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 i ts 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 an imals were used as controls. On both sampling days, jugular blood samp les were collected from all pigs via catheters. Antibody titers agains t 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 S RIF immunization had no influence (P > 0.05) on any of the measured va riables, but a significant interaction(P < 0.01) between stress and th e time of sampling was observed. At 2 min, increases (P < 0.05) in hem atocrit (26%), hemoglobin (18%) and total protein (10%) were observed in stressed animals. Values returned to prestressed levels within 30 m in 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 inductio n of stress. An 80% increase in glucose concentration was seen at 10 m in post-stress but values returned to baseline levels after 4 h. In co nclusion, the acute stress of snare restraint produced numerous change s in blood variables as early as 2 min post-stress, regardless of gend er and SRIF immunization status. Therefore, special attention should b e given to the methodology of blood sampling and to the level of stres s imposed on the animals during the blood sampling before drawing any conclusion based on hematological or biochemical values.