Clinical respiratory disease in young cattle has long been a major cause of morbidity and mortality in the dairy, beef, and veal industries.
Prompt and appropriate treatment of respiratory problems is therefore routine practice on many farms. However, we all know that treatment success can be variable. The problems rarely disappear completely and often recur sooner or later, particularly during periods of stress or increased infection pressure. In addition, subclinical or “hidden” cases ensure that pneumonia remains a persistent challenge.
Detecting Pneumonia Remains Challenging
In practice, the diagnosis of pneumonia in calves starts with a clinical examination. During the examination, attention is paid to signs such as coughing, nasal discharge, increased respiratory rate, fever, reduced appetite, and general condition. Clinical scoring systems, such as the Wisconsin Respiratory Scoring Chart, can be useful in this process.
The main limitation of these scoring systems is that they rely on visible clinical signs, which means that subclinical cases may go undetected (potentially up to 30%). Additional diagnostic investigations are generally only initiated when the clinical findings indicate the need to identify the underlying etiological agents.
For the diagnosis of lower respiratory tract infections, a non-endoscopic bronchoalveolar lavage (nBAL) is frequently performed. This procedure provides information on the presence of inflammatory cells and pathogens such as bacteria, viruses, and fungi.
A less invasive but also valuable option is the collection of deep nasopharyngeal swabs (DNPS) for microbiological examination. Studies have shown that deep nasopharyngeal swabs and bronchoalveolar lavage samples have a similar ability to detect the main bacterial pathogens, including Mannheimia haemolytica, Pasteurella multocida, and Mycoplasma bovis.
The situation is somewhat different for viral infections. Viral pathogens such as Bovine Respiratory Syncytial Virus (BRSV) and Parainfluenza-3 Virus (PI3) can be detected more readily using bronchoalveolar lavage samples, whereas Bovine Coronavirus (BCoV) is more easily detected in deep nasopharyngeal swabs.
As it is often unclear which pathogens are primarily involved, a combination of both DNPS and nBAL samples appears relevant to increase the sensitivity of the diagnostic approach.
Lung Ultrasonography and Its Added Value
The scientific literature increasingly recommends the use of lung ultrasonography as part of the diagnostic work-up.
Ultrasonography enables the visualization of abnormalities such as lung consolidation, pleural changes, and abscesses, even when clinical signs are minimal or absent. As a result, it provides a more complete picture of both the cause and the severity and extent of lung damage.
Moreover, lung ultrasonography can be performed without sedation and provides immediate results. It therefore represents a valuable complement to nBAL and DNPS, both for diagnosis and for monitoring disease progression and treatment response.
Practical Conclusion
Pneumonia in calves remains a disease with significant animal welfare and economic consequences.
For an accurate etiological diagnosis of pneumonia, bronchoalveolar lavage and/or deep nasopharyngeal swabbing are often indispensable. However, lung ultrasonography also deserves a place among these diagnostic tools, as it allows the detection of early, subclinical lung lesions before obvious clinical signs become apparent.
If you would like more information about respiratory diagnostics or lung ultrasonography, please do not hesitate to contact us via [email protected].
Chris Cornelis
Technical Support Veterinarian Ruminants
