Mendelian randomization analysis of 34,497 German Holstein cows to infer causal associations between milk production and health traits.

BACKGROUND: Claw diseases and mastitis represent the most important health issues in dairy cattle with a frequently mentioned connection to milk production. Although many studies have aimed at investigating this connection in more detail by estimating genetic correlations, they do not provide information about causality. An alternative is to carry out Mendelian randomization (MR) studies using genetic variants to investigate the effect of an exposure on an outcome trait mediated by genetic variants. No study has yet investigated the causal association of milk yield (MY) with health traits in dairy cattle. Hence, we performed a MR analysis of MY and seven health traits using imputed whole-genome sequence data from 34,497 German Holstein cows. We applied a method that uses summary statistics and removes horizontal pleiotropic variants (having an effect on both traits), which improves the power and unbiasedness of MR studies. In addition, genetic correlations between MY and each health trait were estimated to compare them with the estimates of causal effects that we expected. RESULTS: All genetic correlations between MY and each health trait were negative, ranging from - 0.303 (mastitis) to - 0.019 (digital dermatitis), which indicates a reduced health status as MY increases. The only non-significant correlation was between MY and digital dermatitis. In addition, each causal association was negative, ranging from - 0.131 (mastitis) to - 0.034 (laminitis), but the number of significant associations was reduced to five nominal and two experiment-wide significant results. The latter were between MY and mastitis and between MY and digital phlegmon. Horizontal pleiotropic variants were identified for mastitis, digital dermatitis and digital phlegmon. They were located within or nearby variants that were previously reported to have a horizontal pleiotropic effect, e.g., on milk production and somatic cell count. CONCLUSIONS: Our results confirm the known negative genetic connection between health traits and MY in dairy cattle. In addition, they provide new information about causality, which for example points to the negative energy balance mediating the connection between these traits. This knowledge helps to better understand whether the negative genetic correlation is based on pleiotropy, linkage between causal variants for both trait complexes, or indeed on a causal association.

Digital dermatitis-associated Treponema species detection and quantification in migratory tundra caribou (Rangifer tarandus).

Treponema spp. are associated with infectious lameness in livestock and wild ruminants. While extensive research has been conducted on cattle, investigations in wild ruminants are scarce. Hoof disease is common in caribou populations (Rangifer tarandus), but investigations are limited due to the remoteness of the Arctic. Our study aimed to assess the presence of Treponema spp. associated with bovine digital dermatitis in caribou. DNA was extracted from coronary band tissues from forty-eight caribou without visible hoof lesions and analyzed using two PCR methods (qPCR and nPCR). Treponema spp. were detected in low copy numbers/mg of tissue (3.6 to 6.6 × 101). T. phagedenis was the most prevalent and abundant species in 58% of samples by qPCR, followed by T. medium (44%), and T. pedis (10%). The qPCR and nPCR agreement ranged between 65% and 75% (Cohen's kappa 0.22-0.51). Sanger sequencing of thirteen nPCR products confirmed that treponemes in caribou are remarkably similar to those found in domestic ruminants and wild elk. Our study highlights the colonization of treponemes in healthy hooves of a wild ruminant in the Arctic, where there is no presence of livestock, and expands knowledge on the host range and distribution of treponemes. These findings also emphasize the need for further research into the multifactorial nature of treponema-associated hoof diseases and the putative role of treponemes in infectious lameness affecting caribou.

Evaluation of selected risk factors for different stages of digital dermatitis in Dutch dairy cows.

Digital dermatitis (DD) is a painful infectious disease in dairy cattle that causes ulcerative lesions of the skin just above the coronary band, mainly of the hind legs. Estimates for DD prevalence at cow level in the Netherlands range from 20% to 25%. In this study, risk factors for the various stages of DD were identified and quantified. The hind legs of 6766 cows on 88 farms were scored by trained interns, using the M-scoring system (M0-M4.1). Farms in this study were a convenience sample, based on the prevalence of DD as recorded at the latest herd trim, geographical location and willingness of the farmers to participate. A survey with questions about cow environment and herd management was conducted by the intern at the day of scoring. The data were collected between August 2017 and January 2018. DD was found on 38.6% of the scored legs; 49.8% of the cows had DD on at least one leg and M4 was the most frequent stage (20.9%). Not removing manure on a regular basis resulted in lower odds for M2, M4 and M4.1 compared to cleaning by automatic scrapers ten times a day or more (odds ratio [OR]= 0.16, 0.49 and 0.18, respectively). The odds for M2 and M4 lesions were higher in cows aged 3-5 years than in first-calved cows (OR> 1.5 and > 1.7, respectively). Rubber flooring in the passageways resulted in lower odds for both M1 and M2 (OR, 0.06 and 0.32, respectively). Prophylactic use of footbaths treatment with an alternative active compound resulted in significant higher odds for M4 lesions than formalin and a combination of formalin and copper sulphate (OR= 1.69 and 2.04 respectively). The odds for an M4.1 lesion were lower in cows from smaller herds (n = 50-100) compared to large herds (n >100; OR= 0.67).

Evaluation of potassium monopersulfate footbath solution for controlling digital dermatitis in lactating dairy cattle. A randomized clinical trial.

