10 mg/kg body weight, respectively). Lameness and footrot lesions were evaluated at five and 21 days after treatment; the injection site in all animals was examined the day after treatment and followed up daily in the animals with injection site reaction until complete injection site reaction resolution. Samples of 310 and 120 animals tested positive for Dichelobacter nodosus and Fusobacterium necrophorum, respectively, at inclusion, and data of 359 animals were included into the combined analyses (5 animals excluded for unintentional overdosing [1], lack of follow-up [1], concurrent antibiotic medication for non-footrot conditions [3]). Lameness scores at 21 days after treatment demonstrated a significantly (p = 0.0396) better success for the gamithromycin treatment compared to the tilmicosin treatment (97.8% vs. 93.3%). Post-dosing footrot lesion scores followed similar trends of rapid and marked decrease (improvement) for both treatments with similar (p = 0.127) treatment success for the gamithromycin and tilmicosin treatments (97.8% and 96.0%, respectively). Both treatments were safe; injection site reactions noted in 19 gamithromycin- and 25 tilmicosin-treated animals resolved within five days or six days of treatment, respectively. Gamithromycin 15% w/v solution administered once to sheep by subcutaneous injection at 6 mg/kg body weight demonstrated a pharmacokinetic profile similar to that reported previously in sheep and cattle and was confirmed to be a safe and efficacious treatment for naturally occurring ovine footrot in a multicenter clinical field study conducted in Europe.

Influence of Housing and Management on Claw Health in Swiss Dairy Goats

Simple Summary

Swiss dairy goats are commonly housed on deep littler, at least during the winter season. Due to the lack of horn wear, their claws often show overgrown wall horn. However, little is known about the impact of wall horn overgrowth on claw health and whether wall horn overgrowth impairs the goats’ locomotion behavior. Data was collected on 28 Swiss commercial dairy goat farms during autumn and spring. It was shown that severe wall horn overgrowth dominated during the indoor housing period and was associated with an increase in the proportion of claws with sole hemorrhages. Furthermore, wall horn overgrowth did not seem to have an effect on the goats’ locomotion behavior. The results of this study underline the importance of regular and careful claw trimming.

Abstract

Due to a rising demand for goat milk and goat milk products worldwide, it is likely that dairy goat production will be intensified in the future, with larger herds per farm. In Switzerland, as in many other countries with intensive farming systems, dairy goats are typically housed on deep litter, with little access to hard abrasive surfaces. Such housing conditions will result in wall horn overgrowth. The aim of this study was to gain profound knowledge on the occurrence of overgrown wall horn, its impact on claw health and locomotor behavior, and possible adverse effects on animal welfare. Additionally, housing and management factors that may contribute to non-physiological claw conditions were evaluated. To compare claw conditions after the summer grazing period and the winter indoor housing period, data were collected on 28 Swiss dairy goat farms in autumn and spring (621 goats in total). Claw lesions were recorded with the help of a “claw card” documenting each claw. Furthermore, pictures were taken of each claw to determine the severity of wall horn overgrowth. Locomotion behavior (activity, lying time and lying bouts) was recorded with three-dimensional accelerometers fixed to the goats’ hind legs. In autumn, 66.7% of the examined claws showed moderate overgrowth, 32.4% severe overgrowth and 0.9% no overgrowth. In spring, 47.4% of the examined claws were affected with moderate overgrowth, 52.6% with severe overgrowth and 0.0% with no overgrowth. Horn separation (48.1% of examined claws) and sole hemorrhages (16.0% of examined claws) were the most frequent lesions. In goats with severely overgrown claws, the risk of developing sole hemorrhages was doubled compared with moderate overgrowth. The occurrence rate of horn separation was lower if the trimmer had attended a special skills training course (p < 0.001). Furthermore, locomotor activity (p < 0.01) and the number of lying bouts per day (p < 0.01) were higher in spring than autumn. Neither the goats’ activity nor the number of lying bouts per day differed before and after claw trimming. Finally, season and trimming were not associated with the goats’ total lying time. A certain extent of wall horn overgrowth in dairy goat claws cannot be avoided under the housing conditions typical for Swiss farms. Severe wall horn overgrowth is associated with an increase in the proportion of claws with sole hemorrhages. Therefore, regular and careful functional claw trimming, taking the housing situation (deep bedding, access to pasture, grazing on alpine pasture) into account, should be promoted.

