|Kehrli Jr, Marcus|
Submitted to: Advances in Veterinary Science and Comparative Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1998
Publication Date: N/A
Citation: Interpretive Summary: This paper summarized the reported effects of stress on how white blood cells (leukocytes) move through the body to carry out their important task of fighting infectious disease. The effects of stress on how an animal responds to vaccination was also reviewed with particular emphasis on the stress on the immune system when animals give birth. Infectious diseases such as mastitis, diarrhea, and pneumonia are reported on all farms and millions of dollars are spent by farmers in vaccinating their livestock to protect their animals from disease. Some of the value of these vaccines is lost when stressed animals are vaccinated. The benefits of this paper include the recommendation to avoid vaccination of animals with stressed immune systems. This research may eventually reduce antibiotic usage on farms by farmers implementing more effective vaccination protocols for their livestock herds.
Technical Abstract: Stress in livestock can be broadly defined as situations in which normal homeostatic conditions of an animal are disturbed or threatened. This disturbed state can be triggered by various environmental factors to which an animal must respond physiologically to maintain equilibrium with the environment. Release of ACTH which induces synthesis and secretion of glucocorticoids is one response to stress. Recent studies of the effects of glucocorticoids on the immune system of cattle have identified alterations in leukocyte adhesion molecule expression that affect the normal trafficking pattern of neutrophils by causing the shedding of L-selectin. In addition, circulating gd T-cell numbers decline in response to glucocorticoid administration. Additional microbicidal functions of neutrophils are also suppressed by glucocorticoids, as well as the ability of cultured mixed populations of lymphocytes to produce interferon-g. Glucocorticoid administration will also suppress antigen specific immune responses to vaccines. Virtually identical changes in leukocyte trafficking patterns, cytokine and immunoglobulin secretion, and adhesion molecule expression on leukocytes have been reported in periparturient cows. These recognized compromises induced by glucocorticoids and parturient stresses on the immune system should be considered when planning vaccination protocols for management of herd health.