Progress 03/01/15 to 02/28/19
Outputs
Target Audience:Veterinarians, dairy and beef farmers, animal scientist, veterinary microbiologist Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A full time graduate student focused on this project was employed for three years and used this project as the basis for his PhD thesis. Given that he already had a DVM, his training provided by this project will provide him a strong basis for becoming a very effective clinician-scientist. At the conclusion of this project we has accepted a job on the veterinary faculty of a College of Veterinary Medicine. In addition the project provided funds for hiring three veterinary students to work on the project over the summer and in their free time during the school year. That experience provided them valuable exposure to veterinary medical research, evidence based medicine and research design. In addition, a total of 4 veterinary summer scholars participated in this project as part of their 10 week summer research experience. Finally, two undergraduate students were employed on an as needed hourly basis to assist with sample collection and processing. On the professional development side this project has formed the basis for over 10 oral presentations given to veterinary continuing education conferences (International Ruminant Lameness Conference, Academy of Veterinary Consultants, and two talks at the American Association of Bovine Practitioners) and four additional poster presentations. These talks allowed the information gained to be disseminated to the veterinary community and to impact clinical decision making at the farm level. Additionally, these presentations allowed for the graduate student to gain experience in presenting at national and international meetings. How have the results been disseminated to communities of interest?To date, over 10 oral presentations have been given to veterinary continuing education conferences (International Ruminant Lameness Conference, Academy of Veterinary Consultants, and two talks at the American Association of Bovine Practitioners) and four additional poster presentations. To date two peer-reviewed manuscripts have been published Krull A, Cooper V, Shearer J, Gorden P, Plummer PJ. A Highly Effective Protocol for the Rapid and Consistent Induction of Digital Dermatitis in Holstein Calves. Plos One. 11(4): e0154481. doi:10.1371/journal. pone.0154481 Krull A, Shearer J, Gorden P, Scott HM, Plummer PJ. Digital Dermatitis: Natural Lesion Progression and Regression in Holstein Dairy Cattle Over Three Years. Journal of Dairy Science. 99:1-14 http://dx.doi.org/10.3168/jds.2015-1053 Currently, at least five additional peer reviewed manuscripts are in preparation and are anticipated to be published in peer review journals in the coming months. Finally, given that the Co-PI has an extension veterinary program, the Master Hoof Care Technician Program, this information has been incorporated and widely disseminated to producers and foot trimmers around North America. This program certified hundreds of participants that use these interventions on a regular basis and as a consequence the outcomes of these studies are widely known and used in clinical medicine and treatment. What do you plan to do during the next reporting period to accomplish the goals?This is the final report and no additional reporting is anticipated.
Impacts
What was accomplished under these goals?
First, we completed a metagenomic evaluation of the dairy farm environment designed to evaluate the environmental reservoirs and sources of infection. Based on the findings of that study we have identified animals, foot trimming equipment and human work areas as having the highest number read counts associated with DD bacteria. In addition we did identify the presence of DD associated bacteria, and specifically DD associated Treponema spp., in manure slurry, bedding and on farm equipment. However, the relative abundance of these organisms was lower in these environments. Based on this data we can see that control efforts need to focus on animal sources and foot trimming equipment, however other environmental sources do harbor the organism and likely act as a smaller risk exposure source. Second, we completed a prospective randomized clinical control trial designed to compare the efficacy of a single application of tetracycline to three repeated applications of tetracycline for treatment success in active DD lesions. The purpose of this prospective trial was to determine if more aggressive antibiotic treatment would result in better healing of advanced DD lesions, which seem to be a chronic source of bacterial contamination based on the study of the environment. Cows with active DD lesions were enrolled and randomized to one of two treatment groups. One group received a single topical application