Many horses will find hot weather uncomfortable, but the good news is there is plenty we can do to help keep them cool and reduce the risk of dehydration and colic.
A constant supply of clean and fresh water is essential to help prevent dehydration. An average horse can drink up to 50 litres of water per day in hot weather, so be prepared for this. Be aware that buckets of water in the stable can become warm and possibly unpalatable if left to stand for too long, so you may need to change them more regularly than usual to keep them fresh.
Water has a key role in your horse’s digestive system. If your horse doesn’t have access to any or enough water it can increase the risk of colic. Water is an essential component in the digestive process, and it is continually secreted into and reabsorbed from the gut. Changes in hydration can affect the digestive process and how food passes along the gut. This can increase the risk of problems such as impaction colic. If the drinking supply is from a silty natural water source this could lead to sand colic.
INCREASING WATER INTAKE
It is ideal to have more than one water source available in the field so that certain herd members aren’t prevented and chased away from drinking by others. Keeping the water source away from a corner will help prevent a horse being cornered into a small area by another horse.
You could also soak or steam your horse’s hay to increase water intake. Steaming hay (specifically alfalfa-orchard grass mixed hay) for 90 minutes increases water content by almost three times1. Remember to introduce soaked/steamed hay into the diet gradually to reduce the risk of colic. Feed the hay as soon possible after soaking/steaming and dispose of any left by the horse. Avoid soaking hay in direct sunlight and for long periods of time in warm weather as it can encourage bacteria to grow. Due to this, the current recommendation is to soak hay for around one hour in warm weather.
If appropriate, you could add a flavouring of mint or apple juice to your horse’s water to encourage them to drink.
If you cannot avoid travelling your horse in hot weather then try to travel as early or as late as possible to avoid the hottest part of the day and take more water with you than you think you will need. Some horses are fussy about drinking water away from home, so it could be essential to have a familiar supply.
Carrying plenty of water is also a vital part of being prepared if your vehicle were to break down with your horses on board. You could be stuck at the side of the road waiting for a recovery crew so water will be vital to help keep your horse cool and hydrated.
Read The British Grooms Association’s advice on Horse & Hound about what action you can take if caught up in motorway traffic.
Shelter or shade is preferable in hot weather. If your horse is turned out, a field shelter provides the best protection from the sun. The shade provided by trees and hedges may provide a good substitute, but remember that the shade will move with the sun so there may be certain times of the day when it isn’t accessible to your horse. Stabling horses through the hottest parts of the day, providing their stable remains cool, is an option to consider. However, inadequately ventilated stables can become uncomfortably hot and stuffy and suddenly changing your horse’s management can increase the risk of colic.
Flies are another hot weather menace. If you can keep your horse in during the day and out at night then their exposure to flies can be reduced. Thin fly sheets and masks can help greatly. The saliva from the bite of Culicoides midges and potentially the black fly can cause an allergic reaction in some horses resulting in the condition known as Sweet Itch (also known as Insect Bite Hypersensitivity). Intense scratching can ensue to the extent that some horses will rub themselves raw.
There are many fly repellent sprays and insecticides available but some are more effective than others. Products containing pyrethroid or permethrin are generally more effective in helping deter midges from biting. The products should be applied with care following the manufacturers’ instructions and should not be applied to inflamed or broken skin.
Remove droppings frequently from the paddock and stable to avoid attracting flies and position the muck heap away from where the horse is kept where possible.
Sun cream isn’t just for humans! Remember horses with pink skin and grey or white hair are most susceptible to burning so sun protection is highly recommended, especially on pink noses.
If you are going to exercise your horse, it is best to do so either in the early morning or late evening when it is coolest. If exercising in the hotter weather take more breaks- horses can’t be expected to do as much in hot weather as at other times if they are not acclimatised to working for longer periods in the heat. It takes 2-3 weeks of regular daily exercise in hot weather for a horse to acclimatise. Be mindful of your horse’s weight as overweight horses are likely to struggle more in hot weather.
Allowing your horse to drink immediately after exercise does not increase the risk of colic and should be encouraged.
If your horse has a thick coat (for example if suffering with Cushing’s Disease) then they may need a clip to prevent them from becoming too uncomfortable.
Don’t forget to wear hi-viz if you are riding out. Even in bright sunshine, patches of shade can make it difficult for drivers to spot horses on the road.
