Digital dermatitis (DD) is an ulcerative foot lesion on the heel bulbs of dairy cattle. DD is a polymicrobial disease with no precise etiology, although Treponema spirochetes are found disproportionally abundant in diseased tissue. Within Treponema, several different species are found in DD; however, the species Treponema phagedenis is uniformly found in copious quantities and deep within the skin layers of the active, ulcerative stages of disease. The pathogenic mechanisms these bacteria use to persist in the skin and the precise role they play in the pathology of DD are widely unknown. To explore the pathogenesis and virulence of Treponema phagedenis, newly isolated strains of this species were investigated in a subcutaneous murine abscess model. In the first trial, a dosage study was conducted to compare the pathogenicity of different strains across three different treponemes per inoculum (TPI) doses based on abscess volumes. In the second trial, the expression levels of 11 putative virulence genes were obtained to gain insight into their involvement in pathogenesis. During the RT-qPCR analysis, it was determined that genes encoding for two metal-ion import lipoproteins and two adherence genes were found highly upregulated during infection. Conversely, two genes involved in motility and chemotaxis were found to not be significantly upregulated or utilized during infection. These results were supported by gene expression data from natural M2 lesions of dairy cattle. This gene expression analysis could highlight the preference in strategy for T. phagedenis to persist and adhere in the host rather than engage in motility and disseminate.

BACKGROUND: Digital dermatitis (DD) is a contagious bovine foot disease causing reduced animal welfare and negative economic consequences for the farmer. Treponema spp. are the most important causative agents. Studies indicate that trimming equipment can transfer DD-associated treponemes between cows. The aim of this observational study in 22 DD-positive Norwegian dairy herds was to investigate the risk of transferring Treponema spp. with trimming equipment and chutes after claw trimming, and after washing and disinfection. Swabs from the trimming equipment and chutes were collected from nine different locations, at five different time points. Bacterial DNA was extracted from 647 swabs and analysed by qPCR for Treponema spp. In addition, 172 swabs taken immediately after trimming, were analysed by a multiplex qPCR targeting T. phagedenis, T. pedis and T. medium/vincentii. Biopsy sampling from DD lesions was performed on cows in the same herds during trimming. Altogether 109 biopsies were analysed by FISH for confirmation of the DD diagnosis and identification of Treponema phylotypes (PTs).
RESULTS: High numbers of Treponema spp. were detected from all nine locations on the trimming equipment and chutes immediately after trimming, and T. phagedenis was detected on two or more locations in all but two herds, 1 and 19. There was a decline in the amount of Treponema spp. after washing and disinfection. The belly belt, the cuff, and the footrest on the chute had the highest proportion of positive samples after disinfection. The belly belt had the highest copy numbers of all nine locations (median = 7.9, max = 545.1). No Treponema spp. was detected on the hoof knives after disinfection. Treponema phagedenis, T. pedis, and Treponema phylotype 3 (T. refringens) were detected by FISH analysis of the biopsies. Treponema phagedenis was detected in biopsies from all herds except 1 and 19.
CONCLUSIONS: This study shows that DD-associated Treponema spp. were present on the trimming equipment and chutes after trimming cows in DD-positive herds. Washing and disinfection reduced the load of Treponema spp. However, large differences in Treponema spp. between different locations were documented. High copy numbers on the grinder and the chute after disinfection, indicates that sufficient cleaning and disinfection of these locations is difficult, and that passive transfer of DD-associated treponemes (viable or not) is possible.

The control of digital dermatitis (DD) among cattle is crucial; however, effective and environmentally-sound control measures have yet to be identified. From the monitoring data of DD which were recorded during regular hoof trimmings in a farm in Hokkaido, Japan, we detected a decrease in the DD prevalence in a herd where an anaerobic bacterial fermentation enhancer (ABFE) was distributed. The possible effect of ABFE was analyzed using a retrospective repeated cross-sectional design. The prevalence of DD decreased over time in the ABFE-distributed group. Furthermore, a selected regression model indicated the time-dependent enhancement of the decreasing trend. While potential coincidental factors may influence, this study provides a basis for further research on the preventive effect of ABFE against DD.

