Heat Stroke in Dogs: Signs, Treatment, Prevention

Heat stroke in dogs is a life-threatening—potentially fatal—veterinary emergency. As we get into the summer months and warmer temperatures, integrative veterinarian Dr. Julie Buzby shares symptoms, treatment methods, and tips for preventing heat stroke.

Heat stroke in dogs: When summer fun turns serious

As a mom, I love the summer. As a veterinarian, it worries me for our dogs. If the temperature and humidity are uncomfortable for us, imagine what it’s like to run around in a fur coat! Dogs can’t always effectively communicate to their owners when the heat is becoming too much to handle. That’s why it’s our job as proactive dog parents to be observant and protect our beloved furry friends.

One common misconception I’ve seen, especially on social media, is that heat stroke in dogs is easily treated with some IV fluids and veterinary outpatient care. This oversimplifies the condition and underestimates its severity.

Dogs who have experienced heat stroke will likely be hospitalized for aggressive and expensive treatment. Some of the serious complications of heat stroke will not manifest until after the initial episode, so the dog must be closely monitored from initial onset through recovery.

Let me guide you through everything you need to know about heat stroke in dogs, so you’ll be prepped when the summer temperatures rise.

Signs of heat stroke in dogs

Most dogs love to play outside. However, they aren’t always the best at knowing their own limits. If a dog owner misses the warning signs of heat stroke, even a a summer game of fetch or frisbee can go from fun to dangerous rather quickly. That’s why dog parents need to know the signs and symptoms.

Signs and symptoms of heat stroke in dogs can include:

• Heavy panting
• Dark red gums
• Vomiting and/or diarrhea
• Altered mentation
• Ataxia or stumbling gate
• Collapse
• Skin discoloration

What to do if your dog is developing signs of heat stroke

Before we go any deeper into this article, let me stop here for a PSA:

If you think your dog may be developing signs of heat stroke, get them to a cool place, offer fresh water, and call your veterinarian right away! This is an emergency.

Why does heat stroke occur?

Next, to understand heat stroke, we need a brief overview on how a dog’s body regulates temperature. The canine body, just like the human body, is calibrated to function at a very specific temperature range. A normal temperature for a dog is between 99 to 102.5 degrees Fahrenheit. It is controlled by a small part of the brain called the hypothalamus. Body temperature can be affected by both internal factors (bacterial and viral infections, for instance) and external factors (ambient temperature). 

Why a dog’s body temperature is critical

When a dog has a fever, the hypothalamus has reset the normal body temperature to a higher point. That’s why cooling a dog with a fever doesn’t actually help the fever. If you cool a dog with a fever, you bring the temperature down below what the hypothalamus has set as normal, and shivering sets in. Shivering is a compensation method to produce heat and bring the body temperature back up to the “new” normal.

In contrast, external factors do NOT reset the hypothalamus. A dog’s elevated temperature due to a hot environment is called hyperthermia rather than a fever. The dog’s temperature climbs and climbs, causing significant damage to the body. All of the organ systems run smoothest at the normal temperature range.

The dog’s body can tolerate fever for quite some time, and even overheating. It has built-in compensation methods. But once the body’s temperature exceeds around 108 – 109° F, a dog’s systems begin to break down. This is when heat stroke becomes very serious!

How do dogs cool down?

Unlike people, dogs don’t have sweat glands throughout their bodies, so sweating is not an efficient means of cooling for canines. (Dogs sweat very little and only through their footpads.) Instead, dogs rely on evaporation and convection to regulate their body temperatures. Next, let’s break these two terms down.

Evaporation occurs when dogs pant. Thus, one of the first signs of heat exhaustion in dogs is rapid, heavy panting.

Convection cooling occurs when a dog seeks a cold surface (i.e. a cool floor) on which to rest, thus transferring heat from the dog’s body to that surface. In cases where there is no mechanism to lower the body temperature (such as a dog left in a car on a warm day), heat stroke can occur quickly.

What happens when heat stroke occurs?

Heat stroke affects every single system in a dog’s body. But what is actually happening?

As an example, let’s look at a dog left in a hot car. The temperature inside the car is initially tolerable, but then it quickly begins to go up. To try to cool down, the dog starts to pant and seeks a cool place to lie down. There is no cool place, and the panting gets faster and faster but cannot effectively bring down body temperature. The blood vessels supplying the skin dilate, another mechanism for cooling. This pulls blood to the skin and away from the core.