of oxytetracycline powder applied to the lesion followed by a light wrap. The other received three sequential topical applications at approximately 1-week intervals. At day 120, only 5 of 31 lesions had healed to normal skin following treatment (3 single and 2 triple). The majority of the lesions were still present, mostly as early stage lesions. The average lesion score decreases in both groups over the first 60 days, but begins to rise again by day 120. There was no significant difference between lesion scores in the two treatment groups on either day 60 or day 120 post-enrollment. Both single and triple treatments did however eliminate significant lameness attributed to DD. There are significant differences between pressure algometer scores based on lesion score, but no significant difference in the two treatment groups on day 120 post-enrollment. While both a single treatment with topical oxytetracycline and three consecutive weekly treatments effectively resolve clinical lameness for the duration of the study, neither treatment appears to offer consistent, long-term resolution of digital dermatitis lesions. It is apparent in nearly all cases that a "scab" forms shortly after treatment, suggesting that the lesion is in the process of resolving; however, in the majority of cases the lesion remains present or progresses long after the "scab" is gone. Further analysis of these lesions is underway to evaluate the role of the microbiome in lesion improvement. Third, we performed a study to determine whether the application of a well-managed footbath containing 3% formalin halts the development and encourages the resolution of early stage DD lesions better than no therapy. These lesions stages are early than described by previous DD staging systems and evaluated in DD footbath studies, making this a novel approach. 54 total early stage lesions were identified at day 0. 37% returned to normal skin at 6 weeks post-enrollment (two weeks post footbath). Approximately twice as many lesions that were treated returned to normal skin compared to the control group. There was a significant difference between the decrease in severity noted in lesions in the treatment group over the course of the study vs. the control group (p = 0.009). In addition, of the 15 advanced lesions enrolled (because the opposite hind foot contained an early lesion) the majority of them remained advanced lesions at the conclusion of the study. The results indicate that a 3% formalin footbath, applied three times week for four weeks, significantly reduces the average lesion score for early lesions. However, there is no appreciable change in the average lesion score for advanced lesions, suggesting that footbaths are most effective at control of early stage lesions. The results also suggest that early lesions respond differently than advanced lesions, and consequently, evaluating them separately is critical in footbath studies. We also performed a study to evaluate the changes in environmental and foot-associated microbial communities following environmental exposure to advanced DD lesions. We hypothesize that introduction of cattle with DD lesions into a "naïve" environment will result in measurable changes in the relative abundance of DD associated bacteria in environmental samples. Likewise, we hypothesize that introduction of "clean" cattle into an "infected" environment will result in measurable and consistent changes in the skin flora of the cattle foot. The study design used a basic crossover design and will be conducted in a controlled environment that allows for complete cleaning and disinfection prior to animal introduction. Two identical pens were used for the study. Each group of calves was housed in their respective pens for 7 days prior to the start of the study in order for baseline dairy slurry to develop and accumulate in the environment. On day one of the study, environmental samples of the fecal slurry, water source, bedding and feed pans were collected and frozen for metagenomic analysis. Likewise each calf had a swab of the caudal aspect of the foot, a swab of the interdigital fold, a swab of saliva and a biopsy of the caudal aspect of the foot collected for metagenomics. These samples acted as the baseline samples for animal-associated and environmental samples from the "clean" and "infected" pens. The cattle were then switched to the opposite pens. Identical samples to those described above were collected weekly for a total of three weeks. Metagenomic analysis of the samples is ongoing and will be completed in the near future. In order to further evaluate the role of encysted Treponema spp. in the ecology of this disease process we have been working to better understand these "round-body" form of the organism. We have been using a variety of techniques to evaluate the viability