Subclinical characteristics of the wasting pig syndrome

The plasma concentrations of cortisol and corticosteroid-binding globulin and the adrenal synthesis capacity of cortisol were analysed in 10-week-old healthy and age-matched wasting or unthrifty pigs. Crypt cell multiplication, villus height and intestinal mucosal alkaline phosphatase (ALP) activity were also investigated. Furthermore, the effect of amperozide, a psychotropic drug with specific effects on emotional behaviour, was analysed for its effect on plasma ALP activity and villus height. Although the wasting pigs exhibited an increased cortisol synthesis capacity, there was a decreased plasma concentration of cortisol in these pigs. Furthermore, the plasma cortisol binding capacity was found to be significantly lowered in wasting pigs. There was also a reduced crypt cell proliferation, a reduced villus height and a decreased ALP activity in the ileal mucosa. Treatment with amperozide resulted in a normalisation of plasma ALP activity in unthrifty pigs, indicating a stimulation of body growth. The results indicate that the growth depression of wasting pigs is most probably a chronic stress syndrome caused by the inability of these animals to cope with the events following weaning and mixing.