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Heat Stress Control


TESH-International is a company which specializes in developing and marketing Horse Cooling Units (HCU). These HCUs are increasingly important for controlling heat stress in sport horses, a phenomenon which is, tragically enough, severely underestimated by riders, owners, grooms and stable people. The HCUs are basically the only means for optimally controlling heat stress at the finish of e.g. cross-country competition, endurance and intensive training. Heat stress occurs when the ambient temperature rises above 24°C (75°F) while at the same time the air humidity is above 70%. The horse cannot get rid anymore of its body heat accumulated during the preceding performance. HCUs are designed in such a scientifically justified and practical way that the negative consequences of heat stress for further horse performance, health and wellbeing are limited in the best possible manner. Check out details in the following paragraphs. Thank you for your interest in TESH-International and Horse Cooling Units,

Tom Noordhuizen, CEO of TESH-International.


Definition & signs of heat stress

A horse regulates its body temperature, depending on ambient temperature and air humidity, and on the level of performance, hence nutrition and metabolism. Like all animal species, a horse has a “thermo-neutral zone” in which it can increase or decrease body temperature without any effort, following normal biological pathways. The thermo-neutral zone of the average horse is between +5°C (42°F) and +23°C (73°F). In addition, it has a “comfort zone” in which the horse feels at its best; this zone is between +15°C (60°F) and 20°C (70°F). Heat Stress is defined as the situation in which a horse’s body temperature rises above a certain physiological threshold level where it cannot longer get rid of accumulated body heat by sweating (normally around 70%), respiration (normally around 20%) and radiation (normally around 10%). Heat stress may already occur at ambient temperatures of 20°C (70°F) or higher, while at the same time the air humidity is above 70%. The horse losses body fluids by urine and faeces, and the accumulated body heat cannot be evacuated anymore because proper sweating function is largely hampered.

This accumulated body heat leads to a variety of more or less detectable signs: increased heart rate (> 50/min), increased respiration rate (> 40/min), increased rectal temperature (> 38.5°C (98°F)) ,extensive sweating or no sweating at all, feed refusals, stiff gaites, diarrhoea, signs of colic, immune-suppression (hence more susceptible for infectious diseases), changes in its behaviour (frequent neighing, depressive, loss of attention), decreased elasticity of the skin in the neck, capillary filling time in the mouth mucosa is retarded. These signs are not all present at the same time; moreover, some of them cannot be detected from the outside.

The probability diagnosis is hence based on a combination of relevant signs: abundant sweating/no sweating; high rectal temperature; increased heart rate; increased respiration rate; behavioural changes; elasticity test (pick up skinfold in neck and let go: skin should be back in 3-4 sec); mucosa test (press your thumb on the violet mucosa above the teeth in the mouth for 4 sec and let go again: normal rose colour should be back in 2 sec); infrared thermo-graphic reading of the skin (skin temperature should be lower than 30°C (86°F). You need experience to set the proper diagnosis.


Most often made errors when trying to cool down a horse

Some people do not apply any cooling to their horse in spite the fact that their horse truly needs it. Mostly this is because those people do not really know their horse, or its biological needs; in fact, it is poor wellbeing or cruelty.

Other people do their best to apply some sort of cooling but do not know the basic principles. The latter often leads to a poor end result, no cooling at all, or counterproductive effects. Among the most often made errors are:

  • Using ice-water to cool down the horse, or napkins drenched in ice-cold water. The ice closes down the skin capillaries which then are not able to pass on the hot blood. Cooling takes not place. Leaving the napkins on the horse is even worse: evaporation cannot take place at all.
  • Throwing cool water on the horse using buckets: this is hardly or not effective, very time-consuming, labour-intensive, and the end-result is far from optimal. The same goes for showering a horse: it is inappropriate.
  • Using misters/foggers to bring water on the horse. Unfortunately, the tiny small droplets remain on the surface of the hair and never reach the skin. Cooling is not optimal at all. Moreover, wind can blow away the fog/mist.
  • Not using rubber drawers to wipe off the warm water from the skin before applying new cool water.
  • Fans –if used- are set at a too high speed which frightens off the horse and does not feel good for the horse.
  • Applying cooling during a too short duration to be effective.
  • Applying cooling without checking the signs named under the heading 'diagnosis'.
  • Applying a kind of cooling following the human feeling point of view (and not the horse’s).









Horse cooling units, HCU

The idea of HCU was conceived by professor Jos Noordhuizen (DVM, PhD, former Diplomate of the EC BHM and the EC VPM), who has been associated with the Universities of Utrecht and Wageningen, University of Gent, the Veterinary Schools of Nantes and Lyon, and Charles Sturt University, Australia. The concept has been further developed, elaborated and marketed by Mr. Tom Noordhuizen. The latter in cooperation with, among others, prof.dr. Gunther van Loon (Veterinary Faculty, dept. of Cardiology, Ghent University, Belgium) who conducted the tests.

The HCU is designed in such a way that a horse will feel completely at ease and shows an increased well-being when cooled down in the HCU. The HCU is a patented design.

A HCU is a dismountable, fully open, metal structure with a patented design, on which a specifically designed sprinkler with hood and two particular fans are mounted. The sprinkler imitates the natural rainfall in a certain debit of water, by which the horse is drenched up to the skin. The sprinkler functions during 1 to 2 min, after which the warm water is wiped off the skin, and before the two fans are activated at low speed. Fans run during 2 to 3 min. This is called a “cooling cycle”. The open structure allows for a complete body drenching and fanning (including leg muscles and tendons) because there are no true obstacles. Some horses are sufficiently cooled down after one cycle, while others need one or two cycles more. Evolution during cooling is checked, following the clinical tests indicated under the heading of "diagnosis". Heart rate and heart function can be easily monitored and recorded through developed Bluetooth ECG connection.

HCUs can be equipped further with accessories, such as flood light to continue cooling in the evening or night; or a water tub in which used water can be collected and, after filtering, recycled. Furthermore, HCUs could be coloured in the RAL colour desired by the client (using powder coating).

Individual stables may prefer a few individual HCUs, while organizing committees of (international) equestrian competition may prefer combinations of HCUs (three-, six-, nine- or twelve-fold combinations of HCUs in either a carousel format or a cooling alley format where several horses can be cooled simultaneously) to increase efficacy of the cooling process at the finish of cross country, endurance and other eventing, for several horses at the same time.






Photos and videos

PDF info


In this part of the TESH-International you will find a package of PDF documents. These documents concern : a series of practical aids (fact sheets) for controlling heat stress in the field and avoid errors ; a recent review article on heat stress in sport horses ; and other points of interest when dealing with heat stress (summaries numbered from Heat 1 to Heat 8). This package of PDF files can be obtained, if you first fill out the order form and do your payment to our bank account. The package will be sent to you by E-mail as soon as payment is received. Thank you for your interest in these heat stress control documents and TESH-International.

Price: € 100

You can transfer the amount of € 100 to the following  bank account of TESH-international:

ABN AMRO bank account with IBAN : NL19ABNA 0578 6534 27 on the name of TESH-international (Tom M. Noordhuizen).

Order form (the pdf-bundle of practical heat stress management documents.)