Our objective was to assess potassium monopersulfate as a disinfectant used in footbath to control digital dermatitis (DD) in dairy cows. We hypothesized that a potassium monopersulfate solution would control DD. A 180-day randomized negative controlled trial was conducted in a 265-Holstein free-stall facility. Throughout the trial, foot bathing was performed bi-weekly using a split (left vs. right feet) footbath: one tub filled with 1% potassium monopersulfate (treatment), the other with tap water (control). Digital dermatitis lesions were scored during trimming chute examinations of the unwashed hind heels every 90 days using the modified M-scoring system. Digital dermatitis lesions were re-categorized into four variables: 1) inactive; 2) active; 3) any; 4) inactive or absence of DD lesions. Three longitudinal outcomes were characterized: risks of 1) developing a DD lesion; 2) reactivating an inactive DD lesion; 3) development of an inactive or the absence of the DD lesion. A generalized linear model was used to compare the variables and longitudinal outcomes between treated and control groups. Prevalence of active DD lesions increased from 12.5% to 39.9% between days 0 and 90. This significant increase in prevalence justified the discontinuation of the study on day 90 for ethical reasons. There was no statistical difference between treated and control groups for the first outcome (RR: 1.0; 95% CI: 0.62, 1.7), the second outcome (RR: 1.0; 95% CI: 0.62,-1.7); or the third outcome (RR: 0.88; 95% CI: 0.37, 2.1). A 1% potassium monopersulfate footbath solution appears ineffective to control DD in this study.

Proinflammatory CD14highCD16low monocytes/macrophages prevail in Treponema phagedenis-associated bovine digital dermatitis.

Digital dermatitis (DD) is a skin disease in cattle characterized by painful inflammatory ulcerative lesions in the feet, mostly associated with local colonization by Treponema spp., including Treponema phagedenis. The reason why most DD lesions remain actively inflamed and progress to chronic conditions despite antibiotic treatment remains unknown. Herein, we show an abundant infiltration of proinflammatory (CD14highCD16low) monocytes/macrophages in active DD lesions, a skin response that was not mitigated by topical treatment with oxytetracycline. The associated bacterium, T. phagedenis, isolated from DD lesions in cattle, when injected subcutaneously into mice, induced abscesses with a local recruitment of Ly6G+ neutrophils and proinflammatory (Ly6ChighCCR2+) monocytes/macrophages, which appeared at infection onset (4 days post challenge) and persisted for at least 7 days post challenge. When exploring the ability of macrophages to regulate inflammation, we showed that bovine blood-derived macrophages challenged with live T. phagedenis or its structural components secreted IL-1ß via a mechanism dependent on the NLRP3 inflammasome. This study shows that proinflammatory characteristics of monocytes/macrophages and neutrophils dominate active non-healing ulcerative lesions in active DD, thus likely impeding wound healing after antibiotic treatment.

Quantifying and mapping digital dermatitis-associated bacteria in lesion and nonlesion body sites and dairy farm environment.

The source of infection of digital dermatitis (DD), an infectious lameness condition, is still uncertain. In this cross-sectional study, we aimed to identify potential reservoirs of DD bacteria in dairy cattle body sites with different stages of the disease and farm environments. We collected skin swabs from 85 dairy cows from 5 herds, 3 with and 2 without DD, from foot, hock, and udder cleft skin (with lesions or not), saliva, urine, and feces. We also obtained environmental samples. Real-time quantitative PCR targeted Treponema phagedenis, Treponema medium, Treponema pedis, Porphyromonas levii, Bacteroides pyogenes, Fusobacterium necrophorum, and Fusobacterium mortiferum. Digital dermatitis-associated Treponema spp. were exclusively detected in DD-affected herds in DD-foot and other skin lesions, healthy skin, saliva, and environmental samples. In contrast, the non-Treponema spp. were found in samples from both DD-negative and affected herds. As expected, DD lesions had higher bacterial loads than healthy skin. Interestingly, similar counts were observed in udder cleft lesions, indicating a potential opportunistic behavior on compromised skin. None of the targeted species were detected in fecal samples, but P. levii, B. pyogenes, and F. necrophorum were detected in urine. All 7 species were detected in saliva, although in low quantities. No associations were observed between the presence of each bacterial species in DD lesions and urine; however, there was an association between the presence of DD-Treponema spp. in lesions and saliva, hock, and udder skin. Feces and urine do not seem to be a DD bacteria primary source, but saliva and other skin lesions may play a role. Longitudinal studies would improve our understanding of DD-associated bacteria's transient or persistent presence in these sites. Investigating the sources of DD-associated bacteria will guide future interventions to minimize bacterial shedding and transmission, ultimately more effectively reducing bacterial load, transmission, and sources of infection in dairy herds.

Routine hoof-trimming data provides insight into the occurrence of claw lesions in Holstein herds in the central region of South Africa.

