Heat Stress in Horses: How Summer Riding Affects Your Horse — and How to Ride Safely

There is an old horseman's line worth keeping close in July: the heat does not ask permission. It builds quietly through the morning, and by the time you feel it on the back of your neck, your horse has been carrying it far longer than you have.

A horse is a large, warm, hard-working animal wearing a coat, working under a rider, in a country where the summer sun does not soften until late. When the temperature climbs, the margin for error narrows. What feels like an ordinary schooling session in April can become a genuine risk in the heat of an Egyptian summer afternoon.

This is a guide to understanding heat stress in horses — what the heat actually does inside your horse, what causes it to tip from hard work into danger, and how to read the early signs before they become an emergency. It is written for anyone who rides, trains, or cares for a horse through the hot months and wants to keep their horse cool, hydrated, and safe.

Because when it comes to summer riding, the goal is simple. Work the horse you have, and bring home the same horse — sound, settled, and well.

Why Heat Is Harder on Horses Than on Riders

Here is the truth that changes how you plan a summer ride: your horse heats up faster than you do, and cools down slower.

A working horse generates enormous internal heat. Muscles are only partly efficient, so most of the energy of movement becomes warmth that the body must shed. A horse produces heat per kilogram far quicker than a human, and it carries a much larger body relative to its skin surface — so there is more heat to lose and proportionally less surface to lose it through. Add a coat, add tack, add the weight and warmth of a rider on the back, and you have an animal working hard to stay ahead of its own temperature.

The horse's main defence is sweat. Unlike us, horses lose not just water through sweat but a heavy load of electrolytes — their sweat is saltier than their blood. In hard work in the heat, a horse can lose ten litres of sweat or more in a single hour. Equine health bodies including the American Association of Equine Practitioners stress that a heavily sweating horse needs both water and electrolytes — plain water alone does not fully restore it. That is why a summer session drains far more than energy. It drains fluid and the mineral balance that keeps muscles and nerves working.

When sweat can no longer keep pace with the heat being produced — because the air is too hot, too humid, the work too long, or the horse cannot sweat enough — core temperature rises. A normal resting temperature sits around 37.5 to 38.5°C. Hard work lifts it, which is normal. The danger begins when it stays high and keeps climbing, because a horse's organs and muscles do not tolerate prolonged high temperatures well.

Understanding that chain — heat produced, sweat lost, temperature rising — is the foundation for everything below. Every warning sign and every prevention step traces back to it.

Know Your Horse's Normal Vital Signs

Specific numbers let you catch trouble early and give your vet something useful on the phone. Take these on a calm horse at rest, ideally before the day heats up, so you know your own horse's baseline.

• Temperature: 37.2 to 38.3°C at rest. Hard work in heat can lift it to 39 to 40°C briefly, but a temperature at or above 41°C that will not come down is an emergency.
• Heart rate: 28 to 44 beats per minute at rest.
• Respiration: 8 to 16 breaths per minute at rest.
• Recovery: after work, heart rate and breathing should ease back toward normal within about 10 to 30 minutes. Breathing that stays rapid long after you stop means the horse is struggling to cool.
• Hydration: gums moist and pink with a capillary refill under 2 seconds; a pinch of skin on the neck should flatten in under 2 seconds.

One more field guide worth knowing is the heat index: add the air temperature in Fahrenheit to the relative humidity as a percentage. Below about 130, most horses cope well. From 130 to 150, take care — cooling is becoming less efficient. Above 150, and especially when humidity makes up more than half the total, a horse's ability to cool is significantly impaired and hard work should wait. Humidity is the part owners underestimate most.

8 Ways Summer Heat Affects a Ridden Horse

Each of the conditions below is a different way the same problem shows up. They share causes and often appear together, so read them as one connected picture rather than eight separate boxes.

1. Dehydration

What it is: Dehydration is a shortfall of body fluid, when a horse loses more water through sweat, breathing, and droppings than it takes in by drinking. It is the starting point for most other heat problems.

What causes it: Heavy sweating in hot work; not drinking enough, often because water is warm, dirty, or unfamiliar away from the yard; long transport in a hot trailer; and withholding water in the mistaken belief a hot horse should not drink.

Warning signs to watch for: Skin that stays tented for a second or two when pinched on the neck; tacky, dull gums instead of moist ones; sunken-looking eyes; reduced or darker urine; and a general flatness or reluctance to work.

