New research from the Royal Veterinary College (RVC) has revealed that nearly one-third of calves in the UK experience bovine respiratory disease and subclinical pneumonia.
The research combined thoracic ultrasounds, alongside the measurement of clinical signs.
RVC said these findings will support veterinary professionals in identifying the optimal techniques to precisely diagnose the condition, supporting bovine welfare.
According to Ruminant Health and Welfare, (RH&W) approximately 1.4 million dairy calves are born in the UK each year, yet bovine respiratory disease is one of the leading causes of disease in pre-weaned calves, and is the main reason for antibiotic use in this population.
However the RVC said diagnosis of the condition is challenging, and has traditionally involved the assessment of clinical signs using scoring methods such as the Wisconsin Respiratory Score, which identifies disease based on visible signs.
More precise techniques for the diagnosis of disease are available, such as thoracic ultrasound, which can help to diagnose the condition with greater precision.
The study is the first of its kind to explore the frequency of bovine respiratory disease using thoracic ultrasound in a large subset of English dairy herds.
Researchers measured the occurrence of bovine respiratory disease in 476 calves born on 16 dairy farms located in southwest England.
Researchers performed a total of 3,344 weekly exams from birth until weaning (approximately eight weeks of age), measuring the respiratory health of calves using both ultrasound and scoring techniques.
The research revealed that the peak prevalence of lung consolidation, where air in the lungs is replaced by a solid, fluid, or other material, occurred at eight weeks of age.
The research also found that subclinical pneumonia, the presence of lung consolidation without outward clinical signs, was common. At any week of age, up to 28.7% of calves were diagnosed with subclinical pneumonia.
These findings demonstrate that subclinical pneumonia was common in the UK population of dairy-born calves, but diagnosis could easily be missed if stakeholders only observed clinical signs.
Clinical respiratory scoring will not identify all cases of bovine respiratory disease and thoracic ultrasound is an essential diagnostic technique which should be implemented by vets in clinical practice to support cattle welfare.
George Lindley, PhD student at the RVC and lead author, said: “The results of this study demonstrate that bovine respiratory disease, including lung consolidation identified via thoracic ultrasound, is common in pre-weaned calves born on UK dairy farms.
“Whilst the disease has negative welfare consequences, affecting growth, survivability, and future productivity, our research suggests that a significant proportion of calves born on UK dairy farms may remain undiagnosed when assessed by clinical signs only,” he added.
