HEMATOLOGICAL AND BIOCHEMICAL-CHANGES FOLLOWING AN ACUTE STRESS IN CONTROL AND SOMATOSTATIN-IMMUNIZED PIGS

Sixteen Yorkshire pigs (49 +/- 2 kg BW) were used. Half (4M, 4F) were immunized against somatostatin (SRIF-IMM) and the other half against its conjugated protein (BSA-IMM) at 10, 12 and 14 wk of age. At the age of 19 wk, half the animals were subjected to 5 min of snare restraint, followed 2 d later by the other half; on both days the unstressed animals were used as controls. On both sampling days, jugular blood samples were collected from all pigs via catheters. Antibody titers against SRIF at 1:150 serum dilution were 0.5 +/- 0.1% and 54.5 +/- 4.9% in BSA-IMM and SRIF-IMM pigs, respectively. Gender, day of sampling and SRIF immunization had no influence (P > 0.05) on any of the measured variables, but a significant interaction(P < 0.01) between stress and the time of sampling was observed. At 2 min, increases (P < 0.05) in hematocrit (26%), hemoglobin (18%) and total protein (10%) were observed in stressed animals. Values returned to prestressed levels within 30 min after cessation of stress. The total leukocyte count increased (P < 0.05) by 10-20% in all samples following stress, while the lymphocyte count decreased by 15% and the neutrophil count increased by 36% over time. Maximal increases in serum concentrations of Na (3%), K (23%), Ca (11%), P (12%) and cholesterol (8%) were seen as soon as 2 min post-stress while FFA values decreased (25%) 20 min following the induction of stress. An 80% increase in glucose concentration was seen at 10 min post-stress but values returned to baseline levels after 4 h. In conclusion, the acute stress of snare restraint produced numerous changes in blood variables as early as 2 min post-stress, regardless of gender and SRIF immunization status. Therefore, special attention should be given to the methodology of blood sampling and to the level of stress imposed on the animals during the blood sampling before drawing any conclusion based on hematological or biochemical values.