How to prevent and manage it: Offer clean, cool water constantly, at the yard and away from it. Encourage drinking before and after work, and in small amounts during long sessions. Soaking feed and offering soaked beet pulp adds water through the gut. If a horse will not drink or the skin-pinch stays tented, treat it as urgent and call your vet.

2. Heat Stress and Heat Stroke

What it is: Heat stress is the state where a horse can no longer shed heat fast enough and core temperature climbs beyond the working normal. Left unchecked, it becomes heat stroke — a life-threatening emergency where the body's cooling systems fail.

What causes it: Intense or prolonged work in high heat and humidity; poor air movement in an indoor arena or stable; a heavy or unclipped coat; obesity; and dehydration, which cripples the horse's ability to sweat and cool.

Warning signs to watch for: Rapid breathing that does not settle after stopping; a rectal temperature above 39.5°C that stays high; heart rate that fails to recover below about 60 beats per minute within ten to fifteen minutes of rest; profuse sweating or, more alarmingly, dry skin despite the heat; stumbling, weakness, or a dull, distant expression.

How to prevent and manage it: Ride in the cool of early morning or late evening, never the mid-afternoon peak. Build fitness gradually and keep summer sessions shorter. At the first suspicion, stop, move to shade and moving air, and apply cold water continuously over the whole body. Persistent high temperature is a veterinary emergency.

3. Electrolyte Depletion

What it is: Electrolytes are the mineral salts — sodium, chloride, potassium, calcium, and magnesium — that keep muscles contracting, nerves firing, and thirst working. Heavy sweating strips them out, and because equine sweat is so salty, the losses are steep.

What causes it: Sustained sweating in the heat; long or repeated work without replacing salts; and relying on plain water alone, which replaces fluid but not the minerals lost with it.

Warning signs to watch for: Muscle tremors or twitching, especially over the flank; a poor or absent thirst response even when clearly dehydrated; fatigue out of proportion to the work; a "thumps" flutter in the flank in time with the heartbeat; and reduced performance.

How to prevent and manage it: Provide free-choice plain white salt every day, and use a balanced electrolyte supplement around hard or long summer work, always alongside plenty of water. Dr. Talia's feeding and hydration guidance below covers dosing in detail.

4. Anhidrosis — When a Horse Stops Sweating

What it is: Anhidrosis is the partial or complete loss of the ability to sweat. Without sweat, the horse loses its single most important cooling tool, and heat builds with frightening speed. It is more common in hot, humid climates.

What causes it: The precise trigger is not fully understood, but prolonged exposure to heat and humidity appears to overwork and eventually blunt the sweat glands. Any horse can develop it, and it can come on gradually over a season.

Warning signs to watch for: Dry or barely damp skin after work that should have produced a lather; rapid, laboured breathing used as a substitute for sweating; poor performance and quick fatigue in the heat; thin, patchy coat over time; and areas of flaky skin.

How to prevent and manage it: Reduce work intensity in the hottest, most humid stretches and provide shade, fans, and airflow. Cool actively with water since the horse cannot cool itself. A suspected non-sweater needs a veterinary assessment — managing anhidrosis is a long-term care plan, not a one-day fix.

5. Tying-Up and Muscle Cramping

What it is: Tying-up, or exertional rhabdomyolysis, is painful cramping and damage of the large muscles during or after work. Heat, dehydration, and electrolyte loss all raise the risk.

What causes it: Working hard while dehydrated or low on electrolytes; sudden increases in workload; and, in some horses, an underlying muscle sensitivity that summer conditions bring to the surface.

Warning signs to watch for: A stiff, short, reluctant stride; hard, painful muscles over the hindquarters and back; sweating and distress out of proportion to the work; reluctance to move; and dark, coffee-coloured urine, which is a serious sign.

How to prevent and manage it: Warm up and cool down properly, keep hydration and electrolytes topped up, and increase work gradually through the season. If a horse ties up, stop immediately, do not force it to walk on, keep it calm, and call your vet — continued work worsens the muscle damage.

6. Dehydration Colic

What it is: Colic is abdominal pain, and summer brings a specific form of it. When a horse is dehydrated, the gut contents dry out and can pack down, slowing or blocking the passage of digesta — an impaction.

What causes it: Reduced water intake in the heat; heavy sweating without replacement; a sudden switch to dry summer forage; and reduced gut movement in a horse that is stressed or unwell from the heat.

Warning signs to watch for: Pawing, looking at or kicking the belly, repeated lying down and getting up, rolling, going off feed, and passing fewer or drier droppings. Any of these in a hot spell deserves immediate attention.

