Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Science


The first study was conducted to compare catecholamine concentrations in nervous tissue of stress-susceptible (SS) and stress-resistant (SR) pigs that were physically stressed. Ten pigs were included in each group on the basis of halothane screening, blood typing, and serum creatine phosphokinase activity at 6 weeks of age. The nervous tissue analyzed included the substantia nigra (SN) and the caudate nucleus (CN). These tissues were taken from pigs as soon as possible after death, frozen in liquid nitrogen, and later radioenzymatically assayed for dopamine, norepinephrine, and epinephrine concentrations;The SS pigs exhibited significantly greater (p 0.001) creatine phosphokinase (CPK) concentrations than did the SR pigs before and after physical stress. Concentrations of dopamine, norepinephrine, and epinephrine in the CN of the SS pigs were significantly lower (P 0.05) than those in the CN of the SR pigs. Similarly, the SN of SS pigs has lower dopamine, norepinephrine, and epinephrine concentrations than did the SN of SR pigs. The catecholamine deficiencies observed in the porcine stress syndrome (PSS) seem to have similarities with certain human extrapyramidal diseases;A second study was conducted to compare pulmonary and hematologic functions of SS and SR pigs. Several significant differences in hematologic values were found between the two types of pigs. All SS pigs had significantly less hemoglobin than the SR pigs. All SS pigs had significantly greater values for arterial pCO(,2), base excess, HCO(,3)('-), and total CO(,2) than did SR pigs. The SS pig also had significantly less venous base excess but greater HCO(,3)('-) and total CO(,2) than did the SR pig;Type differences in pulmonary function values also were observed. The SS pig had significantly less pulmonary resistance than did the SR pigs. Morever, the SS pigs have significantly greater physiologic dead space and a significantly lower ventilation perfusion ratio than did the SR pigs. The pulmonary and hematologic differences between SS and SR pigs provide some explanation for some of the clinical signs seen in the porcine stress syndrome and suggest that the pathophysiologic mechanisms of this syndrome include abnormalities of the respiratory system as well as those of the muscular and nervous systems.



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John W. Hallberg



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93 pages