EFFECT OF SODIUM-BICARBONATE ADMINISTRATION ON BLOOD-CONSTITUENTS OF HORSES

Objective-To describe changes in blood constituents of horses after or al and IV administration of sodium bicarbonate (NaHCO3), and to determ ine whether the changes are dose dependent. Animals-6 adult Standardbr ed mares. Procedure-3 oral doses (1,500, 1,000, and 250 mg/kg of body weight) or 1 intravenous dose (250 mg/kg, 5% solution) of NaHCO3 in 3 L of water, or water (3 L orally), were given to the mares; then chang es in blood constituents were measured. Access to food and water was d enied during the experiment. Blood samples were collected immediately before treatment and al hourly intervals for 12 hours after treatment, and were analyzed for blood gas tensions, serum osmolality; serum sod ium, potassium, chloride, and creatinine concentrations; PCV; and tota l solids concentration in plasma. Results-All NaHCO3 treatments induce d significant (P < 0.05] metabolic alkalosis, hypernatremia, hypokalem ia, and hyperosmolality for at least 8 hours. in mares given the 1,500 - and 1,000-mg doses of NaHCO3 orally, hypercapnia persisted for at le ast 12 hours, whereas hypercapnia lasted 2 hours in mares given the 25 0-mg dose orally or IV (P < 0.05). A tendency for reduction in PCV, pr oteins in plasma concentration, and serum concentration of chloride wa s observed 1 hour after IV administered doses of NaHCO3. Conclusions-O ral or IV administration of NaHCO3 (greater than or equal to 250 mg/kg ) to resting horses without ad libitum access to water induces signifi cant and persistent acid-base and electrolyte changes.