Lyte picture

Mark Lyte, Ph.D., M.S., MT(ASCP)

By Rick Sibbel, D.V.M.

Merck Animal Health was pleased to co-sponsor the 2014 BRD Symposium, and continues with its series on sharing some of the latest research findings and management techniques from this meeting.

BRD flourishes in stressed cattle, and we know that such cattle produce numerous stress-related neurochemicals. The general belief has been that neurochemicals are exclusive to the animal kingdom and any role in creating infection is confined to the host animal.

At the symposium, Mark Lyte, Ph.D., M.S., MT(ASCP), Texas Tech University Health Sciences Center, Abilene, TX, explained that today we know that many infectious bacteria species not only recognize stress hormones, but also synthesize the same neurochemicals as the host animal. As such, these infectious bacteria are capable of responding to stress-related neurochemical and initiating disease. This ability is known as microbial endocrinology, and provides us with another mechanism to examine how stress influences the animal’s health and disease susceptibility.

He pointed out that we have more to learn about the cattle lung’s environment following a stress event, but due to the rich blood supply and abundant noradrenergic nerve innervation, substantial neurochemical levels are likely present. Consequently, elevated catecholamine concentrations, such as norepinephrine, within the stressed lung would be available to interact with any bacterial pathogens present.

The results of studies suggest this not only enhances pathogen growth and virulence but also increases the rate of gene transfer and evolution. This allows pathogens to adapt to new environments and contribute to disease development.

The microbial endocrinology-based interactions underscore the ability of stress to influence animal health and disease risks. It would be worth investigating its role in bovine lung infections, such as those related to BRD.

You can get more information on this research or order a copy of the 2014 BRD proceedings at

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