A Cross-Sectional Epizootiological Study and Risk Assessment of Foot-Related Lesions and Lameness in Intensive Dairy Sheep Farms

Simple Summary

Foot-related lameness is one of the most significant welfare issues in farm animals. Contrary to dairy cows and meat sheep breeds, epizootiological data on foot-lesions and associated lameness in dairy sheep are scarce. In this study, data were collected from 30 representative intensive dairy sheep farms. Multivariate statistical analysis was used to produce a typology of intensive farming systems which resulted in the assignment of farms in two distinct clusters. Six hundred adult ewes were randomly selected from six flocks (three flocks per cluster) and a cross-sectional study was implemented to investigate the epizootiology and potential risk factors of foot-related lameness, foot-lesions and diseases. Ovine interdigital dermatitis and infectious footrot were the most common infectious foot diseases, while white line disease and hoof wall cracks were the most prevalent non-infectious lesions. Infectious footrot was the main cause of lameness and increased with age, whereas body condition score was associated with increased prevalence of ovine interdigital dermatitis. Comparisons between the clusters regarding foot-related lameness, foot-diseases and lesions at the animal, the limb, and the hoof level are presented, and relevant literature, mechanisms, hypotheses, and challenges of the field are discussed.

Abstract

Foot-related lameness, foot-diseases and lesions are emerging issues in dairy sheep; however, relevant epizootiological studies are scarce, and risk factors have not been elucidated. The objectives of this cross-sectional study were (i) to address this dearth of knowledge by investigating the epizootiology of lameness-related foot-lesions and diseases, and (ii) to assess the impact of potential risk factors on foot health, in intensive dairy sheep farms. Thirty farms were assigned in two representative clusters using a multivariate statistical analysis. Three farms per cluster and 100 multiparous milking ewes per farm (total n = 600) were selected and enrolled in the study. Foot-related lameness, ovine interdigital dermatitis (OID), infectious footrot (IFR), white line disease, hoof wall cracks, as well as health and welfare traits were recorded. Overall prevalence of foot-related lameness was 9.0% and was primarily associated with IFR; however, additional infectious and non-infectious foot diseases and lesions also contributed. Among infectious foot diseases, OID was the most prevalent (21.3%) followed by IFR (8.0%); WLD and hoof wall cracks were the most prevalent non-infectious foot-lesions (37.7% and 15.3%, respectively). IFR and OID prevalence increased with age (p < 0.05) and BCS (p < 0.01), respectively, suggesting that host-related factors and husbandry practices are important determinants of its occurrence.

Predicting Lameness in Sheep Activity Using Tri-Axial Acceleration Signals

Simple Summary

Monitoring livestock farmed under extensive conditions is challenging and this is particularly difficult when observing animal behaviour at an individual level. Lameness is a disease symptom that has traditionally relied on visual inspection to detect those animals with an abnormal walking pattern. More recently, accelerometer sensors have been used in other livestock industries to detect lame animals. These devices are able to record changes in activity intensity, allowing us to differentiate between a grazing, walking, and resting animal. Using these on-animal sensors, grazing, standing, walking, and lame walking were accurately detected from an ear attached sensor. With further development, this classification algorithm could be linked with an automatic livestock monitoring system to provide real time information on individual health status, something that is practically not possible under current extensive livestock production systems.

Abstract

Lameness is a clinical symptom associated with a number of sheep diseases around the world, having adverse effects on weight gain, fertility, and lamb birth weight, and increasing the risk of secondary diseases. Current methods to identify lame animals rely on labour intensive visual inspection. The aim of this current study was to determine the ability of a collar, leg, and ear attached tri-axial accelerometer to discriminate between sound and lame gait movement in sheep. Data were separated into 10 s mutually exclusive behaviour epochs and subjected to Quadratic Discriminant Analysis (QDA). Initial analysis showed the high misclassification of lame grazing events with sound grazing and standing from all deployment modes. The final classification model, which included lame walking and all sound activity classes, yielded a prediction accuracy for lame locomotion of 82%, 35%, and 87% for the ear, collar, and leg deployments, respectively. Misclassification of sound walking with lame walking within the leg accelerometer dataset highlights the superiority of an ear mode of attachment for the classification of lame gait characteristics based on time series accelerometer data.

