Why Calf Cough is an Unreliable Early Warning Sign for Respiratory Diseases in Calves
Research conducted in the US suggests that relying on calf cough to diagnose respiratory diseases in calves is not an effective early warning tool. Waiting for clinical symptoms to appear can result in undetected and untreated cases of pneumonia, which can cause significant damage to the respiratory system of calves and negatively impact their production potential.
Veterinary epidemiologist Terri Ollivett analyzed ultrasound scanning data collected over three years from a herd where subclinical pneumonia was a significant problem. The calves were scanned every week between 10-35 days of age. They were given a lung score based on consolidation levels, with 0 indicating a completely normal lung and 5 indicating the most severe cases of bacterial pneumonia. Of the 117 calves that received a score of 5, only 18% displayed evidence of a physical cough. Therefore, if a calf does not cough, it should not be used to rule out severely consolidated lungs.
To address this issue, Ollivett has pioneered an approach called WeanClean, which involves using lung ultrasonography to check calves for lung lesions well before clinical symptoms are likely to be displayed. This approach involves carrying out ultrasounds at four strategic points: at the start of weaning, at the start of treatment, 7-10 days after treatment, and at 12×7 scans starting at seven days old. The goal is to measure lung disease at weaning and administer treatment if needed so that producers can wean their animals with clean and healthy lungs.
It is important to note that subclinical pneumonia is likely to be present in 50-80% of cases for seven to 14 days before clinical symptoms are displayed. Therefore, early detection and treatment are essential for minimizing damage to the respiratory system and maximizing the production potential of calves entering the herd. This research highlights the importance of using ultrasound scanning as an effective tool for the early detection and treatment of respiratory diseases in calves rather than relying solely on calf cough.