CHANGES IN BLOOD-GASES AND ELECTROLYTES OF HORSES GIVEN VARYING DOSESOF SODIUM-BICARBONATE

Eight Quarter Horse mares, ranging in age from 5-15 years were used in a 4-week Latin-Square design experiment in which pairs of horses were given 0, 333, 666, or 1000 mg/Kg body weight of sodium bicarbonate (N aHCO3) via nasogastric tube once weekly. Blood samples were drawn imme diately before nasogastric intubation and then in one-hour increments for eight hours and once again at twenty-six hours after intubation. B lood pH, HCO3-,PCO2, and PO2 and the serum electrolytes, Na+, K+, Cl- and Ca++ were determined. Each treatment with NaHCO3 produced an incre ase (p < .01)in pH and HCO3- within two hours post-intubation, and an increase (p < .01) in PCO2 within four hours. Peak mean values for pH, HCO3-, and PCO2 were reached between four and six hours after intubat ion for all NaHCO3 treatments and remained elevated through eight hour s after intubation. Serum Na+ was elevated (p < .01) and serum K+ and Cl- were reduced (p < .01) following NaHCO3 administration. All blood gas and serum electrolyte changes were found to return to near baselin e levels by 26 hours after intubation. The fact that peak mean pH and HCO3- values were not reached until up to four hours after NaHCO3 admi nistration is important to consider when developing regulations for pr e-race blood gas testing.