A financial cost-benefit analysis of eradicating virulent footrot

In 2008, virulent footrot was detected in sheep in south-west Norway. Footrot is caused by Dichelobacter nodosus, and the outbreak was linked to live sheep imported from Denmark in 2005. A large-scale program for eradicating the disease was implemented as a joint industry and governmental driven eradication project in the years 2008-2014, and continued with surveillance and control measures by the Norwegian Food Safety Authority from 2015. The cost of the eradication program including surveillance and control measures until 2032 was assumed to reach approximately €10.8 million (NOK 90 million). A financial cost-benefit analysis, comparing costs in the eradication program with costs in two simulated scenarios, was carried out. In the scenarios, designated ModerateSpread (baseline) and SlowSpread, it was assumed that the sheep farmers would undertake some voluntary measures on their own that would slow the spread of the disease. The program obtained a positive NPV after approximately 12 years. In a stochastic analysis, the probabilities of a positive NPV were estimated to 1.000 and to 0.648 after 15 years and to 0.378 and 0.016 after ten years, for the ModerateSpread and SlowSpread scenarios respectively. A rapid start-up of the program soon after the detection of the disease was considered crucial for the economic success as the disease would have become more widespread and probably raised the costs considerably at a later start-up.

Inter-observer agreement for clinical examinations of foot lesions of sheep

In sheep, the diagnosis of foot lesions is routinely based on physical examination of the hoof. Correct diagnosis is important for the effective treatment, prevention and control of both infectious and non-infectious causes of lameness. Therefore, the aim of this study was to evaluate the level of inter-observer agreement for clinical examination of ovine foot lesions. Eight observers of varying experience, training and occupation performed foot examinations on a total of 1158 sheep from 38 farms across North England and Wales. On each farm, a group of two to four observers independently examined a sample of 24 to 30 sheep to diagnose the presence or absence of specific foot lesions including white line lesions (WL), contagious ovine digital dermatitis (CODD), footrot (FR), inter-digital dermatitis (ID) and toe granuloma (TG). The inter-observer agreement of foot lesion assessments was examined using Fleiss kappa (κ), and Cohen's κ examined the paired agreement between the test standard observer (TSO) and each observer. Scoring differences with the TSO were examined as the percentage of scoring errors and assessed for evidence of systematic scoring bias. With the exception of WL (maximum error rate 33.3%), few scoring differences with the TSO occurred (maximum error rate 3.3%). This suggests that observers can achieve good levels of reliability when diagnosing most of the commonly observed foot conditions associated with lameness in sheep.

A systematic review of animal based indicators of sheep welfare on farm, at market and during transport, and qualitative appraisal of their validity and feasibility for use in UK abattoirs

In the UK, it has been suggested that abattoirs are ideal locations to assess the welfare of sheep as most are slaughtered at abattoirs either as finished lambs or cull ewes. Data from abattoirs could provide benchmarks for welfare indicators at a national level, as well as demonstrating how these change over time. Additionally, feedback could be provided to farmers and regulatory authorities to help improve welfare and identify high or low standards for quality assurance or risk-based inspections. A systematic review of the scientific literature was conducted, which identified 48 animal-based indicators of sheep welfare that were categorised by the Five Freedoms. Their validity as measures of welfare and feasibility for use in abattoirs were evaluated as potential measures of prior sheep welfare on the farm of origin, at market, or during transportation to the abattoir. A total of 19 indicators were considered valid, of which nine were considered theoretically feasible for assessing sheep welfare at abattoirs; these were body cleanliness, carcass bruising, diarrhoea, skin lesions, skin irritation, castration, ear notching, tail docking and animals recorded as 'obviously sick'. Further investigation of these indicators is required to test their reliability and repeatability in abattoirs. Novel welfare indicators are needed to assess short-term hunger and thirst, prior normal behaviour and long-term fear and distress.

