2019 American Dairy Science Association (ADSA)
Guiding antimicrobial therapy: Prevalence of bacteremia in dairy calves with diarrhea.
J. Garcia*, J. Pempek, A. Hinds, D. Diaz-Campos, and G. Habing
Calfhood diarrhea is the most common cause of mortality in dairy calves. Septicemia is an important sequela of diarrhea, and the primary justification for antimicrobial treatment for diarrhea. Farm workers make routine decisions to initiate antimicrobial therapy based on clinical signs, yet there is a lack of criteria associated with bacteremia. The prevalence of bacteremia in diarrheic calves has been estimated to be 30%; however, this estimate included calves presented to a veterinary hospital or raised for veal, and may not reflect the prevalence in calves on commercial dairy operations. Thus, the objective of this study was to determine the prevalence of bacteremia in diarrheic dairy calves and identify clinical signs associated with bacteremia. We hypothesized that the prevalence of bacteremia would be less than 30% in calves with diarrhea, and that clinical signs, such as temperature and respiratory rate, would be accurate predictors of bacteremia. Calves (≤21 d of age) were enrolled across 2 dairy farms into a diarrheic or clinically healthy group. Diarrheic calves enrolled presented with loose to watery stool, dehydration (assessed by skin tent) or depression (assessed by suckle reflex and ability to stand), and were not previously treated with antibiotics. Health assessments were performed at enrollment, and included respiratory signs, joint inflammation, navel score, temperature, and heart and respiratory rate. Following the health assessment, one aseptic blood sample was collected from each calf and cultured to determine bacterial species present using mass spectrometry. Associations between bacteremia and dichotomized health outcomes were analyzed using Fisher’s exact tests and continuous outcomes were compared using Student’s t-tests. The prevalence of bacteremia in diarrheic calves was 15.3% (17/111) and 18.5% (5/27) in clinically healthy calves. There was no association between clinical signs and bacteremia. The prevalence of bacteremia in the diarrheic group was significantly lower than previous estimates, indicating there may be opportunity to reduce antimicrobial use in calves with diarrhea that are not septicemic.
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Prevalence of five enteric pathogens on Ohio dairy farms.
J. Barkley*, J. Pempek, A. Bowman, J. Nolting, J. Lee, S. Lee, and G. Habing
Calf diarrhea remains one of the main reasons for productivity and economic losses on US dairy operations. The majority of pre-weaned calf mortality (56.4%) is attributed to diarrhea or other digestive problems (USDA, 2014). Five enteric pathogens are commonly associated with diarrhea in dairy calves, including bovine rotavirus, bovine coronavirus, Escherichia coli, Salmonella spp., and Cryptosporidium parvum. However, pathogen-associated differences in health outcomes and case fatality rates have not been well characterized. The objective of this study was to estimate the prevalence of diarrheal pathogens on Ohio dairy farms, and longitudinally measure the health outcomes for diarrheal illnesses. For this study, fecal samples were collected from277 clinically ill calves across 5 different farms on the first day of diarrheal diagnosis. Genomic techniques, including RT-PCR and ddPCR were used to test for the presence of the 5 enteric pathogens. A Poisson regression model was used to analyze the relative risk of mortality by pathogen and a survival analysis with a Cox regression model was used to analyze time to return to a healthy clinical status by pathogen. Rota- virus was the most prevalent at 75.5% (209/277), followed by K99+ E. coli at 42.8% (115/269), C. parvum at 28.0% (65/232), coronavirus at 10.1% (28/277), and Salmonella had the smallest prevalence at 3.7%(10/269). Risk of mortality was significantly higher for calves infectedwith E. coli and Salmonella with relative risks of 4.32 (95%CI: 1.08, 17.27) and 10.98 (95%CI: 2.39, 50.53) respectively (P = 0.038 P =0.002). The pathogens did not, however, have any statistically significanteffect on time to return to a healthy clinical status. Only farm was asignificant predictor of time to return to health (P = 0.0139). The results suggest that rotaviral infections are prevalent and widely distributed across farms; however, mortality is more commonly associated withSalmonella and K99+ E. coli infections. Specific prevention and rapid differentiation from other causes of calf diarrhea are important to reduce risk of mortality in pre-weaned calves with diarrhea.