Effects of oral potassium supplementation on acid-base status and plasma ion concentrations of horses during endurance exercise.

The study aimed to compare the effects of a potassium-free, sodium-rich electrolyte supplement with a potassium-rich supplement on aspects like acid-base balance and blood ion levels in horses during an 80-kilometer endurance ride. The results showed changes in various blood parameters, but increases in blood potassium and hydrogen ion levels were mild and unlikely to contribute to muscle fatigue or hyperexcitability in horses.

Methods

• The study involved 46 healthy horses and they were monitored during an 80-kilometer endurance ride.
• They were given either a potassium-free, sodium-rich electrolyte mixture (EM-K) or a commercial potassium-rich mixture (EM+K).
• Blood samples were taken before the ride; at 21, 37, 56, and 80 kilometer inspection points; and during the 30-minute recovery period after the ride.
• The consumed electrolytes were also recorded during this period.
• The blood samples were analyzed for several parameters including pH, PvCO2, and Hct (hematocrit), while the plasma was analyzed for concentrations of sodium, potassium, chloride, calcium, magnesium, lactate, albumin, phosphate, and total protein.
• From these, the researchers calculated the plasma concentrations of hydrogen ions and bicarbonate, the strong ion difference (SID), and osmolarity.

Results

• Out of 46 horses, 34 (17 from each group) completed the endurance ride.
• The horses given the potassium-free supplement (EM-K) consumed 33 grams less potassium and 36 grams more sodium compared to the horses on the potassium-rich supplement (EM+K).
• All horses showed an increase in plasma osmolarity; hydrogen, sodium, potassium, magnesium, phosphate, lactate, total protein, and albumin concentrations; and PvCO2 and hematocrit as the ride progressed.
• However, the concentrations of bicarbonate, calcium, and chloride in plasma decreased during the ride.
• Significantly, the horses in the EM-K group had lower plasma hydrogen concentration compared to the EM+K group.
• Plasma potassium concentrations at the 80-kilometer point and during recovery were also significantly lower in the EM-K group.

Conclusions

• The increase in plasma hydrogen and potassium concentrations during the endurance ride was mild.
• These changes probably do not contribute significantly to signs of muscle fatigue and hyperactivity in horses.
• This suggests that potassium intake might not greatly influence these factors during endurance exercises in horses.