Heat-Stroke in Dogs: Signs, Treatment & Prevention Expert Advice

Mostly sunny days and temperatures around 24C sound like the perfect weather for a fun-filled outing with your pet, right? For the most part, the answer is ‘yes’, but these are the days when you have to be extra cautious about heat-stroke in dogs. Dogs can quickly die from heat-stroke – not only from being left in an unattended car in hot conditions, but also from sunny and over 20C weather.

What is heat-stroke in dogs?

Heat-stroke in dogs, also known as hyperthermia, is a severe and life-threatening emergency that occurs when a dog’s body temperature rises to dangerous levels, typically over 40C. The normal body temperature of a dog is 38C–39.2C. High temperatures, excessive physical activity in hot weather or confinement in a hot and poorly ventilated car are the typical culprits of this condition, but it can happen even in mild temperatures. Heat-related illnesses come in three stages, each leading to the next if left untreated.

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• Heat stress: heat stress is a precursor to the more severe heat-related illnesses. With heat stress, dogs may have increased thirst and panting but can generally walk and behave normally.

• Heat exhaustion: heat exhaustion, a milder form of heat-stroke can occur if a dog’s body temperature rises above 39.4C. Signs of heat exhaustion in dogs may include excessive panting, increased thirst, weakness, fatigue and potential collapse. If heat exhaustion is left untreated, it will result in heat-stroke.

• Heat-stroke: it’s crucial to seek medical attention immediately if your pup is experiencing this serious condition. If left untreated, prolonged exposure to high temperatures and heat exhaustion can result in organ failure and potentially lead to death.

Many people are unaware of how dogs process heat and how easily dogs can succumb to heat-stroke. Dogs cannot tolerate high temperatures as well as humans because they depend upon rapid breathing (panting) to exchange their warm body air for cooler environmental air. When the air temperature is close to body temperature, cooling by rapid breathing is no longer an efficient process, and dogs can succumb to heat-stroke in a relatively short time.

Common causes of heat-stroke

Leaving a dog in the car with ‘the windows cracked’

It’s not safe to leave dogs in a car, even in mild temperatures. If left in a car on a relatively cool 23C day, the temperature within a vehicle can increase an average of 4.5C within one hour. That equates to 28.5C in the car, whether the windows are ‘cracked’ or not.

When an animal is left outdoors or exercised in hot or humid weather

You might be surprised how many pets have developed heat-stroke while out for a routine walk. One risk factor is short legs. Dogs with short legs are closer to the pavement which radiates additional heat, contributing to the development of heat exhaustion or heat-stroke. It is important that dogs have adequate shade when outdoors.

Other factors that increase the risk of heat-stroke

Risk factors that make dogs more susceptible to heat-stroke include age (puppies and seniors are at higher risk), obesity, size (over 50kg), age (over 2 years old), existing breathing or heart conditions and brachycephaly. Brachycephalic breeds are short-nosed, flat-faced dogs such as a Pekingese, Pug, Lhasa Apso, Boston Terrier or Bulldog (including the English and French Bulldog). These dogs suffer from an elongated soft palate within a short face. This means excessive soft tissues that can obstruct breathing (referred to as BOAS: Brachycephalic Obstructive Airway Syndrome). BOAS interferes with their ability to pant, and can be fatal. These dogs are more than four times more likely to be affected by heat-related illness.

Signs of heat-stroke in dogs

Initially, the main symptom of heat-stroke in dogs is excessive panting. Dogs suffering from heat-stroke will appear distressed and become restless. As the heat-stroke progresses, the dog may drool large amounts of saliva from the nose and/or mouth and may even become unsteady on their feet. You may notice the gums turning blue/purple or bright red, which is due to inadequate oxygen. Dogs suffering with heatstroke may show some or all of these signs:

• distressed and restless behaviour

• excessive panting

• excessively drooling

• pale, blue, purple or bright red gums

• brightened tongue

• rapid breathing

• increased heart rate

• glazed eyes

• confusion

• vomiting

• diarrhoea

• lethargy

• weakness

• seizures

• collapse

How to treat heat-stroke in dogs

Severe heat-stroke is a disease that affects nearly every system in the dog’s body. Simply lowering the body temperature fails to address the potentially catastrophic events often accompanying this disorder. A dog suffering from heat-stroke should be seen by a vet as soon as possible for appropriate care. Here’s what you should do if you suspect your dog has heat-stroke:

1. Immediately move your dog to a shaded and cool environment.

2. If possible, determine their rectal temperature and record it. Do not worry about this step if it is not feasible.

3. Begin to cool their body by placing wet towels (use cool tap water) over the dog’s back of the neck, armpits and groin region. Refresh often.

4. Wet the dog’s ear flaps and paws with cool water.

5. Direct a fan to the wet areas to speed up evaporative cooling.

6. Transport your pup to the closest available vet immediately.

Most dogs with heat-stroke have body temperatures greater than 40C, and a reasonable goal of cooling is to reduce your pet’s body temperature to between 39C and 39.5C while transporting them to the closest veterinary facility.

