Too Hot to Trot?

The glory days of summer are upon us! Schooling, showing, and long trail rides keep us busy

through the week, while competitions, shows, and equine getaways entertain our weekends. As

the days get hotter, the demand for performance continues. We push ourselves and our horses

to the next level to work towards new goals and experiences. Although horses are generally well

adapted to hard work in many climates, the extreme heat of the summer can put our horses in a

hazardous position. What are some of the dangers that heat can cause in a horse? How can we

help keep our horses cool and conditioned for a high summer workload? Where do we draw the

line in order to keep our equine partners safe from high heat hazards?



Preceding the Olympic Games 1996 in Atlanta, a cooperative international research effort

identified key strategies for safe competition in hot and humid conditions.This knowledge was a

major factor that these Olympic Games proceeded successfully with no incidents, unlike previous

events (Barcelona 1992) where several horses collapsed during and after the cross country phase.

Hong Kong 2008 was another milestone in research as the international equestrian community feared 

the extreme humidity of Hong Kong. I was lucky to have been able to take

part in Pre-Olympic Heat and Humidity workshop organized by the FEI in Lausanne and

experienced first hand how meticulously these events were planned and how well the venue

and teams prepared for the conditions in China.

While my dreams and your dreams to make it to the Olympic Games might not come true, the

lessons learned and knowledge gained from our elite athletes are very much applicable to our

daily (horse) life.


So what are the dangers? Overheating and loss of electrolytes will lead to heat exhaustion and

Hypothermia ultimately leading to heat stroke, if we do not intervene and help in time.

The horse’s muscle produce an tremendous amount of heat, this heat is transported via the

bloodstream to the peripheral arteries and increases the skin temperature while sweat glands

are activated and the secreted ration of water and this radiation of heat helps to cool the body

down. About 85% of the heat is dissipated via sweat and another 15% through the respiratory

tract via panting.


Heat stress will lead to heat exhaustion which will lead ultimately to heat stroke!

The symptoms of heat exhaustion are:

Profuse sweating

Muscle weakness

Stumbling

Rapid breathing

And increased body temp over 102 F (38.9 C)

Once the body's compensatory mechanisms are overwhelmed, heat stroke will develop:

The skin will feel hot and dry

Massive rapid panting,

Rapid irregular pulse

Temps above 106 F (42 C)

Delirium

Convulsions

Death


What to do?

How to cool down the horse most efficiently?

Here are the instructions established for Hong Kong 2008:

● The horse should be covered from head to tail in cold water

Both sides continuously for about 30 seconds

You can use buckets or hoses

● After that walk the horse for about 15 seconds

This short period of walking will promote circulation and maintain skin blood flow.

● There is no need to scrape water off the horse at any time during the cooling

procedure - the thin layer of warm water close to the skin will be displaced by more cold

water.

If the horse tolerates it the horse can be hosed down while walking, but don't let horse

stand - we want the blood flow going from the muscles to the skin.

● Again - It is more efficient to NOT SCRAPE, but to keep re-dousing with cold water.

● When do we stop?

● When the rectal temperature is at least below 39C /102 F - and yes when you are done

with the cold water and the horse has cooled down - then you can scrape.

Taking rectal temperature immediately after exercising might be misleading as it tends to lag

behind core and muscle temperatures. it is not uncommon for rectal temps to rise 5 to 10 min

after exercise.

It takes about 10 min of intensive cooling to reduce the body temp by one degree C.

For example many horses finishing the cross country portion may have critically high

temperatures close to 42C (>106 F). So in order to get the body temperature down to normal it

can take 20 to 30 min of intense cooling efforts.

Common mistakes:

● Underestimating the amount of water that needs to be applied!

● Concentrating on avoiding specific areas of the body rather than using the whole horse’s

surface.

● Not allowing short periods of walking during the cooling.

● Not allowing to drink cold water after exercise

The myth that this will lead to colic has been debunked by the University of

Guelph and Illinois since 1995

● Despite the name, no coolers on an overheated horse!

● Over supplementation of electrolytes

This can actually increase dehydration as excess sodium stimulates the kidneys to flush

it out. The perfect balance with water is necessary.


So how hot is too hot to trot?

A simple guideline is the HEAT INDEX:

Simple tool: Temperature (in F) + Humidity

If the sum is below 120 there should be no significant problem.

130-150 - your horse will sweat - but will most likely deal with it if the horse is well adapted.

Make sure to cool down properly and allow your horse access to water and electrolytes.

Above 180 - don’t even think about it! Stay home or go for a swim with your horse.

Keep in mind that there is a huge variability in heat tolerance between individuals and breeds.

Body type and body composition is also a factor. For example I have found that especially

some Friesians have problems to adapt and perform under hot and humid conditions - so

please don’t try to keep up with your friend’s lean Arabian. Be sure to be conscious of how your

individual horse reacts to and performs in each climate. Know the signs and know the limits.

Now go out, stay safe, and enjoy your horse!