EFFECT OF REPEATED BLOOD-SAMPLING ON PLASMA-CONCENTRATIONS OF CORTISOL AND TESTOSTERONE AND ON LEUKOCYTE NUMBER IN SILVER FOX VIXENS (VULPES-VULPES)

It is of great importance to be able quantitatively to evaluate the st ress to which captive fur animals are subjected to by various forms of management. A range of haematological and hormonal parameters have be en shown to be good indicators of stress. However, blood sampling, whi ch entails the presence of humans and handling of the animals, can its elf be a stressor that influences the results of an experiment. The pr esent study shows that a group of silver foxes (n = 7) that had been r egularly blood sampled (RBS-group) for a year had higher plasma concen trations of cortisol and lower concentrations of testosterone compared with an earlier non-blood-sampled group (NBS-group) (n = 7). The RBS- group also tended to have a lower number of lymphocytes. In addition, during a series of five blood samples taken at 30 min intervals, both groups showed an increase in plasma concentrations of cortisol, wherea s numbers of lymphocytes and eosinophil leucocytes decreased. Plasma t estosterone concentrations decreased after an initial increase. The st udy demonstrated that blood sampling, in both the long and short term, can profoundly affect hormone concentrations and leucocyte numbers.