COOLING DOWN YOUR HORSE
After riding make sure you cool a hot horse down effectively. This can be achieved by continuously pouring cold water all over the horse’s body. Not scraping the water off the horse does not cause the skin temperature to rise and leaving water on the horse does not increase the horse’s temperature.
More information on cooling your horse can be found in Dr David Marlin’s article.
Dehydration can occur when a horse loses more water (for example lost in sweat, breath, urine and droppings) than it takes in. Knowing what is normal for your horse is important so you know when your horse isn’t right. Signs of dehydration include:
- Dark urine/reduced urination
- Reduced amount of droppings
- Lethargy and/or depression
- Dry skin and mouth
- Dull eyes
- Gums that are dark in colour
As well as water, electrolytes are also lost in sweat, breath, urine and droppings. Electrolytes are salts and minerals that help with many different bodily functions such urine production, digestion and muscle contraction. The major electrolytes are sodium, potassium, chloride, calcium and magnesium.
It can be dangerous if a horse has worked hard, lost a lot of electrolytes through sweat and is not wanting to drink. If they continue not wanting to drink then giving them a concentrated electrolyte paste may help to stimulate drinking. However, be aware if your horse is prone to gastric ulcers as electrolytes can irritate the stomach. Speak with your vet for advice if you aren’t sure whether electrolytes are suitable for your horse.
Feed electrolytes daily to horses in medium work or above (for example, competing at affiliated level, eventing, polo, endurance) rather than just during times of competition. Ensure you follow the manufacturer’s recommendations on use and dose. If you add electrolytes to water make sure the horse doesn’t mind the taste as he may not drink anything at all - offer a bucket of plain water as well.
More information on electrolytes can be found in Dr David Marlin’s article.
Heat exhaustion can be a very serious condition and can occur if the horse is exposed/exercised in very hot or humid conditions and is often also suffering from dehydration. Signs of heat exhaustion may include the signs of dehydration above and potentially:
- Fast, shallow breathing (panting)
- Nostril flaring
- Increased rectal temperature
- An irregular heartbeat
- Decreased appetite and thirst
- Slow recovery after exercise
- Muscle spasms
- Reduced performance
If your horse is showing signs of heat related illness contact your vet immediately, move them into the shade and start to cool the horse by continuously applying cold water all over the horse’s body until help arrives.
If not quickly and carefully managed, a horse suffering with heat exhaustion can progress to develop life threatening heat stroke. This may lead to the horse becoming unsteady on their feet (ataxia) and/or collapsing.
The hot weather may also affect grazing too as the sun will tend to bleach grass and dry it out; effectively your grazing has been made into hay! Although it may not look very green horses are likely to consume enough calories to sustain them as indeed they do from hay assuming that they are only in light work. But, the nutritional value of very sun dried grass maybe lower than conventionally made hay as the vitamins will have been oxidised and therefore a balancer maybe required to provide the horse with its vitamin and mineral requirement. A horse grazed on sun dried grass does not necessarily need additional forage assuming that it is not losing weight.
Before providing additional forage it is vital that you fat score (body condition score) the horse, as this will help determine whether they are getting enough calories from the grass. It is likely that they are not using as many calories compared to the winter when grass is generally not available. In addition because of the hot weather they might not be ridden as much as normal and of course they are not burning calories to stay warm.
Another way of monitoring if your horse is eating enough grass would be to monitor your horse’s poo! If you are collecting less than 1% of the horse’s bodyweight as droppings then the horse may need extra forage. Be extra careful if you own an overweight horse or a horse with an underlying disease such as Equine Metabolic Syndrome and rain is forecast. The combination of rain and sun will cause the grass to grow quickly which could increase the chances of laminitis assuming you let your horse eat too much. Be prepared to limit grazing if rain is on the horizon and introduce your horse slowly back to what will effectively be a very different forage compared to what they have been eating before the rain.
If your horse is kept on a bare paddock be aware that your horse could ingest more mud, soil or sand which increases the risk of colic, so you may need to feed additional forage to help prevent this. Remember to introduce any new forage gradually over a minimum of 10-14 days to decrease the risk of colic.
Compare grass growth in 2020 with the last two previous years by region.
Thanks to Dr Teresa Hollands, Senior Teaching Fellow (Veterinary Nutrition) at the University of Surrey for her assistance with the Grazing advice.
1) Earing, J.E., et al 2013. Effect of hay steaming on forage nutritive values and dry matter intake by horses. Journal of animal science, 91(12), pp.5813-5820.