In modern intensive livestock production, pigs are easily threatened by different types of inflammation. Immunological stress is a comprehensive process involving immunological, neurological, and endocrinological responses . The reciprocal “subjugation” of the brain and the immune system via cytokines and stress hormones is now well demonstrated [5, 6]. The resulting balance has more recently been demonstrated at the level of blood cell transcriptome , with chronic stress increasing the expression of genes regulated by inflammatory mediators and decreasing those regulated by glucocorticoid hormones . This approach has been used to evaluate the negative consequences of adverse environmental conditions, mostly in humans but also in farm animals (horses ). More recently, individual differences have also been described as related to personality dimensions in humans . However the relationships with individual variations of HPA axis activity, including genetic factors, is still unexplored.