Digital dermatitis (DD) is a bovine claw disease responsible for ulcerative lesions on the planar aspect of the hoof. DD is associated with massive herd outbreaks of lameness and influences cattle welfare and production. Early detection of DD can lead to prompt treatment and decrease lameness. Computer vision (CV) provides a unique opportunity to improve early detection. The study aims to train and compare applications for the real-time detection of DD in dairy cows. Eight CV models were trained for detection and scoring, compared using performance metrics and inference time, and the best model was automated for real-time detection using images and video. Images were collected from commercial dairy farms while facing the interdigital space on the plantar surface of the foot. Images were scored for M-stages of DD by a trained investigator using the M-stage DD classification system with distinct labels for hyperkeratosis (H) and proliferations (P). Two sets of images were compiled: the first dataset (Dataset 1) containing 1,177 M0/M4H and 1,050 M2/M2P images and the second dataset (Dataset 2) containing 240 M0, 17 M2, 51 M2P, 114 M4H, and 108 M4P images. Models were trained to detect and score DD lesions and compared for precision, recall, and mean average precision (mAP) in addition to inference time in frame per second (FPS). Seven of the nine CV models performed well compared to the ground truth of labeled images using Dataset 1. The six models, Faster R-CNN, Cascade R-CNN, YOLOv3, Tiny YOLOv3, YOLOv4, Tiny YOLOv4, and YOLOv5s achieved an mAP between 0.964 and 0.998, whereas the other two models, SSD and SSD Lite, yielded an mAP of 0.371 and 0.387 respectively. Overall, YOLOv4, Tiny YOLOv4, and YOLOv5s outperformed all other models with almost perfect precision, perfect recall, and a higher mAP. Tiny YOLOv4 outperformed all other models with respect to inference time at 333 FPS, followed by YOLOv5s at 133 FPS and YOLOv4 at 65 FPS. YOLOv4 and Tiny YOLOv4 performed better than YOLOv5s compared to the ground truth using Dataset 2. YOLOv4 and Tiny YOLOv4 yielded a similar mAP of 0.896 and 0.895, respectively. However, Tiny YOLOv4 achieved both higher precision and recall compared to YOLOv4. Finally, Tiny YOLOv4 was able to detect DD lesions on a commercial dairy farm with high performance and speed. The proposed CV tool can be used for early detection and prompt treatment of DD in dairy cows. This result is a step towards applying CV algorithms to veterinary medicine and implementing real-time DD detection on dairy farms.

Lameness, mostly resulting from claw lesions, causes major welfare problems in the dairy industry. One way to prevent claw lesions is hoof trimming, but the overall effect and the optimal hoof trimming frequency are unknown. In a retrospective cohort study, we investigated the association between hoof trimming frequency in primiparous cows and hoof health and culling in second lactation. We based our analysis on breed, calving and culling data in the period 2015-2018 for 30,613 primiparous cows in 202 Swedish dairy herds. Of the cows enrolled, 20% were not hoof-trimmed, 30% were trimmed once, 34% were trimmed twice, 13% were trimmed 3 times, and 2% were trimmed ≥ 4 times. We used multivariable mixed-effect logistic and multivariable multinomial logistic regression models to investigate the association between trimming frequency and 2 outcomes: hoof lesions at first trimming occasion within 90 d from second calving and culling in second lactation within 300 d after second calving. In general, cows trimmed 2 or 3 times during first lactation were at lower odds of having claw lesions compared with cows that were not trimmed (Odds Ratio (OR) = 0.66, 95% CI = 0.62-0.71 and 0.60, 95% CI = 0.55-0.66, respectively) or cows trimmed once (OR = 0.80, 95% CI = 0.75-0.85 and OR = 0.72, 95% CI = 0.66-0.79, respectively), and this beneficial effect was observed for most types of claw lesions. Moreover, cows trimmed 2, 3, or ≥ 4 times were at lower odds of being culled compared with cows that were not trimmed (OR = 0.71, 95% CI = 0.65-0.77, 0.68, 95% CI = 0.61-0.76 and 0.70, 95% CI = 0.54-0.90, respectively) or trimmed once (OR = 0.77, 95% CI = 0.71-0.83, OR = 0.74, 95% CI = 0.66-0.82 and OR = 0.75, 95% CI = 0.59-0.97, respectively). In particular, 2 trimmings, compared with 1 or no trimming, lowered the relative risk-ratio of dying or being euthanized on-farm, or being culled due to claw and leg disorders. More than 1 hoof trimming in first lactation also reduced the relative-risk ratio of being culled for other reasons. In conclusion, 2 or 3 hoof trimmings during first lactation were generally beneficial for hoof health in early second lactation and survival in second lactation. These findings can help improve animal welfare and production by reducing claw lesions, and thereby lameness among dairy cows, which would increase the longevity of dairy cows and the sustainability of the dairy industry.