and metabolic function of these cells including methods of determining cellular respiration, cell membrane integrity, electron transport chain and electron microscopy. These studies have supported the hypothesis that the round body forms do not show evidence of viability. They fail to have evidence of cellular respiration and are not able to maintain their membrane potential. These findings bring into question the role of encysted Treponemes in the DD disease ecology. The techniques used above to study the encysted cell were also evaluated to as a potential means of evaluating footbath efficacy in vitro. The goal was to determine if these approaches would allow for real-time evaluation of kill curves using common footbath treatments. Unfortunately, while the live dead staining procedure was effective in the control samples, the addition of the disinfectants resulted in a loss of signal. It is unclear if this loss of signal was associated with chemical interaction of the disinfectants with the stain or due to an unexpected impact on the bacterial cells themselves. As a result, these approaches were largely found to be unacceptable as a means of evaluating footbath efficacy. Finally, we evaluated the metagenomic bacterial composition of feedlot cattle compared to dairy cattle. This was performed by sampling random DD lesions in beef cattle arriving at a feedlot and over time. The sample collection and analysis of this study is ongoing and is anticipated to be completed in the next year. Preliminary data suggest that while the samples have significant similarity to dairy cattle DD samples, there are some notable differences. The results of that study will be disseminated when completed.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Krull A, Cooper V, Shearer J, Gorden P, Plummer PJ. A Highly Effective Protocol for the Rapid and Consistent Induction of Digital Dermatitis in Holstein Calves. Plos One. 11(4): e0154481. doi:10.1371/journal. pone.0154481
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Krull A, Shearer J, Gorden P, Scott HM, Plummer PJ. Digital Dermatitis: Natural Lesion Progression and Regression in Holstein Dairy Cattle Over Three Years. Journal of Dairy Science. 99:114 http://dx.doi.org/10.3168/jds.2015-1053
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Progress 03/01/15 to 02/29/16
Outputs
Target Audience:Veterinarians, dairy and beef farmers, animal scientist, veterinary microbiologist Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?A full time graduate student focused on this project has been hired and is using this project as the basis for his PhD thesis. Given that he already has a DVM, his training provided by this project will provide him a strong basis for becoming a very effective clinician-scientist. In addition the project has provided funds for hiring three veterinary students to work on the project over the summer and in free time during the school year. That experience is providing them valuable exposure to veterinary medical research, evidence based medicine and research design. Finally, two undergraduate students are employed on an as needed hourly basis to assist with sample collection and processing. On the professional development side this project has formed the basis for four oral presentations given to veterinary continuing education conferences (International Ruminant Lameness Conference, Academy of Veterinary Consultants, and two talks at the American Association of Bovine Practitioners) and two additional poster presentations. These talks are allowing the information gained to be disseminated to the veterinary community and to impact clinical decision making at the farm level. How have the results been disseminated to communities of interest? To peer-reviewed manuscripts have been published o Krull A, Cooper V, Shearer J, Gorden P, Plummer PJ. A Highly Effective Protocol for the Rapid and Consistent Induction of Digital Dermatitis in Holstein Calves. Plos One. 11(4): e0154481. doi:10.1371/journal. pone.0154481 o Krull A, Shearer J, Gorden P, Scott HM, Plummer PJ. Digital Dermatitis: Natural Lesion Progression and Regression in Holstein Dairy Cattle Over Three Years. Journal of Dairy Science. 99:1-14 http://dx.doi.org/10.3168/jds.2015-1053 As mentioned above four oral presentations to veterinary continuing education conferences have been presented related to this project. Rock C, Krull A, Gorden P, Shearer J, Plummer P. METAGENOMIC EVALUATION OF THE DAIRY FARM ENVIRONMENT AND FACILITIES FOR EVIDENCE OF DIGITAL DERMATITIS ASSOCIATED BACTERIA. 