How to prevent and manage it: Keep water intake high with clean cool water, soaked feeds, and soaked beet pulp. Provide salt to drive thirst. Make any forage changes gradually. Colic signs are always a reason to call the vet without delay — early is far safer than late.

7. Sunburn and Photosensitivity

What it is: Horses with pink skin and white markings — a bald face, white legs, a pink muzzle — can burn in strong sun just as people do. Photosensitivity is a more severe, reaction-driven burning that can follow certain plants or liver issues.

What causes it: Direct sun on unpigmented skin, worst around the muzzle and eyes; long turnout with no shade; and, for true photosensitivity, an internal trigger that must be diagnosed by a vet.

Warning signs to watch for: Red, sore, or peeling skin on the muzzle and white areas; crusting and weeping on pink skin; obvious discomfort when the area is touched; and, in photosensitivity, swelling and severe soreness beyond simple sunburn.

How to prevent and manage it: Offer real shade through the middle of the day, use a fly mask with a nose flap, and apply an equine-safe sun barrier to pink skin. Keep burned areas clean and protected. Severe, spreading, or repeated cases need a vet, since photosensitivity points to an underlying cause.

8. Sweat Scald and Skin Irritation

What it is: Sweat scald is irritated, sore skin where sweat sits and rubs — under tack, between the hind legs, along the girth and saddle area — often made worse in humid heat where the coat stays damp.

What causes it: Dried, salty sweat left on the skin; tack rubbing on a wet coat; humidity that stops the coat drying; and bacteria or fungi taking hold in warm, damp, unwashed areas.

Warning signs to watch for: Sore, reddened, or bald patches where tack sits; flaky or crusty skin in sweat-prone areas; sensitivity when grooming those spots; and a dull, greasy coat that never seems to dry out cleanly.

How to prevent and manage it: Rinse sweat off promptly after work and scrape and dry the coat well. Keep tack and girth areas clean, and wash sweat-prone areas with a gentle equine shampoo. A light, non-greasy coat mist can help refresh and settle the coat between full washes. Persistent or spreading skin lesions should be checked by a vet.

A Hot-Weather Riding Routine: Before, During, and After

Knowledge only protects a horse when it becomes habit. Here is a simple structure for a summer riding day, built around the heat rather than against it.

Before you ride. Check the day's heat and humidity, and plan the session for early morning or evening — the cooler ends of the day. Offer water and make sure your horse has been drinking. Pick out feet and run a hand over the coat and skin. Keep the plan realistic for the conditions; the heat is not the day to chase a personal best.

During the ride. Warm up steadily and watch the breathing. Take walk breaks in shade where you can, and let your horse drink if the session is long. Shorten the work in real heat, and finish while your horse still has something left rather than riding to empty. If the breathing turns rapid and distressed and does not settle in a rest break, stop.

After the ride. Untack promptly and start cooling straight away. Apply plenty of cold water over the whole body — including the large muscles and the big blood vessels inside the legs and neck — and keep applying it, reapplying rather than leaving the horse to steam. Scrape, walk gently in the shade, and repeat until the breathing has settled and the horse feels cool to the touch. Offer water in comfortable amounts. Rinse off sweat, dry sweat-prone areas, and cool the lower legs. Only when your horse is genuinely cool and settled is the session truly finished.

This before-during-after rhythm is the single most protective habit in summer. It turns caution into routine, so the right thing happens every ride without having to decide it fresh each time.

Dr. Talia on Feeding and Water in the Heat

The following section reflects the R&D consultation with Dr. Talia, Paw N Hoof's equine veterinarian and formulation scientist, on the two questions riders ask most in summer — how to feed and how to keep a horse drinking.

Water comes first, always. A resting 500 kg horse drinks roughly 25 to 55 litres a day. In summer heat and work, that can climb well past 70 litres. The single most important thing you can do is make clean, cool water available at all times and make it appealing — horses drink less from warm, stale, or algae-filled troughs. Scrub water containers often in the heat, and if your horse is fussy about strange water away from the yard, get it used to a familiar flavour at the yard first so it keeps drinking on the road.

On the old myth: there is no need to withhold water from a hot horse. Current veterinary understanding is that letting a hot horse drink cool water in comfortable amounts is safe and helpful — steady access supports cooling and gut health. What matters is offering it freely, not rationing it.