Claw lesions in dairy cows contribute significantly to lameness, causing distress and discomfort for affected cows and raising welfare concerns. Despite increased awareness, lameness incidence continues to rise. Defining and recording claw traits are particularly problematic. In South Africa (SA), claw data is limited to paper-based records kept by private hoof trimmers. This research analysed claw-trimming data from five dairy farms over 6 years to examine the occurrence and recording of claw lesions in SA Holstein cattle. Lesion identification followed the Claw Lesion Identification in Dairy Cattle brochure. Among the recorded lesions, digital dermatitis (DD) had the highest prevalence (64.02%), followed by sole ulcers (SU; 8.59%), white line disease (WLD; 6.27%), and sole haemorrhage (SH; 4.28%), and most lesions occurred in the rear feet. Chi-square tests and correspondence analysis (CA) were employed to explore the relationships between lesions, feet, and housing. Results indicated that the prevalence of SU and SH showed high similarity for foot and lesion association, and that these were more highly associated with the rear feet. Additionally, the prevalence of DD and interdigital phlegmon were strongly associated, and closely associated with SU, and all these lesions were associated with both dirt lot and free-stall housing systems. CA further confirmed a close association between WLD and SH, and the prevalence of these lesions in the combination housing system. Results of this study highlight the complexity of lesion data and that specific associations between lesions could lead to simplifying the recording thereof. Consolidating the most informative claw lesions into categories will aid in the practical prevention, management, and treatment of lameness on-farm.

[Risk factors for chronic perforating skin lesions in the area of the digits in cattle on Swiss alpine pastures]. / Risikofaktoren für chronisch perforierende Hautläsionen im Zehenbereich beim Rind auf Schweizer Alpen.

INTRODUCTION: Diseases of the digits often occur in cattle on larger cattle mountain pastures. In the late spring 2020, at the time of the ascent of 1554 cattle to 11 high altitude alpine pastures in the Lower Engadine region, lesions in the area of the digits were clinically assessed and documented. 254 cattle were of non-cantonal and 1300 of local origin (Lower Engadine; postal code CH-75XX). Skin lesions in the area of the digits, identified as digital dermatitis (DD; Mortellaro's disease), were further classified according to the DD scoring system. Nonspecific skin lesions with clinical evidence of granulation tissue formation were termed chronic penetrating skin lesions (CPSL). At the end of the alpine pasturing season, in the early fall (descent of cattle from the alpine pastures), the procedure was repeated, and biopsies were taken from randomly selected cattle with CPSL. Digital dermatitis lesions were found in 34 of 1551 cattle at ascent, but no case of CPSL was found at that time. At descent, 19 of 1529 cattle had DD lesions and 88 cattle had CPSL. The clinical appearance of the CPSL was consistent with chronic skin lesions caused by penetrating skin lacerations. Histologically, the majority of the CPSL were classified as chronic hyperplastic dermatitis with granulation tissue formation. In all CPSL biopsies examined by PCR, Fusobacterium necrophorum and Porphyromonas levii, but neither Dichelobacter nodosus nor the tested Treponema species were detected. Fluorescence in situ hybridization revealed a negative result for Treponema species in all biopsies. In the regression analysis, cattle in the age group of 365 to 730 days had an increased risk for the presence of CPSL compared to the age group of 160 to 365 days (odds ratio (OR) = 4,95; confidence interval (CI) = 1,97-12,43). Holstein cattle had an increased risk of developing CPSL compared to Brown cattle (OR = 2,92; CI = 1,46-5,86) and cattle of non-cantonal origin showed a massively higher risk compared to local cattle (OR = 10,59; CI = 5,79 - 19,37). The statistically significant associations found in the present study can be taken into account in the selection of animals for summer pasturing on high altitudes in the future in order to reduce the prevalence of CPSL and consequently reduce the antimicrobial use. Spread of DD during the alpine pasturing season within the cattle groups examined was not found.

INTRODUCTION: Des atteintes aux onglons sont souvent observées sur les grands alpages de bovins. Des altérations au niveau des onglons ont été examinées cliniquement et répertoriées chez 1554 bovins lors de leur arrivée sur 11 alpages en Basse-Engadine, en provenance d'un autre canton (n = 254) ou de la localité à laquelle l'alpage appartenait (n = 1300, numéro postal 75XX), au moment de la montée à l'alpage en 2020. Les altérations cutanées diagnostiquées comme dermatite digitale (DD; maladie de Mortellaro) ont de plus été classifiées selon les scores en usage pour la DD. Les lésions cutanées non-spécifiques présentant une formation de tissu de granulation ont été enregistrées comme lésions cutanées perforantes chroniques (LCPC). La procédure a été répétée lors de la désalpe et une biopsie a été prise de chez des animaux présentant des LCPC choisis au hasard. Les caractéristiques de la topographie de l'alpage et celles du sol, ainsi que la densité d'occupation ont été enregistrées pour chaque alpage. Des lésions de DD ont été constatées chez 34 des 1551 bovins lors de la montée à l'alpage, mais aucun cas de LCPC n'a été observé. Lors de la désalpe, 19 des 1551 bovins présentaient des lésions de DD et 88 une LCPC. L'apparence des LCPC correspondait à des lésions cutanées chroniques après une blessure perforante de la peau. À l'histologie, il s'agissait la plupart du temps d'une dermatite chronique hyperplastique avec formation de tissu de granulation. Fusobacterium necrophorum et Porphyromonas levii ont été mis en évidence dans toutes les biopsies de LCPC soumises à une analyse par PCR, mais ni Dichelobacter nodosus ni les Treponema spp. recherchées n'ont été mis en évidence. L'hybridation in-situ en fluorescence était négative pour les tréponèmes dans toutes les biopsies. Selon les résultats d'une analyse de régression, les génisses âgées de 366 à 730 jours avaient un risque augmenté (Odds Ratio (OR) = 4,95; intervalle de confiance (IC) = 1,97 ­ 12,43) de présenter une LCPC en comparaison avec le groupe d'âge de 161 à 365 jours. Les bovins de race Holstein avaient un risque augmenté de présenter une LCPC en comparaison avec ceux de race grise (OR = 2,92; IC = 1,46 ­ 5,86), et les animaux en provenance d'autres cantons présentaient un risque massivement plus élevé que le cheptel local (OR = 10,59; IC = 5,79 ­ 19,37). Aucune différence significative n'a été observée dans la topographie ou dans la densité d'occupation entre les alpages avec et sans cas de LCPC. Les associations statistiquement significatives constatées dans cette étude peuvent être prises en compte à l'avenir lors de la sélection d'animaux pour l'alpage, dans le but de réduire la prévalence de LCPC, de diminuer la quantité d'antibiotiques administrés et d'améliorer le bien-être animal. Une propagation de la DD pendant la saison d'alpage n'a pas été constatée dans les groupes de bovins inclus dans l'étude.

