Effect of sodium bicarbonate administration on blood constituents of horses.

OBJECTIVE

To describe changes in blood constituents of horses after oral and i.v. administration of sodium bicarbonate (NaHCO3), and to determine whether the changes are dose dependent.

ANIMALS

6 adult Standardbred 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 changes in blood constituents were measured. Access to food and water was denied during the experiment. Blood samples were collected immediately before treatment and at hourly intervals for 12 hours after treatment, and were analyzed for blood gas tensions; serum osmolality; serum sodium, potassium, chloride, and creatinine concentrations; PCV; and total solids concentration in plasma.

RESULTS

All NaHCO3 treatments induced significant (P < 0.05) metabolic alkalosis, hypernatremia, hypokalemia, 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 least 12 hours, whereas hypercapnia lasted 2 hours in mares given the 250-mg dose orally or i.v. (P < 0.05). A tendency for reduction in PCV, proteins in plasma concentration, and serum concentration of chloride was observed 1 hour after i.v. administered doses of NaHCO3.

CONCLUSIONS

Oral or i.v. administration of NaHCO3 (> or = 250 mg/kg) to resting horses without ad libitum access to water induces significant and persistent acid-base and electrolyte changes.