Bovine digital dermatitis remains a widespread endemic disease of dairy cattle worldwide. Footbathing is commonly used as a control measure and has significant economic and environmental impact. There are few studies documenting footbathing practices on dairy farms, or evaluating their suitability for achieving foot disinfection. This study describes footbathing practices on 32 farms observed in the United Kingdom, Ireland, and the Netherlands. We measured solution depth throughout footbathing and observed levels below 7cm on 9/32 farms, which leads to inadequate foot coverage. Solution depth was associated with the number of cow passages, decreasing by 1.2cm for every 100 cow passages. We also describe levels of organic matter content (g/L) throughout footbathing as a proxy for footbath hygiene. Our data indicates that almost half of footbaths (15/32) became contaminated above the 20g/L threshold to which veterinary biocides are tested for efficacy, and that organic matter content is associated with the number of cow passages per liter of footbathing solution provided. A multivariable mixed model predicted that one liter of footbathing solution per cow should be sufficient to prevent excess contamination. As a further measure of hygiene, we tested a subset of footbath samples to quantify the amount of DNA present from the Treponema species which are considered instrumental in the etiology of digital dermatitis. We did not detect Treponema DNA in footbath samples, suggesting they are unlikely to act as infection reservoirs for this disease. Multivariable mixed models including farm identity as a random effect demonstrated that for both change in solution depth and organic matter content the effect of farm-level factors was large. Because of the magnitude of this farm effect, applying model predictions will not translate to adequate solution depth and hygiene on all farms. Our data highlights the importance of footbath auditing on individual farms.

Bovine ischaemic teat necrosis (ITN) is a disease affecting the skin of the teats of dairy cows with an unknown aetiopathogenesis. Digital dermatitis (DD)-associated treponemes have previously been suggested as a potential aetiological agent in ITN, although the sample size was small. The current study, using established PCR techniques, aimed to examine the association with the presence of DD-associated treponemes in a large number of ITN samples from a wider geographical area, and surveyed the potential of milk as an infection reservoir. From 95 ITN lesions, 35.8% (n = 34) were positive for at least one DD-associated treponeme compared with only 5.6% (n = 1) of 18 non-lesioned teats from cows with ITN lesions on a different teat using a nested PCR approach. All 10 age- and production-matched control cows were negative for DD-associated treponemes via PCR. No DD-associated treponemes could be detected from foremilk of cows with (n = 19) and without (n = 31) a DD lesion on the hind feet. DD-associated treponemes could be detected via PCR after incubation in milk for up to 2 h. Therefore, milk does not appear to be a competent reservoir for transmission of DD-associated treponemes. Moreover, in the current study DD-associated treponemes were only detected in a subset of ITN samples, so it is unlikely these opportunistic skin-associated pathogens are the major or sole agent of ITN.

BACKGROUND: Digital dermatitis (DD) is a contagious hoof infection affecting cattle worldwide. The disease causes lameness and a reduction in animal welfare, which ultimately leads to major decreases in milk production in dairy cattle. The disease is most likely of polymicrobial origin with Treponema phagedenis and other Treponema spp. playing a key role; however, the etiology is not fully understood. Diagnosis of the disease is based on visual assessment of the feet by trained hoof-trimmers and veterinarians, as a more reliable diagnostic method is lacking. The aim of this study was to evaluate the use of an enzyme-linked immunosorbent assay (ELISA) on bulk tank milk samples testing for the presence of T. phagedenis antibodies as a proxy to assess herd prevalence of DD in Swedish dairy cattle herds.
RESULTS: Bulk tank milk samples were collected in 2013 from 612 dairy herds spread across Sweden. A nationwide DD apparent prevalence of 11.9% (8.1-14.4% CI95%) was found, with the highest proportion of test-positive herds in the South Swedish regions (31.3%; 19.9-42.4% CI95%).
CONCLUSIONS: This study reveals an underestimation of DD prevalence based on test results compared to hoof trimming data, highlighting the critical need for a reliable and accurate diagnostic method. Such a method is essential for disease monitoring and the development of effective control strategies. The novelty of ELISA-based diagnostic methods for DD, coupled with the disease\'s polymicrobial origin, suggests an avenue for improvement. Developing an expanded ELISA, incorporating antigens from various bacterial species implicated in the disease, could enhance diagnostic accuracy. The significance of this study is underscored by the extensive analysis of a substantial sample size (612). Notably, this investigation stands as the largest assessment to date, evaluating the application of ELISA on bulk tank milk for DD diagnosis at the herd level.

