Changes in blood constituents accompanying exercise in polo horses.

There have been several studies of biochemical changes in horses doing intense exercise such as Thoroughbred and Standardbred racehorses and in horses performing exercise over a long period of time such as endurance horses and three-day eventing horses, but we are not aware of studies with polo horses. Blood samples were taken from 18 polo horses at rest, immediately after playing 2 chukkers of indoor polo, and after a 15 minute rest period. Each horse was studied at 2 different games. The blood samples were analyzed for lactic acid, protein, sodium, potassium, chloride, calcium, phosphorus, HCO-3, PCO2, hemoglobin, packed cell volume, and pH. Samples taken immediately after playing polo had significant increases in lactic acid, protein, sodium, hemoglobin, packed cell volume, and pH, and significant decreases in chloride, calcium, PCO2, and HCO-3. Pulse and respiration were significantly increased. After a 15 minute rest period, there was a significant decrease in potassium. The HCO-3 was lower immediately after playing, but was above the resting value after 15 minutes. It was concluded that the changes after exercise are similar in some aspects to those reported for horses performing intense exercise such as racehorses, and in some aspects to those reported for horses performing prolonged exercise such as three-day event horses and endurance horses. Horses playing indoor polo develop a high plasma lactic acid, but with alkalemia, and could be used as a model to study this condition.