Once your pup arrives at the vet, they can provide better diagnostic tests and supportive treatment for heat-stroke and the associated complications. Your vet will aim to improve blood circulation, balance electrolytes and treat any secondary effects. If your pup has a thick undercoat, it may be shaved to help increase cooling. Your vet will likely provide your dog with oxygen therapy at the time of their hospitalisation.

What NOT to do during a heat-stroke

Avoid using ice. Rapidly cooling off the dog is extremely important but do not use ice cold water for cooling! While ice may seem logical, its use is not advised. Ice will cause superficial blood vessels to shrink (vasoconstriction), effectively forming an insulating layer of tissue to hold the heat inside. This causes the cooling of the body’s innermost structures to actually be delayed – which is the opposite effect that you want. Cool tap water is more effective for cooling.

Avoid forcing water. Keep an eye on your pet and do not leave them unattended for any length of time. Do not attempt to force water into your dog’s mouth. You may have fresh cool water ready to offer should your dog be alert and show an interest in drinking.

How can I prevent heat-stroke in my dog?

There are a number of things you can do to prevent heat-stroke in your dog.

• Make sure your dog has access to plenty of fresh, cool water at all times.

• Avoid exercising your dog on hot days.

• Avoid strenuous exercise during the hottest part of the day, between 11am and 5pm.

• Never leave your dog in a parked car, even in mild weather or ‘just’ for a few minutes.

• Make sure your dog has a shady spot to rest in.

• Cool off your pup with a damp cloth.

• Plan to give your pup plenty of breaks.

• Don’t leave your dog alone in a garage or other enclosed area.

• Avoid walking on sand, concrete or other hot surfaces which may reflect heat.

What are the potential complications of heat-stroke in dogs?

Heat-stroke is very damaging to the body, so the prognosis is poor. In UK emergency vets, over 25 percent of dogs affected with heat-related illness die, often due to multi-organ failure or abnormal bleeding and excessive clotting (disseminated intravascular coagulation). Most deaths occur within 24 hours and survival past 48 hours usually results in a good prognosis. Some dogs suffer from long-term effects such as permanent organ damage requiring life-long care. Immediate treatment will give your dog the best chance for survival. Some complications of heat-stroke include:

• seizures

• organ failure

• abnormal bleeding

• excessive blood clotting

• neurological (brain) damage

• heart arrhythmias

• secondary infections

What if I see a pet in distress?

It is strongly advised across the UK not to leave dogs unattended in vehicles, yet it is still a common sight. If you do happen to see a pet in distress dial 999 at once. They are authorised to take all steps necessary to remove an animal from an unattended car.

Frequently asked questions

Are there any first aid measures I can take for a dog with heat-stroke?

Dogs with heat-stroke should be immediately taken to the vet. While in transit, utilise first aid measures to help cool your dog: apply wet, cool towels on the dog’s back of the neck, armpits and groin region, then use a fan to help evaporate the heat.

How does heat-stroke occur in dogs?

Heat-stroke is a devastating condition that occurs when a dog overheats and cannot cool off on their own. Unlike humans, dogs cool themselves by panting, rather than sweating through their skin, which makes them much more susceptible to heat-related illnesses.

What are the potential complications of heat-stroke in dogs?

Potential complications for heat-stroke in dogs include seizures, organ failure, blood clots, excessive bleeding, brain damage, heart problems, infections and even death.

How can I prevent heat-stroke in my dog?

You can prevent heat-stroke in your dog by providing ample access to fresh cool water, providing them plenty of shade, avoiding exercising in the heat and never leaving your dog unattended in a car.

What should I do if I suspect my dog has heat-stroke?

If you suspect your dog has heat-stroke, you should apply cool, wet towels on your dog’s neck, armpits, and groin area, offer them cool drinking water, then rush to the vet immediately. Early treatment can significantly improve your pup’s chances for recovery.

When should I seek vet help for a dog with heat-stroke?

You should seek vet help immediately if you suspect your dog has heat-stroke. The sooner they receive care, the better their prognosis. Call ahead to ensure your vet is available or take them to an emergency vet.

Can heat-stroke be fatal for dogs?

Yes, heat-stroke in dogs can be fatal. If you suspect your dog is suffering from this life-threatening condition, you should take your dog to the vet ASAP.

References:

• A Novel Severity Scoring System for Dogs with Heatstroke

• Heatstroke in Dogs: Clinical Signs, Treatment, Prognosis, and Prevention*

• Pathophysiology and Pathological Findings of Heatstroke in Dogs

• Pathophysiology of Heatstroke in Dogs – Revisited

• Pathological Findings in Dogs with Fatal Heatstroke

• Today’s Veterinary Practice - Heatstroke in Dogs

• Canine Heat Stroke

• Heat Stroke in Dogs (what you need to know)

• Treatment of Hyperthermia and Heat-Induced Illness

• Management of Heat Stroke in the Dog

• Epidemiology of heat-related illness in dogs under UK emergency veterinary care in 2022