The objective of this study was to determine whether a novel footbath solution containing stannous fluoride (SnF2) was superior to 5% copper sulfate solution for the treatment and prevention of digital dermatitis (DD) in dairy cattle. Study 1 was conducted over 4 weeks in Missouri and involved 34 lactating Holstein-Friesian cows with hind feet DD lesions. Cows in group SF walked through a footbath containing a proprietary formulation of SnF2 once weekly, whereas cows in group CS walked through a 5% CuSO4 footbath once daily for 5 d each week. Study 2 was conducted over 8 weeks in California and involved 40 lactating Holstein-Friesian cows with hind feet DD lesions. Cows in group SF walked through a SnF2 footbath for 3 consecutive days then once a week for the following 7 weeks. Cows in group CS walked through a 5% CuSO4 footbath 3 times each week for 8 weeks. Data collection included lesion type, lesion area, locomotion score, and pain score. Digital dermatitis was actively transmitted in study 1, and lesion area and locomotion scores were lower in group SF than group CS. In contrast, DD was not actively transmitted in study 2, and lesion area and locomotion scores were similar in groups SF and CS. Stannous fluoride delayed the development of active DD lesions in study 1 compared with copper sulfate, with a lower relative risk (0.57, P < 0.001) of a hind foot developing an active DD lesion over 28 d. However, SnF2 decreased the rate that active DD lesions transitioned to M3, M4, or M0 lesions compared with 5% copper sulfate in both studies, with the relative risk of a hind foot with an active DD lesion transitioning to M3, M4, or M0 in group SF being slightly lower in study 1 (0.83, P = 0.042) and study 2 (0.90, P = 0.020) than group CS. Our findings demonstrated that walking cows through a stannous fluoride footbath once per week in a herd undergoing active transmission of infection was more effective in preventing active DD lesions, but less effective in treating active DD lesions, than walking cows through a copper sulfate footbath 4 times per week. The novel SnF2 footbath solution shows promise for controlling DD in dairy herds that want an alternative footbath solution to CuSO4 and are interested in limiting the environmental accumulation of copper.

BACKGROUND: Treponeme-Associated Hoof Disease (TAHD) is a polybacterial, multifactorial disease affecting free-ranging wild elk (Cervus canadensis) in the Pacific Northwest. Previous studies have indicated a bacterial etiology similar to digital dermatitis in livestock, including isolation of Treponema species from lesions. The lesions appear to progress rapidly from ulcerative areas in the interdigital space or along the coronary band to severe, ulcerative, necrotic, proliferative lesions under-running the hoof wall, perforating the sole, and contributing to hoof elongation, deformity, and overgrowth. Eventually the lesions undermine the laminal structure leading to sloughing of the hoof horn capsule. The objective of this study was to characterize the bacterial communities associated with hoof lesions, which were categorized into 5 stages or disease grade severities, with 0 being unaffected tissue and 4 being sloughed hoof capsule. We also wanted to determine if the etiology of TAHD through morphological changes was dominated by Treponema, as observed in hoof diseases in livestock.
RESULTS: The bacterial 16S rRNA gene was sequenced from 66 hoof skin biopsy samples representing 5 lesion grades from samples collected by Washington Department of Fish and Wildlife as part of a voluntary hunter program. Analysis of the relative abundance of bacterial sequences showed that lesions were dominated by members of the bacterial phyla Proteobacteria, Firmicutes, Spirochaetes, Bacteroidetes and Actinobacteria. In lesion samples, members of the genus Treponema, Porphyromonas, and Mycoplasma increased with lesion severity. Association analysis indicated frequent identification of Treponema with Porphyromonas, Bacteroides and other anaerobic Gram-positive cocci.
CONCLUSIONS: The bacterial 16S rRNA gene sequencing confirmed the presence of Treponema species at all stages of TAHD lesions, treponeme specie-specific PCR and histopathology, indicating that the morphological changes are a continual progression of disease severity with similar bacterial communities. Association and abundance of these other pathogenic genera within lesions may mean synergistic role with Treponema in hoof disease pathogenesis. Characterizing bacteria involved in lesion development, and their persistence during disease progression, provides evidence for science-based management decisions in TAHD infected elk populations.