What is the effect of stress on animal immune response?

The impact of stress on an animal's immune response is significant and well-documented in veterinary and animal sciences. When an animal experiences stress, whether due to environmental factors, social interactions, or physiological changes, it triggers a cascade of physiological responses primarily mediated by the hypothalamus-pituitary-adrenal (HPA) axis. This leads to the secretion of stress hormones, such as cortisol, which play a critical role in the body's stress response.

The correct understanding of stress's effect on immune function is that it can weaken the immune response. Under stress conditions, glucocorticoids like cortisol can suppress the activity of various immune cells, including lymphocytes, which are crucial for the adaptive immune system. This suppression affects the ability of the animal to produce an adequate immune response to pathogens, increasing its susceptibility to infections and diseases.

Conversely, while moderate stress may sometimes invoke responses that could seem protective, chronic stress overwhelmingly leads to immunosuppression and increased vulnerability to illness. Therefore, recognizing that stress can weaken immunity is essential for managing animal health and welfare effectively.