Contagious ovine digital dermatitis: an emerging disease

The novel sheep disease, contagious ovine digital dermatitis (CODD) was first described in the UK in 1997. The disease is characterised by severe lameness associated with initial inflammation at the coronary band, followed by progressive separation of the hoof capsule from the underlying tissue. On microbiological examination, treponeme bacteria have been frequently isolated from cases of CODD, including treponemes phylogenetically identical to those associated with bovine digital dermatitis (BDD). Dichelobacter nodosus and Fusobacterium necrophorum have also been isolated from CODD lesions although their role in the pathogenesis remains uncertain. While epidemiological data indicate that the prevalence of CODD is increasing in the UK, the routes of transmission and associated risk factors have not been clearly elucidated. Evidenced-based treatment trials indicate that parenteral administration of long-acting amoxicillin is an efficacious treatment for CODD, while anecdotal evidence suggests other antibiotics, given locally and/or parenterally, may also be beneficial. Further microbiological and epidemiological research is urgently required to develop sustainable control strategies, including the development of vaccines and appropriate biosecurity and farm management protocols. In this review current knowledge of the clinical, aetiological, and epidemiological aspects of CODD is assessed as well as approaches to its control.

Scientific Opinion on the public health hazards to be covered by inspection of meat from sheep and goats

A risk ranking process identified Toxoplasma gondii and pathogenic verocytotoxin-producing Escherichia coli (VTEC) as the most relevant biological hazards for meat inspection of sheep and goats. As these are not detected by traditional meat inspection, a meat safety assurance system using risk-based interventions was proposed. Further studies are required on T. gondii and pathogenic VTEC. If new information confirms these hazards as a high risk to public health from meat from sheep or goats, setting targets at carcass level should be considered. Other elements of the system are risk-categorisation of flocks/herds based on improved Food Chain Information (FCI), classification of abattoirs according to their capability to reduce faecal contamination, and use of improved process hygiene criteria. It is proposed to omit palpation and incision from post-mortem inspection in animals subjected to routine slaughter. For chemical hazards, dioxins and dioxin-like polychlorinated biphenyls were ranked as being of high potential concern. Monitoring programmes for chemical hazards should be more flexible and based on the risk of occurrence, taking into account FCI, which should be expanded to reflect the extensive production systems used, and the ranking of chemical substances, which should be regularly updated and include new hazards. Control programmes across the food chain, national residue control plans, feed control and monitoring of environmental contaminants should be better integrated. Meat inspection is a valuable tool for surveillance and monitoring of animal health and welfare conditions. Omission of palpation and incision would reduce detection effectiveness for tuberculosis and fasciolosis at animal level. Surveillance of tuberculosis at the slaughterhouse in small ruminants should be improved and encouraged, as this is in practice the only surveillance system available. Extended use of FCI could compensate for some, but not all, the information on animal health and welfare lost if only visual post-mortem inspection is applied.

The radiographic anatomy of the normal ovine digit, the metacarpophalangeal and metatarsophalangeal joints

The aim of this project was to develop a detailed, accessible set of reference images of the normal radiographic anatomy of the ovine digit up to and including the metacarpo/metatatarsophalangeal joints. The lower front and hind limbs of 5 Lleyn ewes were radiographed using portable radiography equipment, a digital image processer and standard projections. Twenty images, illustrating the normal radiographic anatomy of the limb were selected, labelled and presented along with a detailed description and corresponding images of the bony skeleton. These images are aimed to be of assistance to veterinary surgeons, veterinary students and veterinary researchers by enabling understanding of the normal anatomy of the ovine lower limb, and allowing comparison with the abnormal.

Treatment and control of hoof disorders in sheep and goats

Lame sheep experience pain and should be treated as soon as reasonably practical. Treatment and control should be based on a firm diagnosis, and farmers should be encouraged to seek veterinary attention for animals that do not respond quickly to administered treatment. Overall flock lameness should be minimized through implementing appropriate control measures for the common types of foot lameness caused by infectious agents, including vaccination, antibiotic treatment, footbathing, biosecurity, and culling.