Efficacy of quaternary ammonium salt-based disinfectant or chelated copper-zinc footbath solution in the treatment of digital dermatitis on one research dairy farm in Taiwan.

BACKGROUND: Footbaths can be used to manage digital dermatitis (DD), a common cause of lameness in dairy cattle. Copper sulfate and chelated copper-zinc (CZS) solutions in footbaths are potentially harmful to the environment. HYPOTHESIS/OBJECTIVES: To determine if a quaternary ammonium salt-based disinfectant (QASD) footbath is as effective as a chelated CZS solution in controlling DD in dairy cows. ANIMALS: Fifty-one lactating Holstein cows were randomly assigned to one of two treatment groups, with DD status based on the M-stage scoring system and locomotion score balanced between treatment groups. MATERIALS AND METHODS: The groups were treated with a 1% QASD or a 2.5% chelated CZS. Footbaths were performed once per week for 15 weeks. Logistic regression was used to analyse clinical improvement. All cows received appropriate medical treatment for DD and other hoof diseases. RESULTS: Clinical improvement rates were 67% in the QASD group and 38% in the CZS group (p = 0.03). Logistic regression analysis showed that the odds (95% confidence interval) for clinical improvement rate in the CZS group were 0.30 (0.095-0.948) times that of the QASD group (p = 0.04). The M0 score in the QASD and CZS groups increased significantly (p < 0.05) at the end of the 15 week study period. In the QASD group, the proportion of M2, M3 and M4 scores were significantly decreased (p < 0.05). CONCLUSION AND CLINICAL RELEVANCE: Over a 15 week period, QASD for footbathing was associated with a lower prevalence of active DD lesions than when using CZS.

Transmission and lesion progression of treponeme-associated hoof disease in captive elk (Cervus canadensis).

Treponeme-associated hoof disease (TAHD) is a debilitating disease of free-ranging elk (Cervus canadensis) in the northwestern U.S. While treponemes are associated with lesions, the etiology and transmissibility between elk are unknown. Our objective was to determine whether the disease can be environmentally transmitted to captive elk. Four individually housed treatment elk and 2 control elk were challenged with soil mixed with inoculum prepared from free-ranging elk hooves from TAHD-positive elk or autoclaved hooves from normal elk, respectively. The inoculum for each group was applied to the interdigital space and added to pre-existing soil in each pen. Eight challenges were conducted at 1-4-week intervals and lesion development was assessed during a 138-day challenge period that was followed by a 170-day monitoring period to document lesion progression. All treatment elk, but no control elk, developed gross and histologic lesions consistent with TAHD. Treponema phylotypes similar to those in bovine digital dermatitis in cattle were detected using 16S rRNA gene amplicon sequencing from lesions in all treatment elk, but no control elk, during the challenge period. Lesions progressed from ulcerations in the interdigital space to extensive ulceration and underrunning of the hoof capsule by 35 and 173 days following the initial inoculation, respectively. Lameness in treatment elk was correlated with lesion development (R = 0.702, p≤0.001), and activity of infected elk was reduced during the challenge (p≤0.001) and monitoring periods (p = 0.004). Body condition was significantly lower in treatment than control elk 168 days following the initial inoculation (p = 0.05) and at each individual elk's study endpoint (p = 0.006). Three of 4 treatment elk were euthanized when they reached humane endpoints, and one elk recovered. These results provide direct evidence that TAHD is a transmissible infectious disease in elk. As such, actions that reduce transmission risk can support disease management and prevention.

Evidence of novel Treponema phylotypes implicated in contagious ovine digital dermatitis and association of treponemes with major lameness causing foot pathogens.

