One of the most challenging aspects of controlling bovine respiratory disease syndrome (BRDS) is the difficulty in diagnosing the disease, particularly in its early stages when treatment is most effective. Multiple pathogens and environmental interactions result in a wide range of clinical signs. And some of the classic signs of BRD such as depression, fever or reduced appetite can result from conditions unrelated to BRD.
When researchers examine cattle lungs at packing plants, they typically find a high percentage of lesions in cattle that were never pulled or treated for BRD, and lungs with no lesions from cattle that were diagnosed and treated. The new “Whisper” electronic stethoscope system aims to change that.
During the recent BRDS symposium in Denver, Nebraska veterinarian Tom Noffsinger described the system, validation research and its potential application in feedyards and dairies.
Noffsinger notes that in many feedyards, a rectal thermometer is the only objective diagnostic tool used to evaluate cattle for BRD. Most diagnoses rely on subjective observations, and even rectal temperature is not entirely reliable for diagnosing BRD. A conventional stethoscope can significantly improve chute-side diagnostics. Research from Noffsinger’s practice group, Professional Animal Consultants, showed a 34 percent reduction in mortality rates in pulled cattle that were auscultated (examined with a stethoscope, compared with non- auscultated respiratory pulls. The data set included more than 500,000 cattle. But even in trained hands, identifying and interpreting specific lung sounds in cattle can be challenging.
The Whisper electronic stethoscope system includes software that interprets lung sounds and measures five different levels of lung health. Researchers spent several years developing the system and validating the scoring system with input from expert veterinarian auscultators.
The Whisper lung scores indicate severity, duration and progression of disease, Noffsinger says. Caregivers can use the information to make objective treatment decisions and evaluate outcomes, potentially leading to reductions in BRD-related losses and more judicious use of antimicrobials.
In a study of over 3,000 cattle, researchers found a 6 percent correlation between body temperature and case-fatality rate, with a confidence interval of 2.5 to 9.5 percent. In contrast, the correlation between the Whisper lung score and case-fatality rate was 79.8 percent with a confidence interval of 78.5 to 81.1 percent.
In these trials, the number of false negatives with fever as a diagnostic test predictor (i.e. those that died and did not have a fever) was 608 head. The number of false negatives with Whisper lung score of “1”as a diagnostic test predictor was 210 head, a reduction of 65 percent. The number of false negatives with a combined fever and Whisper lung score was 102 head 506 head or 83 percent less than fever alone as diagnostic test predictor and 108 less head than Whisper lung score alone as a predictor of fatality.
When used in a production animal setting, Noffsinger says, Whisper is neither perfect nor infallible. However, the utilization of auscultation via Whisper has resulted in better case definition, improved risk assessment, stratification of cattle by lung score, and targeted antibiotic treatments. The new audio technology, he says, will change the way you “see BRD.”
The Whisper Electronic Stethoscope was developed by Geissler Corporation and will be marketed by Micro Beef Technologies.