Physiological and Behavioral Aspects of Thermoregulation in Diarrheic Piglets

177 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.The purpose of the research reported and discussed was to examine the physiological and behavioral thermoregulatory responses of normal, diarrheic and pyrogen-injected piglets aged 12 to 72 hours. The first experiment examined the thermal-environmental preference of diarrheic piglets exposed to a thermocline apparatus for 60 minutes. Diarrheic piglets on average preferred a lower ambient temperature than did control piglets. Furthermore, preference for a lower temperature in the thermocline was demonstrated in 48-hour-old piglets than in piglets aged 12, 24 or 72 hours. Rectal temperature rose with increasing age, while the rectal temperature of sucrose-induced diarrheic piglets was lower than that of control piglets. Rectal temperature increase during thermocline exposure was higher in control piglets than in diarrheic piglets. The difference between rectal temperature before thermocline exposure and the temperature preferred by the piglet in the thermocline increased with age. Total body-water determination in piglets by three to four percent. Total body-water content was shown to be lower in sucrose-treated piglets but not in E. coli-infected piglets than in comparable control piglets. Hemoconcentration was observed in diarrheic piglets, while progressive hemodilution occurred with increasing age. Furthermore, packed-cell-volume values fit a sine-wave curve. The second experiment examined the thermal preference of piglets administered a potential fever-inducing bacterial pyrogen. Administration of a pyrogen had no effect on the piglet's preferred environmental temperature. However, 48-hour-old pyrogen-injected piglets behaviorally preferred a higher environmental temperature, while 72-hour-old pyrogen-treated piglets preferred a lower temperature than their control counterparts. Pyrogen administration resulted in an overall rise in rectal temperature five to seven hours post-injection. Bacterial pyrogen did not have an effect on the rectal temperature of 12-or 24-hour-old piglets, but it lowered that of 48-hour-old piglets and increased that of 72-hour-old piglets. Rectal temperature increase during thermocline exposure was higher in control piglets with the exception of 48-hour-old pyrogen-injected piglets. The difference between rectal temperature before thermocline exposure and the preferred environmental temperature was smaller in 48-hour-old pyrogen-infected piglets and larger in 72-hour-old pyrogen-injected piglets than in control animals. The third experiment aimed at determining the resistance of diarrheic piglets to cold stress as measured in thermostability trails. The older the piglet, the more resistant it was to a drop in rectal temperature during a 90-minute exposure to a 6(DEGREES)C environment. Furthermore, the more extensive the weight loss during diarrhea, the less resistant piglets were to a drop in rectal temperature under cold stress. Both the thermal-circulation index and surface temperature following cold exposure decreased with age with the exception of 48-hour-old piglets. A trend towards increased vasoconstriction while a decrease in surface temperature in E. coli-infected and sucrose-treated piglets was demonstrated. Total body-water content of diarrheic piglets was not different but tended to higher than control piglets.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD