The difference between Acidosis and Alkalosis

Acidosis and Alkalosis

A horse’s blood has a pH of 7.4 – 7.45, making it very slightly alkaline. It is very important that a horse’s blood pH is kept within these levels for the horse to function correctly. Fortunately, a horse’s system is very good at maintaining this, but to do so it requires the right electrolytes and fluids to be available.

The pH Scale

Alkalosis
Hypochloraemic alkalosis occurs in horses exercising at moderate intensity over a longer period of time, that is, half and hour or more, and therefore encountering overall heavy sweat loss. A large quantity of sweat loss equals a large level of electrolyte loss, particularly chloride.  This results in the blood becoming more alkaline.  Alkalosis results in poor performance, blowing or thick windedness, nervousness and increased bicarbonate levels in the blood. 

Acidosis
Horses exercising at a very high intensity for a shorter period of time will lose less sweat, but will produce excess lactic acid in their muscles which can lead to acidosis. This lactic acid is transferred to the blood causing it to become more acidic. Acidosis results in muscle fatigue and soreness, lack of stamina and can lead to ‘tying up’.

Endurance horses are heavy sweaters and can lose up to 60 litres of sweat in a hard race.

Electrolytes play a vital role in the horse’s body function and all are lost in the horse’s cooling processes in differing amounts depending on the activity being undertaken. This is why it is necessary to supplement with a complete electrolyte that contains the right balance to meet the horse’s requirements.

Recovery

After a horse finishes a period of intense exercise, its heart rate is still elevated and heat still needs to be expelled. Any lactic acid in the system needs to be recycled and toxins and free radicals excreted. Lactic acid is produced when the body burns energy over the amount generated aerobically (with oxygen). This is termed an oxygen debt and has to be paid back at some point. It is paid back during the recovery phase by converting the lactic acid back to pyruvate, a process that requires oxygen. In this situation, the horse will continue to breathe heavily even after finishing the exercise. This process is termed ‘repaying the oxygen debt.’ The heart rate will remain elevated as the oxygen debt is repaid and the horse will continue to sweat until it has regained control over its elevated temperature.

Whilst and after the oxygen debt has been repaid and the body heat dissipates, the kidneys filter the blood and remove toxic metabolites. The process of remodelling and repairing any damage commences and the replenishment of energy reserves begins.

Any nutrients lost in this process, including vitamins, water and electrolytes, must be replaced through the diet or supplementation.

Reducing Recovery Time

B vitamins play an important role in the recovery of horses that have had a period of intense exercise, or suffered from stress or illness. B vitamins aid in building appetite as well as providing muscle and blood-repairing properties.

Vitamin E and selenium are powerful antioxidants that assist horses which are prone to tying up by neutralising the damaging free radicals that are naturally produced during hard exercise. Lactic acid build-up and the formation of free radicals are thought to contribute to tying up. This can be countered with the aid of buffers and mild diuretics. Citrate buffers such as those in Neutradex are a natural bicarbonate precursor. Adequate levels of these stored in the horse’s system enable it to very effectively neutralise lactic acid before it can cause damage to the muscles.

To help you pick the right electrolyte supplement for your horse, check out our article Choose the Right Electrolytes for Your Horse (https://au.virbac.com/health-care/horse-electrolytes/choose-the-right-electrolytes).