In this study 269 swabs collected from 254 ovine foot lesions and 15 apparently healthy ovine feet were screened by PCR for the presence of major lameness causing foot pathogens viz. Treponema species, D. nodosus, F. necrophorum and T. pyogenes with the presumption that ovine foot lesion positive for Treponema species alone or in association with other three pathogens were categorized as contagious ovine digital dermatitis (CODD). While samples positive for D. nodosus alone or its combination with F. necrophorum and T. pyogenes were considered as footrot (FR) and samples in which F. necrophorum or T. pyogenes was found either alone or in combination were considered as interdigital dermatitis (ID). The overall occurrence of Treponema sp. in ovine foot lesions was 48.0%, and ranged from 33 to 58%. In Treponema positive samples D. nodosus, F. necrophorum and T. pyogenes were present in 34 (27.4%), 66 (54.4%) and 84 (68.5%) in contrast to Treponema negative samples in which these were present in 15 (11.1%), 20 (14.12%) and 17 (12.6%) samples, respectively. The data signifies that Treponema sp. are significantly associated with these foot pathogens and their different combinations with Treponema sp. influence the severity of CODD lesion. The identification of Treponema phylotypes was done by sequencing the 16S rRNA gene fragment of ten representative samples. Out of ten sequences, four (Trep-2, Trep-4, Trep-7 and Trep-10) were identical to Treponema sp. phylotype 1 (PT1) that belongs to phylogroup T. refringens-like, one sequence (Trep-1) was genetically close (90% sequence homology) to Treponema brennaborense while five sequences (Trep-3, Trep-5, Trep-6, Trep-8 and Trep-9) matched with uncultured bacterium clones of treponemes forming separate monophyletic group in phylogenetic tree and could represent new digital dermatitis phylogroup presently containing five ovine specific phylotypes. This is the first report on the presence of Treponema phylotypes other than three digital dermatitis (DD) Treponema phylogroups viz. T. phagedenis-like, T. medium/T. vincentii-like, and T. pedis-like that are frequently detected in CODD lesions. Metagenomic analysis of two representative samples revealed the abundance of genus Treponema in CODD lesion while this genus was absent in swab collected from clinically healthy foot suggesting that it might play primary role in producing CODD. These findings may further aid in understanding the etiopathogenesis of CODD and could help to develop appropriate treatment and mitigation strategies to combat the disease.

Survival of bovine digital dermatitis treponemes in conditions relevant to the host and farm environment.

OBJECTIVES: Bovine digital dermatitis (BDD), a painful infectious foot disease in dairy cattle, endemic in many countries worldwide, causes substantial economic and welfare impacts. Treponema spp. are considered key to BDD pathogenesis. To aid infection reservoir identification and control measure development, survival of BDD treponemes was investigated in different temperatures (4, 12, 20, 37, 45 and 60 °C), pH values (5-9.0), dairy cattle faeces and bedding types: straw shavings, sand, sand containing 5% lime (w/w) and recycled manure solids (RMS). METHODS: A turbidity microplate methodology was adapted to measure pH impact on growth. Survival of BDD treponemes for the different conditions were assessed by sub-cultures of microcosms over different time points. RESULTS: BDD treponemes remained viable between 4 and 37 °C and pH 5.5 and 9.0 under anaerobic conditions. In sterile faecal microcosms, incubated aerobically at 12 °C, BDD treponemes remained viable for a median of 1 day (15 min - 6 day range). Variation in duration of survival and ability to grow was observed between phylogroups and strains. In aerobic microcosms, T. phagedenis T320A remained viable for the full 7 days in sand, 6 days in sawdust, 5 days in RMS, but was not viable after 15 min in straw or sand containing 5% (w/w) lime. CONCLUSIONS: Treponeme survival conditions identified here should enhance future BDD infection reservoir surveys and enable control measures. Of note, straw or sand containing 5% (w/w) lime should be assessed in BDD field trials. Finally, these data indicate BDD treponemes exhibit characteristics of facultative anaerobes.

Development of a multiplex quantitative PCR assay for simultaneous detection of Treponema phagedenis, Treponema pedis, Treponema medium, and 'Treponema vincentii' and evaluation on bovine digital dermatitis biopsies.

Bovine digital dermatitis (BDD) is a contagious foot disease with worldwide occurrence in dairy cattle. The disease causes lameness and reduced animal welfare as well as economic losses for the farmer. The aetiology is not fully established but associations have been made with Treponema spp. Today, BDD diagnosis is mainly based on visual inspection of cattle feet, therefore this study aimed to develop a multiplex quantitative PCR (qPCR) assay targeting Treponema phagedenis, Treponema pedis, Treponema medium, and 'Treponema vincentii' to aid in diagnosis. The assay was tested for specificity on 53 bacterial strains and in silico on 168 Treponema spp. genomes, representative of at least 24 species. In addition, 37 BDD biopsies were analysed and the results compared to another qPCR assay published during the study period, which we modified by combining into a multiplex qPCR. The qPCR developed herein had a detection limit of 10 copies of each target species per PCR reaction. Both qPCR assays showed 100% specificity when tested on bacterial strains, but the qPCR developed in this study detected 3.4% more T. phagedenis-positive biopsies of lesion category M1-M4.1 than the modified assay. To conclude, the developed qPCR assay detecting T. phagedenis, T. pedis, T. medium, and 'T. vincentii' has high analytical sensitivity and specificity and provides a useful complementary tool for diagnosis and epidemiological studies of BDD. The assay could possibly also be used for contagious ovine digital dermatitis (CODD) as similar bacteriological profiles have been suggested for BDD and CODD, especially regarding certain Treponema spp.

Comparison of clinical cure rates from footrot and contagious ovine digital dermatitis using zinc sulphate foot bathing and topical oxytetracycline: A randomised trial.

