Lung consolidation can recur and persist in dairy calves despite early diagnosis and multiple antibiotic treatments according to research in the Journal of Dairy Science®
Respiratory disease adversely affects preweaned dairy calves in the short and long term, contributing to morbidity and mortality, decreased growth, and loss in milk production. Approximately 12% of calves in the United States are treated for respiratory disease, most commonly presenting as bronchopneumonia. Systemic antibiotic therapy is the most common treatment for calves with this diagnosis. In anarticle appearing in the Journal of Dairy Science, scientists from University of Wisconsin, Madison, and Michigan State University assessed the effects of early antibiotic therapy on preweaned calves diagnosed with respiratory disease using respiratory scoring and portable lung ultrasound.
Researchers examined calves from two herds in southern Wisconsin twice per week from three to five days of age until weaning at approximately fifty-six days. The examination included a clinical respiratory examination, lung ultrasound, fecal score, and heart girth measurement. For diagnosis, a positive case was determined with a combination of a calf’s clinical respiratory score and its lung ultrasound score. “Although our method of diagnosis is not considered a gold standard, it likely represents the closest, most practical way that we have at the moment to characterize consequential lung disease in dairy calves,” said lead author Theresa Ollivett, PhD, Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, USA.
Of the 357 calves enrolled in the study, 289 calves developed respiratory disease. Calves that tested positive for respiratory disease were randomly assigned to receive either an antibiotic labeled to treat respiratory disease or a placebo with an equal amount of saline solution at first detection. “In theory, the earlier in the pathologic process that therapeutic drug levels are achieved within the parenchyma of the lung, the faster bacterial replication and neutrophil infiltration should cease, stifling the progression of lung lesions and hastening the resolution of lung consolidation,” said Ollivett.
The study indicated short-term benefits of early antibiotic therapy after diagnosis via respiratory scoring and lung ultrasound. Overall, however, lung consolidation recurred and persisted to weaning, despite early diagnosis and treatment, and the authors call for more research to address antimicrobial stewardship and treatments in on-farm and research settings.
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