Progress 04/01/14 to 04/01/15
Outputs
Target Audience:Target audiences include cattle veterinarians, cattle disease diagnosticians, cattle health researchers, and cattle producers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project director (T Lehenbauer) worked closely with the graduate student (D Doyle, DVM-2013 Oklahoma State) and provided mentoring and professional guidance for the successful completion of this project which was a requirement for Dr. Doyle to earn her Master of Food Animal Medicine degree which was awarded by the University of Georgia College of Veterinary Medicine at the end of 2014. Since completion of this project, Dr. Doyle has chosen to continue her graduate academic development by enrolling in a PhD training program at Mississippi State University under Dr. Amelia Woolums as her major professor, who was also an advisor for this project. How have the results been disseminated to communities of interest?The results from this project have been published as a scientific abstract for the Research Summaries oral presentation sessions of the 48th Annual Conference of the American Association of Bovine Practitioners. A scientific abstract has been submitted for review and inclusion in the scientific program of the 2015 Conference of Research Workers in Animal Diseases (CRWAD). What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
This project was designed to provide scientific evidence for helping food animal veterinarians and other stakeholders to select the most appropriate diagnostic test for detecting microorganisms (bacteria, mycoplasma species, and viruses) that are known to cause pneumonia (bovine respiratory disease or BRD) in dairy calves. Bovine respiratory disease (BRD) is a common cause of morbidity and mortality in dairy calves and is responsible for 21% overall mortality in preweaned calves and 50% overall mortality in weaned heifers. Specifically, scientific clinical studies were conducted that compared among four different diagnostic methods for detecting disease-causing organisms associated with pneumonia in cattle. Information from this project will provide guidance for choosing between easier, simpler diagnostic methods for detecting BRD pathogens compared to other methods that take more time and effort based on the ability of these tests to detect likely causes of pneumonia in cattle. By having scientific evidence that supports use of diagnostic methods for identifying likely causes of pneumonia in dairy calves, veterinarians can strategically implement these diagnostic methods to provide information needed for developing improved treatment and prevention programs for pneumonia in dairy calves. Major Goal of the Project: To aid the rapid identification and subsequent management of bovine respiratory disease (BRD) by developing, validating and guiding the application of new or improved diagnostic tools. Four different diagnostic tools or sampling methods were scientifically validated by applying each of the four methods to each calf that had clinical signs that met the criteria needed for inclusion in the study. A total of 100 dairy calves with clinical BRD were used to scientifically compare the laboratory results among the four sampling methods. Results from this project provided scientific evidence that nasal swab (NS) and pharyngeal recess swab (PRS) sampling methods had very good agreement with bronchoaveolar lavage (BAL) and transtracheal wash (TTW) sampling methods that required more clinical skill and effort to collect a diagnostic sample for detecting pathogens that can be causes of BRD in dairy calves. Although TTW is considered to be the preferred reference standard by veterinary internal medicine specialists for obtaining the best quality samples for detecting BRD pathogens, this sampling method is invasive and requires a sterile surgical preparation and local anesthesia of the site over the trachea where the large needle is inserted and the small using is introduced in order to obtain a diagnostic sample. The BAL sampling method requires skill needed to introduce the lavage tubing through the nasal cavity and continuing into the trachea and beyond until the level of bronchi in the lungs that will accommodate the diameter of the lavage tubing is reached. With both TTW and BAL, sterile saline solution must be injected and then suction is created with a syringe attached to the tubing to retrieve a portion of the fluid that was injected which becomes the diagnostic sample for laboratory analysis. With the swab methods, single-use sterile swabs (NS) or guarded sterile swabs (PRS) are used to obtain diagnostic samples. Sampling methods using swabs are relatively simple and easy to perform while TTW and BAL require some degree of clinical veterinary skills. For the major bacterial causes of pneumonia in dairy calves, PRS and BAL showed 0.89 to 0.92 agreement beyond chance compared to the reference standard method (TTW) based on the Kappa statistic. (Nasal swab method was slightly lower at 0.86.) The percent positive agreement of these three methods compared to TTW ranged from 89% to 97%. For detection of viral pathogens, the agreement beyond chance between the different methods (NS, PRS, and BAL) compared to TTW was moderate to good but not as great as that obtained for bacterial pathogens. There were instances, however, for a number of calves (ranging from 2 to 9, depending on the viral pathogen) when these alternate methods provided positive laboratory findings when the TTW laboratory results were negative. The percent positive agreement of these three methods for detecting viral pathogens compared to TTW ranged from 57% to 93%. For detection of bovine respiratory syncytial virus (BRSV), there were numerical but non-significant advantages for BAL over swab methods and for PRS over NS. For bovine coronavirus, the PRS method detected the greatest number of calves with that virus, and all three methods identified all calves with that virus when TTW was positive. Major Goal of the Project: To facilitate the translation of research findings to practical field application by developing and integrating BRD educational programming for veterinary and producer organizations focused on cattle health and management. Results from this project have been peer-reviewed, accepted, and published as a scientific research abstract by the American Association of Bovine Practitioners (AABP) for their 48th Annual Conference. Based on the results and outcomes from this project that have been shared in educational programs for AABP, it is expected that veterinary clinicians and practitioners will apply this scientific evidence for choosing and implementing these simpler, easier, less-invasive diagnostic approaches for identifying pathogens associated with BRD in dairy calves. To the extent that these changes in approaches for BRD diagnostic testing are implemented, it is expected that improved disease prevention, control, and treatment for BRD will be achieved.