BACKGROUND: This study reports the clinical cure rates of topical oxytetracycline and 10% zinc sulphate foot bathing for treatment of interdigital dermatitis (ID), footrot (FR) and contagious ovine digital dermatitis (CODD) in lambs. METHODS: The study was a randomised controlled trial of 75 lambs. Group A (n = 38) was foot bathed daily for 5 days in 10% zinc sulphate for 15 minutes and group B was treated with daily topical oxytetracycline for 5 days. On days 0, 7, 14, 28 and 42, lambs were scored for locomotion and foot lesions were recorded. RESULTS: The initial cure rates for ID were 96.20% and 97.00%; for FR, 100% and 95%; and for CODD, 90.09% and 83.33% for zinc sulphate and oxytetracycline, respectively. By day 42, these had changed to 53.16% and 61% for ID; 47.82% and 70% for FR; and 100% and 83.33% for CODD. There were no significant differences in cure rates between the treatments for most time points. LIMITATIONS: The sample size was small, and further studies in larger cohorts and different classes of sheep are required before the findings can be translated into recommendations for clinical practice. CONCLUSION: Both treatments achieved cure rates that are comparable to reported cure rates using systemic antibiotics and could be an effective alternative.

A cross-sectional study of the prevalence of lameness and digital dermatitis in dairy cattle herds in Egypt.

BACKGROUND: Lameness is a significant problem for the dairy industry worldwide. No previous studies have evaluated the prevalence of lameness or digital dermatitis (DD) in dairy cattle herds in Egypt. A total of 16,098 dairy cows from 55 dairy herds in 11 Egyptian governorates underwent visual locomotion scoring using a 4-point scoring system. Cows that had a lameness score ≥ 2 were considered clinically lame. Following manure removal with water and using a flashlight, the cows' hind feet were examined in the milking parlour to identify DD lesions and classify with M-score. Furthermore, each cow was assigned a hock score (a 3-point scale) and a hygiene score (a 4-point scale). The cow-, within-and between-herd prevalence of lameness and DD and associated 95% confidence intervals (CI) were calculated. The prevalence of hock lesions and poor cow hygiene was also calculated. RESULTS: Of the examined cows, 6,883 were found to be clinically lame (42.8%, 95% CI = 42.0-43.5%). The average within-herd prevalence of lameness was 43.1% (95% CI = 35.9-50.3%). None of the dairy herds recruited into the study were found to be free from clinical lameness. The average within-herd prevalence of DD was 6.4% (95% CI = 4.9-8.0%). The herd-level prevalence of DD was 92.7% (95% CI = 85.9-99.6%). Active DD lesions (M1, M2, M4.1) were identified in 464 cows (2.9%) while inactive lesions (M3, M4) were identified in 559 cows (3.5%). The within-herd prevalence of hock lesions (score 2 or 3) was 12.6% (95% CI = 4.03-21.1%) while a severe hock lesion had within-herd prevalence of 0.31% (95% CI = 0.12-0.51%). Cow-level prevalence of hock lesions was 6.2% (n = 847, 95% CI = 5.8-6.2%). The majority of examined cows had a hygiene score of 4 (n = 10,814, prevalence = 70.3%, 95% CI = 69.5-71%). CONCLUSIONS: The prevalence of lameness was higher than prevalence estimates reported for other countries which could be due to differing management and/or environmental factors. DD was identified at lower prevalence in most herds but with high herd-level prevalence. Poor cow hygiene was notable in most herds. Measures to reduce the prevalence of lameness and to improve cow hygiene in dairy cattle herds in Egypt are therefore needed.

[Implementation of biosecurity measures by hoof trimmers in Switzerland]. / Umsetzung von Biosicherheitsmassnahmen durch Klauenpfleger in der Schweiz.

INTRODUCTION: Biosecurity in livestock farming includes all measures preventing pathogen introduction onto a farm (external biosecurity) and pathogen transmission on the farm itself (internal biosecurity). An important risk factor for the dissemination of infectious diseases are specialised external persons working on numerous farms, such as professional hoof trimmers in Switzerland. In the present study, 49 hoof trimmers, participating in the Swiss claw health programme and working as professionals, were questioned regarding their biosecurity measures and observed by two veterinarians during hoof trimming in order to assess the implementation of biosecurity measures by hoof trimmers. Data were processed using a scoring system, in which points were allocated to the different working methods taking into account their assumed transmission potential for infectious diseases such as digital dermatitis (DD) and Salmonellosis. The working method, which complied with the ideal biosecurity measure, was always given a whole point, whereas less optimal working methods were only given an intermediate value or no point. The scoring system helped identify precisely the strengths and weaknesses of the hoof trimmers in terms of biosecurity. The level of implementation of biosecurity measures by hoof trimmers was overall quite low (53 %=average of the overall biosecurity scores of the 49 hoof trimmers). Hoof trimmers which attended specialised training courses tended to have a higher level of implementation of biosecurity measures. The answers given by the hoof trimmers and the observations made by the veterinarians were compared, whereby it was found that hoof trimmers generally evaluated themselves better in regard to biosecurity than veterinarians assessed them. In summary and based on the results of this study, the dissemination of pathogens, such as DD associated treponemes and salmonella is possible during hoof trimming performed by external persons working on numerous farms. Thus, future training and continuing education courses should place emphasis on biosecurity.

