Developing the Sport Horse: The Importance of Hydration

How does heat and humidity affect the horse’s ability to perform?

In humid conditions, the air is already saturated with moisture. This reduces evaporative cooling, allowing sweat to cling to the hair like a hot blanket, causing a rapid increase in body temperature. Horses that are struggling with overheating will often be “inverted” or be seen to pant. Inversion is when the respiratory rate is higher than the heart rate (over a one-minute count). It can look like the horse is panting.

Once fluid loss (dehydration) has reached five percent of body mass (approximately 20 – 25 litres in your average saddle horse) there is a noticeable reduction in performance. Dehydration levels above five percent cause the athlete to feel ill as organ and brain function are impaired. It is also interesting to note that dehydrated athletes sweat less than normally hydrated horses (as the body tries to conserve any fluids it can). This further reduces the cooling mechanisms of the body, starting up a vicious cycle that can only lead to an overheated and severely dehydrated horse if not corrected early.

How can we improve our athlete management under these circumstances? “An ounce of prevention is worth a pound of cure.”

1. Make a plan - discuss the day’s heat stress index with everyone at the barn so that all team members are aware of the risk and what they need to watch for over the course of the day. Early recognition is key.

2. Teaching horses at home to drink electrolyte solutions or accept syringed electrolyte supplementation is also a good practice. Electrolytes can also be supplemented in the grain rations. Remember that horse sweat is a highly concentrated salt solution - there is approximately 10 grams of electrolytes per litre of sweat. Offer water frequently in between horse show classes, and ensure buckets are topped up when the horse returns to the stall.