Publications
- Type: Conference Papers and Presentations
Status: Published
Year Published: 2015
Citation:
Agreement of nasal swabs, guarded nasopharyngeal swabs, and bronchoalveolar lavage relative to transtracheal wash for the diagnosis of viral and bacterial pathogens in dairy calves with bovine respiratory disease (BRD).
D.J. Doyle, DVM, MFAM 1 ; A. R. Woolums, DVM, MVSc, PhD, Dip ACVIM, Dip ACVM 1 ; B.C. Credille, DVM, PhD, Dip ACVIM 2 ; R.D. Berghaus, DVM, MS, PhD, Dip ACVPM 2 ; T.W. Lehenbauer, DVM, MPVM, PhD 3 ; S.S. Aly, BVSc, MPVM, PhD 3;
1Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762
2Department of Population Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602
3Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California, Davis, Tulare, CA, 93274
Introduction:
Four sampling methods are used for antemortem identification of respiratory pathogens: the nasal swab (NS), guarded nasopharyngeal swab (NPS), transtracheal wash (TTW), and bronchoalveolar lavage (BAL). The TTW bypasses contamination from the nasopharynx, but the procedure is invasive and requires technical skill. The BAL and TTW directly sample the lower airways, but BAL, NS, and NPS can be contaminated by nasopharyngeal flora. Compared to NS, NPS provides a guarded sample of the pharyngeal recess, which may be more representative of BRD pathogens. The objective of this study was to compare the agreement of results obtained by NS, NPS, or BAL with those obtained by TTW for isolation of BRD pathogens in dairy calves with acute undifferentiated BRD.
Materials and Methods:
Subject calves were housed on a privately owned calf rearing facility in Tulare, CA. All calves with primary naturally occurring respiratory disease in the first 90 days of life, as defined by a score of 5 or greater on the University of Wisconsin Calf Respiratory Scoring Chart, a fever of 103 ?F or higher, and at least 2 cm2 of pulmonary consolidation identified by transthoracic ultrasound, were eligible for enrollment. Calves that had been treated for respiratory disease at any time, or calves that had been given intranasal modified live viral respiratory vaccine in the previous 30 days, were excluded. From each calf enrolled, NS, NPS, TTW, and BAL samples were collected sequentially using standard methods. All samples were tested by aerobic bacterial culture and real time reverse transcriptase PCR for bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCV), bovine viral diarrhea virus (BVDV), and bovine herpesvirus-1 (BHV-1). For each pathogen, agreement between tests and a comparison of positive results was determined by calculation of the kappa statistic and McNemars chi-square test. Kappa values were interpreted to indicate strength of agreement as defined by Altman (1991): less than 0.20 = poor; 0.21 - 0.40 = fair; 0.41 - 0.6 = moderate; 0.61 - 0.80 = good, and 0.81 - 1.00 = very good.
Results:
One hundred calves were enrolled. Average calf age was 49 days, average rectal temperature was 103.8� F, average respiratory score was 10, and an average of 22.1 cm2 of lung consolidation was identified by ultrasound. The prevalence of pathogens identified by TTW was: 6.6% for BCV, 17.4% for BRSV, 16.0% for M. haemolytica, and 59.0% for P. multocida. No samples were positive for BHV-1, BVDV, or H. somni.
When M. haemolytica and P. multocida were isolated, all methods showed very good agreement relative to the TTW. When BRSV was detected, the NS had moderate agreement, the NPS had good agreement, and the BAL had very good agreement. Lastly, when BCV was detected, the NS and NPS had moderate agreement while the BAL had good agreement.
- Significance:
All four methods yielded similar results for detection of M. haemolytica and P. multocida, while BAL had better agreement relative to swabs when compared to TTW for detection of BRSV and BCV.
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