INTRODUCTION: Le concept de biosécurité englobe, en lien avec la production animale, toutes les mesures empêchant l'introduction de germes dans une exploitation (biosécurité externe) et la propagation de germes à l'intérieur de l'exploitation (biosécurité interne). Un facteur de risque important pour la propagation de maladies infectieuses est le personnel spécialisé externe travaillant sur plusieurs exploitations, dont font partie les pareurs d'onglons professionnels intervenant sur les exploitations bovines suisses. Dans la présente étude, afin de donner un aperçu de la situation actuelle concernant la mise en oeuvre de mesures de biosécurité par les pareurs d'onglons, 49 pareurs d'onglons participant au programme suisse de santé des onglons, ont été questionnés à ce sujet et observés lors du parage des onglons par des vétérinaires. Le traitement des données a été effectué à l'aide d'un système de notation, attribuant des points aux différentes pratiques de travail selon leur potentiel supposé de transmission des maladies infectieuses que sont la Dermatite digitale (DD) et la Salmonellose. La pratique de travail, qui correspondait à la mesure de biosécurité idéale, obtenait toujours un point entier, alors que les pratiques de travail moins optimales ne recevaient qu'une valeur intermédiaire ou aucun point. Le système de notation a permis de désigner précisément les forces et les faiblesses des pareurs d'onglons en terme de biosécurité. Le niveau de mise en œuvre de mesures de biosécurité par les pareurs d'onglons est de manière générale relativement faible (53 % = moyenne du score de biosécurité générale des 49 pareurs). Les pareurs d'onglons ayant suivi plus fréquemment des formations spécifiques présentaient tendanciellement un niveau de mise en oeuvre de mesures de biosécurité plus élevé. De plus, les réponses des pareurs d'onglons et les observations des vétérinaires ont été comparées. Il a été constaté, que les pareurs d'onglons s'évaluaient généralement meilleurs en matière de biosécurité que les vétérinaires ne les jugeaient. En résumé et en tenant compte des résultats de cette étude, la propagation de germes pathogènes par les pareurs d'onglons dans le cadre de leur activité professionnelle, tels que les tréponèmes associés à la DD et les salmonelles, est possible. Par conséquent, la biosécurité devrait être thématisée en priorité lors des formations et formations continues futures.

[Risk factors for infectious foot -disorders on two Swiss cattle -mountain pastures]. / Risikofaktoren für infektiöse Zehen­erkrankungen auf zwei Schweizer ­Rinderalpen.

INTRODUCTION: In the present study, risk groups for infectious foot disorders were identified on two large Swiss cattle mountain pastures by analyzing animal and treatment data of a total of 3256 animals of the bovine species. Both mountain pastures were part of the Federal Office for Agriculture (FOAG) consultancy project «Healthy animals, attractive herdsmen positions and less medication on large cattle mountain pastures¼. The project was launched in 2020 following the increased incidence of lameness on these mountain pastures. Bacteriological and histological analyses were to provide information as to whether the most common foot disorder was interdigital phlegmon (IP) or whether digital dermatitis also occurred. Further, the temporal distribution of cases over the mountain pasture season and the influence of mountain pasture and year were investigated and interpreted for the project years 2020 to 2022, and treatment incidences were compared between years. Multiple treatment cycles in the same individual were classified into persistent infections and new infections. Nineteen of 394 first-treated cattle were clinically examined, 12 of them were additionally sampled for bacteriological and histological analyses. All cases examined showed, both clinically and following laboratory analyses, typical characteristics for IP. In contrast, there was no specific evidence for the presence of digital dermatitis. No persistent infections occurred during treatment with benzylpenicillin. Multivariate logistic regression analyses identified > 365-730-day-old cattle (odds ratio OR 8,29), as well as inseminated (OR 5,30) and non-inseminated (OR 7,85) heifers as risk groups for the disease studied (p < 0,05). Association with the oestrus activity of non-inseminated heifers and a generally higher locomotor activity in heifers compared to cows - with a correspondingly increased risk of injury - is conceivable. Meat breeds had a reduced risk compared to dairy breeds (OR 0,29). Breed differences in behavior and/or the effectiveness of the local immune response might have an impact. Knowing about these risk groups can be put to use in the future when selecting animals to be taken to the mountain pastures and/or when planning pasture management in order to reduce the prevalence of infectious foot disorders and thereby the use of antibiotics.

INTRODUCTION: Dans la présente étude, nous avons identifié, grâce à l'analyse des données concernant les animaux et les traitements d'un total de 3256 animaux de l'espèce bovine, des groupes à risque pour les maladies infectieuses des onglons sur deux grands alpages bovins en Suisse. Les deux alpages faisaient partie du BLW-projet de conseil «Animaux sains, postes de bergers attractifs et moins de médicaments sur les grands alpages bovins¼. Le projet a débuté en 2020 suite à l'accumulation de problèmes de boiteries sur ces alpages. Des analyses bactériologiques et histologiques devaient fournir des indications afin de savoir si la maladie des onglons majoritaire était le phlegmon interdigité (PI) ou si la dermatite digitale était également présente. La répartition temporelle des cas de maladies durant la saison d'estivage et l'influence de l'alpage et de l'année pour les années de projet 2020 à 2022 ont été évaluées et interprétées, et les incidences des traitements comparées entre les années. Les cycles de traitement multiples chez le même individu ont été répartis en deux groupes: les infections persistantes et les nouvelles infections. Dix-neuf des 394 bovins primo-traités ont été évalués cliniquement. Douze de ces 19 animaux ont également été soumis à un échantillonnage bactériologique et histologique. Tous les cas étudiés présentaient, aussi bien cliniquement que suite à l'analyse technique en laboratoire, les caractéristiques typiques d'un PI. Par contre, il n'y a pas eu d'indication quant à la présence de dermatite digitale. Aucune infection persistante n'a été constatée après traitement avec de la Benzylpénicilline. Les bovins âgés > 365­730 jours (OR 8.29), ainsi que les génisses inséminées (odds ratio OR 5.30) et non inséminées (OR 7.85) ont été identifiés, suite à une analyse de régression logistique multivariée, comme faisant partie de groupes à risque pour la maladie étudiée (p < 0.05). Un lien avec l'activité en période de chaleurs des génisses non inséminées et une activité locomotrice généralement plus intensive des génisses par rapport aux vaches ­ avec par conséquent un risque accru de blessures ­ est concevable. Le risque était réduit pour les races à viande par rapport aux races laitières (OR 0.29). Des différences de comportement et/ou d'efficacité de l'immunité locale entre les races pourraient avoir une influence. Le fait de connaître ces groupes à risque pourrait être mis à profit à l'avenir lors de la sélection des animaux à monter à l'alpage et/ou lors de la planification de la gestion des prairies, afin de diminuer la prévalence des maladies infectieuses des onglons et ainsi l'utilisation d'antibiotiques.

