Natalia da Silva

A mixed treatment comparison meta-analysis of antibiotic treatments for bovine respiratory disease

In this publication we use mixed treatment comparison meta-analysis to compare the efficacy of antibiotic treatments for bovine respiratory disease in beef cattle. Studies were eligible for the meta-analysis if they were publically available and reported the assessment of antibiotic protocols registered for use in the United States (US) for bovine respiratory disease (BRD) in beef cattle and were conducted in North America. Three electronic databases, the proceedings of two bovine specific conferences, pharmaceutical company web sites and the US Food and Drug Administration website were searched to identify relevant trials. The network of evidence used in the analysis contained 194 trial arms from 93 trials. Of the 93 trials there were 8 with three arms. The network of evidence contained information for 12 antibiotics. The output from the analysis provided information about the risk ratio comparing all possible treatments for BRD including comparisons based only on indirect data. The output also included a relative ranking of the treatments and estimates of the probability that an antibiotic protocol was the worst treatment option.

Pain and sickness behavior associated with corneal lesions in dairy calves

Infectious bovine keratoconjunctivitis (IBK) is a common corneal disease of calves that adversely affects animal welfare by causing pain and weight loss. Identifying behavioral indicators of pain and sickness in calves with IBK is necessary for designing studies that aim to identify effective means of pain mitigation. Consistent with principles of the 3Rs for animal use in research, data from a randomized blinded challenge study was used to identify and describe variation of behaviors that could serve as reliable indicators of pain and sickness in calves with corneal injuries. Behavioral observations were collected from 29 Holstein calves 8 to 12 weeks of age randomly allocated to one of three treatments: (1) corneal scarification only, (2) corneal scarification with inoculation with Moraxella bovoculi and (3) corneal scarification with inoculation with Moraxella bovis. Behavior was continuously observed between time 1230 - 1730 h on day -1 (baseline time period) and day 0 (scarification time period). Corneal scarification and inoculation occurred between 0800 - 1000 h on day 0. Frequency of head-directed behaviors (head shaking, head rubbing, head scratching) and durations of head rubbing, feeding, standing with head lifted, lying with head lifted and sleeping were compared between study days and groups. Following scarification, the frequency of head-directed behavior significantly increased (p = 0.0001), as did duration of head rubbing (p=0.02). There was no significant effect of trial, trial day, treatment or treatment-day interaction on other behaviors studied. Our study demonstrated that head-directed behavior, such as head shaking, rubbing and scratching, was associated with scarification of eyes using an IBK challenge model, but sickness behavior was not observed.