Study makes BRD ultrasound diagnosis plea

Many cases of a common disease in calves could go undiagnosed if veterinary assessments are based solely on clinical signs, a new study has warned.

RVC researchers said they hope the findings will encourage greater interest in the use of thoracic ultrasound (TUS) techniques alongside established bovine respiratory disease (BRD) scoring systems to help protect herd welfare.

The plea is based on the analysis of hundreds of calves in what the study’s authors said is the first of its kind to examine BVD frequency in English herds using the two methods.

‘Engagement’

Lead author George Lindley said: “Thoracic ultrasound is fast and relatively easy to perform, and we hope that more widespread engagement will help to improve youngstock health and performance.”

A total of 476 calves across 16 farms in south-west England were examined during the study, the findings of which have now been published in the Animals journal.

More than 3,300 separate examinations were conducted on a weekly basis from when the calves were born until they reached the point of weaning, usually at around eight weeks old.

The tests used both TUS and respiratory scoring techniques that are based on the assessment of clinical signs including coughing, nasal or ocular discharge, temperature and ear position.

Lung consolidation

The study, which was funded by the Barham Benevolent Foundation, found that cases of lung consolidation, where air was replaced by a solid, fluid or other material within the lungs, peaked at 29% in week eight.

But a similar proportion (28.7%) were also diagnosed with subclinical pneumonia, where lung consolidation occurs without clinical signs, in any week.

The paper acknowledged that the scoring systems used in the examinations were designed to be used more frequently than they were within the study period and may have contributed to the proportion of consolidation cases that were detected without a positive score, despite the volume of subclinical pneumonia incidents recorded being lower than other published studies.

‘Optimisation’

However, the authors also urged vets, farmers and stakeholders to “consider the integrated use of respiratory scoring and TUS for the optimisation of respiratory health”.

Around 1.4 million dairy calves are estimated to be born in the UK every year, and BRD is believed to be the main driver of antibiotic use within the population.

Dr Lindley, a European veterinary specialist in bovine health management and PhD student, said the findings showed the disease was “common” on UK dairy farms, despite limitations in the sampling of participating farms and the loss of some calves from follow-up analysis.

But he added: “While 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.”