In Vitro Studies of Nanoparticles as a Potentially New Antimicrobial Agent for the Prevention and Treatment of Lameness and Digital Dermatitis in Cattle.

Digital dermatitis (DD) is the second most prevalent disease in dairy cattle. It causes significant losses for dairy breeders and negatively impacts cows' welfare and milk yield. Despite this, its etiology has not been entirely identified, and available data are limited. Antibiotic therapy is a practical method for managing animal health, but overuse has caused the evolution of antibiotic-resistant bacteria, leading to a loss in antimicrobial efficacy. The antimicrobial properties of metal nanoparticles (NPs) may be a potential alternative to antibiotics. The aim of this study was to determine the biocidal properties of AgNPs, CuNPs, AuNPs, PtNPs, FeNPs, and their nanocomposites against pathogens isolated from cows suffering from hoof diseases, especially DD. The isolated pathogens included Sphingomonas paucimobilis, Ochrobactrum intermedium I, Ochrobactrum intermedium II, Ochrobactrum gallinifaecis, and Actinomyces odontolyticus. Cultures were prepared in aerobic and anaerobic environments. The viability of the pathogens was then determined after applying nanoparticles at various concentrations. The in vitro experiment showed that AgNPs and CuNPs, and their complexes, had the highest biocidal effect on pathogens. The NPs' biocidal properties and their synergistic effects were confirmed, which may forecast their use in the future treatment and the prevention of lameness in cows, especially DD.

Cost of lameness in dairy herds: An integrated bioeconomic modeling approach.

Foot disorders are costly health disorders in dairy farms, and their prevalence is related to several factors such as breed, nutrition, and farmer's management strategy. Very few modeling approaches have considered the dynamics of foot disorders and their interaction with farm management strategies within a holistic farm simulation model. The aim of this study was to estimate the cost of foot disorders in dairy herds by simulating strategies for managing lameness. A dynamic and stochastic simulation model (DairyHealthSim) was used to simulate the herd dynamics, reproduction management, and health events. A specific module was built for lameness and related herd-level management strategies. Foot disorder occurrences were simulated with a base risk for each etiology [digital dermatitis (DD), interdigital dermatitis, interdigital phlegmon, sole ulcer (SU), white line disease (WLD)]. Two state machines were implemented in the model: the first was related to the disease-induced lameness score (from 1 to 5), and the second concerned DD-state transitions. A total of 880 simulations were run to represent the combination of the following 5 scenarios: (1) housing (concrete vs. textured), (2) hygiene (2 different scraping frequencies), (3) the existence of preventive trimming, (4) different thresholds of DD prevalence detected and from which a collective footbath is applied to treat DD, and (5) farmer's ability to detect lameness (detection rate). Housing, hygiene, and trimming scenarios were associated with risk factors applied for each foot disorder etiologies. The footbath and lameness detection scenarios both determined the treatment setup and the policy of herd observance. The economic evaluation outcome was the gross margin per year. A linear regression model was run to estimate the cost per lame cow (lameness score ≥3), per case of DD and per week of a cow's medium lameness duration. The bioeconomic model reproduced a lameness prevalence varying from 26 to 98% depending on the management scenario, demonstrating a high capacity of the model to represent the diversity of the field situations. Digital dermatitis represented half of the total lameness cases, followed by interdigital dermatitis (28%), SU (19%), WLD (13%), and interdigital phlegmon (4%). The housing scenarios dramatically influenced the prevalence of SU and WLD, whereas scraping frequency and threshold for footbath application mainly determined the presence of DD. Interestingly, the results showed that preventive trimming allowed a better reduction in lameness prevalence than spending time on early detection. Scraping frequency was highly associated with DD occurrence, especially with a textured floor. The regression showed that costs were homogeneous (i.e., did not change with lameness prevalence; marginal cost equals average cost). A lame cow and a DD-affected cow cost €307.50 ± 8.40 (SD) and €391.80 ± 10.0 per year on average, respectively. The results also showed a cost of €12.10 ± 0.36 per week-cow lameness. The present estimation is the first to account for interactions between etiologies and for the complex DD dynamics with all the M-stage transitions, bringing a high level of accuracy to the results.