Stress Adds to Livestock Disease Risk

SASKATOON - Dec 20/07 - SNS -- It appears signs of stress in proteins and other compounds found in blood that can help predict disease susceptibility in livestock say scientists at the University of Saskatchewan's Vaccine and Infectious Disease Organization (VIDO).

In a study in cattle, the researchers found that psychological and physical stressors cause detectable changes in these blood compounds. These "biomarkers" can then be used to predict disease outcomes.

"Our results could someday enable doctors or veterinarians to predict whether a disease will develop and how severe it might be from a body fluid sample such as blood," said principal investigator Palok Aich. "These findings will help improve treatment plans for possible disease outcomes."

It's well known that exposure to viruses or bacteria causes disease in some individuals but not in others. This study helps clarify how the stress level of an individual affects the infection process and disease severity.

The team worked with a stress-linked cattle disease-bovine respiratory disease (BRD), which causes more than half of feedlot deaths. In blood samples, the researchers found a link between stress biomarkers and disease severity.

BRD involves interaction of viral and bacterial infections, making it a perfect model to study the link between stress and disease.

"In BRD and certain human diseases such as influenza, the combination of a bacterial infection after an initial viral infection can be deadly," said Philip Griebel, a VIDO senior scientist and co-investigator. "The better we can recognize the signs suggesting a poor disease outcome, the better we can manage or even prevent an illness."

In the long term, changes in certain biomarkers could also help identify disease-susceptible animals in feedlots or ranches for early intervention and treatment, and help determine handling methods that minimize stress.

Aich says more research is needed to link biomarkers to a specific stressor and to understand which stressors contribute the most to enhanced disease susceptibility.

The team also includes VIDO/InterVac director Andrew Potter, former VIDO director Lorne Babiuk, Gabrielle Schatte of the U of S's Saskatchewan Structural Sciences Centre, and Andrew Ross of the National Research Council of Canada's Plant Biotechnology Institute.