Effects of short-term restraint stress on leukocyte counts, lymphocyte proliferation and lysis of erythrocytes in gilts.

The effects of short-term restraint stress on leukocyte counts, lymphocyte proliferation and lysis of erythrocytes were studied in six gilts. A catheter was inserted into the jugular vein and two blood samples were collected before the onset of stress. Thereafter a hog snare was applied and blood samples were collected at 0.5, 2, and 3.5 min after the start of snaring. Neither the total WBC number, nor the total number of lymphocytes, or the total number of polymorphonuclear leukocytes changed significantly throughout the study. This was also true for the degree of intravasal lysis of erythrocytes. In whole blood cultures stimulated with pokeweed mitogen, an increase (P < 0.05) in the lymphocyte proliferation was recorded in samples collected 3.5 min after the start of restraint. In the mononuclear cell cultures, no significant changes were found in lymphocyte proliferation of blood collected 3.5 min after the start of restraint. Taken together, the short-term stress during blood sampling may affect the cell-mediated immunity but not the leukocyte count nor lysis of erythrocytes in pigs.