Salt and electrolytes. Because equine sweat carries so much salt, plain water alone does not restore what heavy sweating removes. Dr. Talia's baseline: provide free-choice plain white salt every day — most horses need on the order of 25 to 50 grams of sodium chloride daily at maintenance, and more with sweating. Around hard or prolonged summer work, a balanced commercial electrolyte replacing sodium, chloride, and potassium is well justified. Two rules with electrolytes: never give them to a horse that is not also drinking well, and never rely on them as a substitute for water — they work by drawing the horse to drink and replacing what sweat took out.

Feeding through the heat. Forage first: good hay and grazing keep the gut full of fibre, which holds water and steadies digestion. In heavy heat, lean on hydrating feeds — soaked beet pulp and well-soaked feeds add litres of water through the gut and are gentle on digestion. Feed concentrates in smaller, more frequent meals, and avoid a large grain feed right before hard work in the heat, since digestion itself generates warmth. Introduce any change to forage or feed gradually over a week or more, because a sudden switch in a dehydrated horse is a classic trigger for impaction colic. A cool, sloppy soaked mash after a hot session is an easy way to put both fluid and fibre back in.

The measurable signs Dr. Talia watches: rectal temperature (normal 37.5 to 38.5°C; concerning if it stays above 39.5°C after work); heart rate recovery (should fall below about 60 beats per minute within ten to fifteen minutes of stopping); the skin-pinch test (skin should snap back at once); and gum moisture and colour. These four are the quiet vital signs every summer rider should know how to check.

Dr. Talia on Grooming and Coat Care in Summer

Dr. Talia's consultation continued, on grooming — which in summer is not only about a tidy horse, but about cooling, skin health, and catching problems early.

Cooling with water is the priority, and the method matters. Research on hard-working horses — including cooling studies supported by the Fédération Équestre Internationale (FEI) — is clear: applying plenty of cold water continuously, over the whole body, is the fastest and safest way to bring temperature down. You do not need to scrape between every application, and cold water does not cause cramping — that is an old belief the evidence has overturned. Cover the big muscles and the large vessels of the neck and inner legs, reapply, and keep going until the horse is genuinely cool.

Wash sweat off, then dry properly. Dried sweat is salty and irritating, and left in the coat it sets up sweat scald and skin infection in humid heat. A gentle, pH-appropriate equine shampoo lifts sweat and grease without stripping the coat's natural oils; over-washing with harsh product does more harm than the sweat. After rinsing, scrape and towel the sweat-prone areas — girth, between the hind legs, under the saddle — so the skin is not left damp. Between full baths, a light coat mist and a quick wipe-down keep the horse fresh and let you handle a sweaty coat without a full wash every time.

Coat management. A horse carrying a heavy or unclipped coat into summer struggles to cool. For horses in real work through the hot months, a summer clip removes that insulating layer and helps sweat evaporate — discuss the right clip for your horse's workload. Daily grooming also matters simply because it puts your hands on the horse: it is when you find the early sweat scald, the sore white skin, the small rub, before any of them grows.

Sun and skin protection. Pink muzzles and white markings need shielding — a nose-flap fly mask and an equine-safe sun barrier on exposed pink skin through the strongest hours. Check these areas daily in summer.

Do not forget the feet. Dry summer ground and the wet-dry cycle of washing and sweating are hard on hooves — they can become dry, hard, and prone to cracking. Keep to a regular farrier schedule, and support the hoof and frog with appropriate conditioning care as part of the summer routine.

When to Call Your Vet

Some situations are past home management. Practical hot-weather guidance from bodies such as the British Horse Society agrees: some signs need a professional, not a home remedy. Call your veterinarian without delay if your horse shows any of these:

• A rectal temperature that stays above 39.5 to 40°C despite active cooling, or any sign of collapse, staggering, or a dull, unresponsive state — treat suspected heat stroke as an emergency.
• Rapid breathing or a racing heart rate that does not recover with rest and cooling.
• Signs of colic — pawing, rolling, looking at the belly, going off feed, or passing few or dry droppings.
• A stiff, cramping horse with hard, painful hindquarter muscles or dark, coffee-coloured urine.
• A horse that has stopped sweating in the heat, or one that will not drink and shows a lingering skin-pinch.
• Severe, spreading, or weeping skin or sunburn, especially with swelling beyond simple soreness.

When in doubt in the heat, cool the horse and call. An early phone call costs nothing and can change the outcome. This guide helps you recognise and prevent — diagnosis and treatment always belong with your vet.

Frequently Asked Questions

What are the signs of heat stress in horses?

