Hot to trot

MANAGING THE HEAT

With the weather warming up again here in South Africa, preventing our horses from overheating becomes a concern. Most horses will cope fine with hot weather, but older horses, young horses, horses with health issues such as heart disease, equine asthma, Cushing’s and laminitis, or horses that are colic-prone or overweight may not cope so well. Horses that compete in certain disciplines that require a lot of effort, such as racing, endurance and eventing, can also struggle to manage their work in the higher temperatures without becoming dangerously hot.

COOLING THEMSELVES

Horses normally cool themselves down by sweating, with the sweat evaporating from the skin to create a cooling effect. Similarly, a horse’s breathing can also indicate their temperature and is another mechanism that they employ to drop their body temperature. There is a misconception that when horses breathe hard after exercise, they are struggling to get enough oxygen, but this is usually not the case. In fact, by the time a racehorse stops after a race, his blood oxygen is back to normal levels. What drives the high breathing rate is instead their temperature and a need to cool themselves down.

Cooling is critical as if the body temperature stays too high for too long, heat exhaustion can result. In extreme cases, this can lead to brain damage, organ failure and other serious, potentially deadly problems.

LOWERING TEMPERATURES ARTIFICIALLY

The quickest way to cool down a horse is to continually pour cold water on him. Whether this is from a hose pipe or other water source, the issue is really about the volume of water you can get onto them. The temperature of the water is less important overall than the amount you use. Of course, the cooler the water, the better, but don’t fixate on getting the water colder – instead, try and get more water onto him in as short a time period as possible. Studies show that continuous application of water in this way helps to remove heat through conduction – the direct movement of heat from the horse into the water. This happens due to the difference in temperature between the horse and the water. The only exception is if the water is, in fact, the same temperature as the horse, in which case the cooling effect will only come about through evaporation which is much slower than conduction.

KEEP WATERING

Spraying horses with the hose briefly or pouring a bucket of water over them before they get turned out can help keep them cool briefly through evaporation, but this is not effective for rapidly cooling a hot horse. You instead need to keep cooling until you start to see recovery signs in the horse. The best way to tell if your horse has lowered his temperature is to check if his breathing has returned to a normal rate. You can also check other vital signs such as heart rate and temperature, although rectal temperature often lags behind other signs of recovery. This is why it’s important to know what your horse’s vital signs typically are so that you can notice when they are higher or lower than average. The great thing about ‘watering’ your horse is that you can’t over-water. Obviously, if your horse starts to shiver, you’ve probably made him a bit too cold, but you can’t really over-cool.

The other aspect of ‘watering’ is providing water to drink as part of the cooling process. Horses tend to have a strong will to drink after they have finished exercising. Don’t offer them really cold water (below 10 degrees Celsius) or really warm water (above 35 degrees Celsius) in this instance. Horses generally prefer to drink water at around 25 degrees Celsius. It doesn’t hurt them to drink warmer or cooler water, but it just tends to be that they prefer water at average temperature after exercise and will thus drink more of it.

ELECTROLYTES

In hot weather, horses will sweat more and lose more electrolytes. It is essential to replace electrolytes as most horse diets are deficient in sodium. For a 500kg horse, it is commonly advised to add 25ml of salt a day and, according to the level of work, a balanced electrolyte. You need to provide electrolytes in the balance that they are lost in the sweat. It is best to give in excess than not to have enough, as the horse’s kidneys will sort out the excess. If you are considering feeding electrolytes but are not sure where to start, consult with your vet or equine nutritionist.

Horses are usually VERY keen for a drink of water after an exercise session!

THE MYTH OF SCRAPING

Scraping water off your horse will not help to cool him down. It is far more effective to leave the water on the horse. Conduction removes heat significantly faster than evaporation, so when you scrape the water off your horse, you reduce the capacity for conduction losses. Instead, leave the water on your horse on hot days to help him get cool quickly and stay cool for longer.

A NOTE ON HUMIDITY

Humidity can play a big role in the cooling of horses. The higher the humidity, the less evaporation of sweat there is. This means that horses in humid conditions are uncomfortable for more extended periods of time, recover much slower and have an increased risk of heat related illness if left to cool naturally when hot. Cooling by continuously applying water becomes more critical in these hot and humid climates, like ours, because the horse can only cool itself to some degree by evaporation. Conduction for heat loss is vital when it is humid!

Just beware the inevitable post hosing shake!!

NOTE

It isn’t just exercise that can cause a horse to overheat. Horses can get very hot in situations such as when they are stuck in a horsebox or stable on a warm day.

SIGNS OF HIGH BODY TEMPERATURE INCLUDE:

• Sweating

• High respiratory rate

• Ataxia (a wobbly gait)

• Feeling hot to the touch

• Excitability

• Stress

• Depression and lethargy.

COOLING MYTHS – BUSTED

From giving horses heart attacks to making them hotter by leaving water on them, many myths do the rounds about cooling horses. Here we dispel a few of the more common ones:

Cooling horses with cold water does NOT:

• Cause muscle damage

• Cause laminitis

• Induce shock

• Give horses heart attacks

• Prevent horses from cooling by constricting the blood vessels in the skin

Water left on the horse does NOT:

• Insulate and prevent heat loss

• Cause horses to overheat

It is NOT more effective to:

• Start at the feet and work up

• Focus on large blood vessels

• Scrape water off while cooling (as it actually causes horses to warm up!)

• Cover the horse with wet towels horse

IN SUMMARY: FIVE EFFECTIVE WAYS TO COOL YOUR HORSE

Help keep your horse comfortable in hot weather by doing the following:

• If you have brick stables with ventilation, then horses may be better in than out in scorching hot weather. However, if you have wooden stables that can get very hot, horses may be better out, particularly if shelter is provided in the paddocks.

• Unless you are specifically trying to acclimatise to the heat, avoid riding in the hottest parts of the day.

• Clean water with no additives must always be available for horses. There is an increased risk of impaction colic if water intake is reduced. If your horse is a poor drinker, then adding 1 x 25ml salt to the food should help to encourage drinking.

• If your horse or pony seems uncomfortable in the heat, hose them off and allow them to dry naturally. Don’t scrape the water off. You can do this three to four times a day.

• If you see a horse or person or dog with heatstroke, cool them down by hosing/spraying water onto them. It doesn’t have to be ice cold to be effective – just put a lot of water on!