10th International Conference on Lameness in Ruminants. Valdivia-Chile Nov 22-25, 2015. Plummer P. Update on Digital Dermatitis Pathophysiology, Development and Etiology. Academy of Veterinary Consultants, Kansas City, MO August 5, 2016 Krull A, Shearer J, Gorden P, Cooper V, Plummer P. DEEP SEQUENCING METAGENOMIC ANALYSIS OF EXPERIMENTALLY INDUCED BOVINE DIGITAL DERMATITIS LESIONS. AABP Conference, Charlotte, NC. September 17, 2016 Rock C, Krull A, Gorden P, Shearer J, Plummer P. METAGENOMIC EVALUATION OF THE DAIRY FARM ENVIRONMENT AND FACILITIES FOR EVIDENCE OF DIGITAL DERMATITIS ASSOCIATED BACTERIA. AABP Conference, Charlotte, NC. September 17, 2016 Three poster presentations have been made Adam C. Krull, Vickie L. Cooper, John Coatney, Jan K. Shearer, Patrick J. Gorden, and Paul J. Plummer. Experimental Induction of Bovine Digital Dermatitis Lesions in Naïve Dairy Calves. 10th International Conference on Lameness in Ruminants. Valdivia-Chile Nov 22-25, 2015. Coatney J, Wilson-Welder J, Krull A, Gorden P, Shearer J, Plummer P. EVALUATION OF THE IMMUNE RESPONSE TO BOVINE DIGITAL DERMATITIS ASSOCIATED BACTERIA FOLLOWING EXPERIMENTAL INDUCTION OF DISEASE AND SUBSEQUENT RE-CHALLENGE. 10th International Conference on Lameness in Ruminants. Valdivia-Chile Nov 22-25, 2015. Krull A, Shearer J, Gorden P, Cooper V, Plummer P. DEEP SEQUENCING METAGENOMIC ANALYSIS OF EXPERIMENTALLY INDUCED BOVINE DIGITAL DERMATITIS LESIONS. 10th International Conference on Lameness in Ruminants. Valdivia-Chile Nov 22-25, 2015. One press release issued by Iowa State related to the publication of the epidemiology paper resulted in several news agency reports, inclusion of the press release in Bovine Veterinarian magazine and a tweet from USDA NIFA. What do you plan to do during the next reporting period to accomplish the goals?We plan to continue the progress on all three objectives. Specifically we anticipate completion of most of the subobjectives in objective 1, and many of the subobjectives in objective 2. We will continue to enroll cattle in the prospective trial, as well as the footbath trial. Likewise we will be conducting the footbath testing outlined in objective 2. Finally we will work to finalize study site and plan for the beef study in objective 3.
Impacts
What was accomplished under these goals?
During the reporting period significant progress has been made on the completion of objectives 1 and 2. We completed a metagenomic evaluation of the dairy farm environment designed to evaluate the environmental reservoirs and sources of infection. Based on the findings of that study we have identified animals (DD lesions, ulcerative mammary dermatitis, and the rectum), foot trimming equipment and human work areas (computer keyboards, office floors etc) as having the highest number read counts associated with DD bacteria. In addition we did identify the presence of DD associated bacteria, and specifically DD associated Treponema spp., in manure slurry, bedding and on farm equipment. However, the relative abundance of these organisms was lower in these environments. Based on this data we can see that control efforts need to focus on animal sources and foot trimming equipment, however other environmental sources do harbor the organism and likely act as a smaller risk exposure source. We also have enrolled approximately 2/3 of the cattle in the prospective randomized control trial designed to compare the efficacy of a single application of tetracycline to three repeated applications of tetracycline for treatment success in active DD lesions. These animals will be followed for approximately six months and additional enrollment of animals is underway as cases are identified. To further evaluate the role of encysted Treponema spp. in the ecology of this disease process we have been working to better understand these "round-body" form of the organism. We have been using a variety of techniques to evaluate the viability and metabolic function of these cells including methods of determining cellular respiration, cell membrane integrity, electron transport chain and electron microscopy. These studies are underway and data collection is progressing well. The techniques used in the study of encysted cells are also being evaluated to select the best means of comparing footbath efficacy in the second objective. We have developed protocols to proceed with these evaluations and sample collection and technique validation are in process.
Publications
- Type:
Journal Articles
Status:
Under Review
Year Published:
2016
Citation:
Krull A, Cooper V, Shearer J, Gorden P, Plummer PJ. A Highly Effective Protocol for the Rapid and Consistent Induction of Digital Dermatitis in Holstein Calves. Plos One. 11(4): e0154481. doi:10.1371/journal. pone.0154481
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Krull A, Shearer J, Gorden P, Scott HM, Plummer PJ. Digital Dermatitis: Natural Lesion Progression and Regression in Holstein Dairy Cattle Over Three Years. Journal of Dairy Science. 99:114 http://dx.doi.org/10.3168/jds.2015-1053
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