The signs of heat stress in horses include rapid breathing that does not settle with rest, a rectal temperature staying above 39.5°C, heavy sweating or unusually dry skin, a heart rate that fails to recover, lethargy, stumbling, and a dull expression. Any combination in hot weather calls for immediate cooling, and if the temperature stays high, an emergency vet call.

What temperature is too hot to ride a horse?

There is no single cut-off, because humidity matters as much as heat. A useful guide adds the air temperature in Fahrenheit to the relative humidity: below about 130 most horses cope, 130 to 150 calls for care, and above 150 cooling is significantly impaired and hard work should wait. In a hot Egyptian summer, ride in the cool of early morning or evening and avoid the mid-afternoon peak.

Should you let a hot horse drink water?

Yes. The belief that a hot horse must not drink is outdated. Letting a hot horse drink cool water in comfortable amounts is safe and supports both cooling and gut health. What matters is offering clean, cool water freely before, during, and after work, rather than rationing it — a well-hydrated horse copes with heat far better.

How do you cool down an overheated horse quickly?

Move the horse to shade and moving air, then apply plenty of cold water continuously over the whole body, including the large muscles and the big vessels of the neck and inner legs. Keep reapplying rather than leaving it to steam. Continuous cold water is the fastest, safest method — and if temperature stays high, call your vet.

What is anhidrosis in horses?

Anhidrosis is the partial or complete loss of the ability to sweat, most common in hot, humid climates. Without sweat, a horse loses its main cooling tool and overheats quickly. Signs include dry skin after hard work, laboured breathing, poor performance, and a thin coat over time. A suspected non-sweater needs veterinary assessment and a long-term management plan.

Do horses need electrolytes in summer?

Yes, around hard or prolonged work in the heat. Equine sweat is very salty, so heavy sweating removes sodium, chloride, and potassium that plain water cannot replace. Provide free-choice plain white salt daily, and use a balanced electrolyte supplement for hard summer sessions — always alongside plenty of water, and never to a horse that is not drinking.

Can horses get sunburn?

Yes. Horses with pink skin and white markings — a bald face, pink muzzle, or white legs — can burn in strong sun, showing red, sore, or peeling skin. Provide midday shade, a nose-flap fly mask, and an equine-safe sun barrier on pink skin. Severe or spreading cases can signal photosensitivity, which needs a vet to find the underlying cause.

How much water does a horse drink in hot weather?

A resting 500 kg horse drinks roughly 25 to 55 litres a day, and in summer heat with work that can rise past 70 litres. Keep clean, cool water available at all times, scrub troughs often, and use soaked feeds and beet pulp to add fluid through the gut. A sudden drop in drinking is a warning sign worth acting on.

What should you feed a horse in hot weather?

Feed forage first — hay and grazing hold water and steady digestion — and lean on hydrating feeds like soaked beet pulp. Keep concentrate meals small and frequent, and avoid a large grain feed right before hard work in heat. Introduce any change gradually over a week to protect against dehydration colic, and provide daily salt.

How do you prevent heat stress when riding in summer?

Ride in the cool of early morning or evening, build fitness gradually, and keep hot-day sessions shorter. Keep your horse hydrated with free water, salt, and electrolytes, provide shade and airflow, clip heavy coats, and cool actively with cold water after work. Learn to check temperature, heart-rate recovery, and the skin-pinch test so you catch trouble early.

Conclusion: Ride the Heat With Respect

The horses that come through summer well are rarely the ones ridden hardest. They are the ones cared for most attentively — worked in the cool hours, cooled properly after, kept drinking, kept salted, and watched closely by someone who knows what to look for.

Heat stress in horses is not a rare misfortune. It is a predictable risk that answers to good routine. Everything in this guide comes back to a few quiet habits: ride early or late, keep the water and salt coming, cool with cold water and keep going until the horse is truly cool, and trust the small early signs enough to stop. None of it is dramatic. All of it is protective.

Your horse cannot tell you when the heat has become too much. It can only show you — in a breath that will not settle, a coat that stays dry, a trough left untouched. Learn those signals, and summer becomes a season you manage with confidence rather than one you survive.

Explore the Paw N Hoof horse care collection for the gentle wash-down, coat, and hoof care that supports a horse through the hot months — thoughtful, natural products for the routine that keeps your horse cool and well. For more equine care, read our guide to 10 common horse hoof problems and how to prevent them naturally.

Rooted in nature. Refined by care.