Is heat a problem for horses?
In the Netherlands, a great deal of attention is (rightfully) devoted to the welfare of animals, and thus also of horses. As stated earlier: in a country with a high welfare for people there must be plenty of attention for the welfare of animals. After a beautiful (and dry) spring we are now facing even sunnier days in summer. Especially since climate scientists have warned that heatwaves will only increase in frequency and intensity in the Netherlands. At the request of the minister and in consultation with affiliated organisations and other stakeholders, the Work Group Health of the Sector Council Horses developed a ‘Protocol Extreme Weather Conditions for Horses’ in 2017 which was evaluated afterwards and adapted several times. What to do in case of ‘heat’ is extensively covered in it.
The Netherlands Food and Consumer Product Safety Authority (NVWA) recently announced that it will give protection against heat due consideration for horses that are outdoors in a pasture or paddock. Transports will also be checked. What are the areas of concern?
Horses are warm-blooded animals with a regular body temperature, rectal measurement, that ranges between 37,5 and 38,2 degrees Celsius. In case of illness, the body temperature may be slightly elevated, but above 40,5 till 41,0 degrees Celsius, damage to the body cells will occur. The ‘comfort zone’ is the ambient temperature at which a warm-blooded animal can maintain a constant body temperature with minimal effort. The comfort zone for horses is approximately between +5°C and + 20°C. That is significantly lower than that of a human. The literature is ambiguous on this topic, since the upper limit is sometimes indicated to be at 25°C or 30°C. In the Netherlands the general consensus is that the optimal stable temperature for horses is between 10°C and 15°C and for young foals between 15°C and 20°C.
Heat a problem?
If heat does become problematic to an animal or to a human, it is called heat stress. In 2007 the National Institute for Public Health and the Environment (RIVM) drew up a National Heat Plan. This plan was also amended a few times following yearly evaluations. The National heat Plan for humans aims to notify organisations, such as GGDs, sector organisation and the Red Cross Netherlands, in a timely fashion that a period of persistent warm weather is expected. Consequently, these organisations warn their following and regional contacts, who are handed measures through the Heat Plan to minimize the impact of the persistent heat. The protocol ‘Extreme weather conditions has a similar goal, namely to inform the horse industry of the risks of extreme heat (and sometimes cold) and provide all parties involved with tools about the measures that can be taken to prevent any problems.
Sweating and dehydration
If a horse sweats it loses water and various electrolytes. A horse’s sweat contains more electrolytes (such as sodium, potassium, chlorin and calcium) per liter of fluid than the blood and other body fluids. That means that if a horse sweats profoundly, relatively too few electrolytes will remain in the body. If the electrolyte concentrations in the body are low, the thirst incentive and therefore the interest to drink will disappear. That will quickly lead to problems, since horses can get dehydrated even if there is plenty of water available to them. Dependent of the conditions it may be wise to feed horses addition electrolytes on hot days when they sweat a lot. If you want to dissolve the electrolytes in drinking water, make sure the horses are still willing to drink it. For breeding and riding horses a normal ration and salt block is often adequate to meet the need for electrolytes. For top sport horses it is advisable to ask for a ration calculation for the provision of electrolytes.
In case of an ambient temperature of 30°C and higher extreme caution is advised in the transport of animals. Transport of animals that takes more than eight hours (from the Netherlands that will be transport across the national borders) is prohibited. The NVWA will not grand certificates for it. If you want to travel in warm weather, carefully plan at which time you want to drive, how the truck or lorry can be ventilated as best as possible and what the expected traffic intensity will be. Keep an eye out for traffic information and be aware that aborting a trip and going back is the wise choice sometimes. To hit a traffic jam with a horse in a truck or lorry can be detrimental to the welfare of the horse(s). When a horse truck is fully airconditioned and is equipped with drinking troughs or a stop is scheduled in every few hours to offer water, transport is also possible during (very) warm weather.
Outdoor temperature of 35°C and higher
By all involved parties in the Netherlands a temperature of 35°C or higher is regarded as too extreme to realise animal friendly transportation. No animals can be transported, regardless it being a short or long transport, unless the truck is fully airconditioned. This is stipulated in the transportation regulation. Transport of sick or injured horses to a clinic is excluded from the transport regulation and is therefore possible at temperatures ≥35°C (Regulation EG 2005/1, article 1 section 5). Of course, the temperature in the means of transportation must be carefully checked (ensure sufficient ventilation). In case of calamities, when necessary, help must be requested from the police.
Cancel events or not
In case of a predicted tropical day (outdoor temperature ≥30°C) caution is advised for horse events. Whether or not an event can be continued is dependent on other elements at play, such as the presence or absence of wind or clouds, whether a terrain has or lacks shadow and the presence or absence of sufficient drinking and cool water supplies. If the predicted outside temperature of the concerning location in the Netherlands is ≥35°C, an event with horses must be cancelled (see Protocol).
Photo: Dirk Caremans
Source: (C) KWPN (duplication not permitted)