The downward spiral begins. The dog’s central blood pressure starts to drop. The dog’s body compensates by increasing output of blood from the heart. The body does this by speeding up the heart rate. Due to the high ambient temperature, the dog’s body cannot continue to compensate, and it becomes overwhelmed. Once the temperature is 109°F, the dog’s body systems shut down quickly. Heat stroke and resultant organ failure can occur in a matter of minutes.

Which dogs are prone to heat stroke?

There are certain types and breeds of dogs that are more prone to heat stress than others. If your dog falls into any of these categories, please take heed:

• Overweight dogs —Overweight dogs can overheat rapidly. This is because the excess body fat acts as an insulator and traps heat within the body.
• Older dogs
• Boxers, Bulldogs, and other dogs with “flat” faces (brachycephalic breeds)
• Dogs suffering laryngeal paralysis or collapsed trachea
• Thick-coated dogs—Arctic breeds, such as Huskies and Malamutes, are not suited to hot environments. Yet they are frequently seen in places such as the deep South. Hot summers and thick-coated breeds don’t always mix well. Knowing your dog’s limitations is a very important part of dog ownership. 

Why brachycephalic breeds have a harder time cooling themselves

While it may seem obvious that overweight and heavily-coated dogs are at an increased risk for heat stroke, you may be wondering why brachycephalic dogs are on the list above. As explained, dogs rely heavily on ventilation for temperature regulation. Anything that impacts a dog’s ability to breathe impacts his or her ability to transfer heat.

Most dogs have relatively long snouts, and their nasal passages are highly vascular. This helps with their super sensitive sense of smell, but it also allows for temperature exchange. Dogs with short noses such as pugs and bulldogs have less space for this transfer to occur, and therefore have a harder time cooling themselves via ventilation. It is especially important to make sure your brachycephalic dog doesn’t overexert in the warmer weather.

Veterinary treatment for heat stroke in dogs

Treatment for heat stroke in dogs is not as straightforward as just lowering their body temperature. As discussed, once a dog’s body temperature get above 109°F, organ damage and failure is imminent. That concern has to be addressed before a dog can be considered out of the woods. Veterinary staff will work methodically and take multiple steps to treat heat stroke.

Your veterinarian will cool your dog down

Yes, cooling is certainly part of treatment for heat stroke. That being said, there is some controversy in the veterinary community with regard to the best method for cooling. Generally speaking, especially for dogs with thick coats, I will wet their fur with cool water and apply ice packs wrapped in towels to their bellies and armpits.

During the cooling process, it is critical to keep an eye on body temperature, and to stop cooling when the dog’s temperature reaches 103.5°F. If cooling is too aggressive, then a rebound hypothermia will occur, and the dog’s body temperature will be too low. 

IV fluids

The next step in treatment after starting to cool a dog off is to start IV fluids. Fluid therapy serves several purposes in this scenario:

• A dog having a heat stroke is in shock. This means blood pressure is low, heart rate is high, and circulation is poor. With poor circulation, oxygen delivery to tissue is decreased. Oxygen is essential for normal body function. IV fluids bring temperature down while promoting circulation. 
• Heat stroke in dogs can also cause issues with kidney function. Just like every other organ system, severely high body temperatures can damage the kidneys. Administering IV fluids helps to support kidney health.
• Dogs experiencing heat stroke may have electrolyte imbalances. IV fluids are balanced electrolyte solutions, so they can keep things stable while the dog’s body focuses on recovery.

Oxygen therapy

Oxygen therapy is also important when treating heat stroke in dogs. While the circulatory system is struggling to get oxygen to tissues, your veterinarian can help it out by increasing the amount of oxygen the patient is breathing. That maximizes efficiency of every heart beat, pumping higher oxygenated blood to the tissues, which takes some of the stress off the heart.

Medications to treat symptoms like diarrhea, vomiting, and life-threatening infections

Many dogs with heat stroke exhibit signs of nausea— excessive lip licking in dogs, retching, and drooling. The gastrointestinal tract cells are extremely sensitive to heat damage. Vomiting and diarrhea are common symptoms of heat stroke.

With heat stroke, the cells lining the stomach and small intestines start to die. This is a problem for two reasons. First, that lining is critical in maintaining a barrier between the intestines (full of bacteria) and the bloodstream (sterile—no bacteria!). Second, absorption of nutrients through the gut is critical.

When those cells are damaged by heat, nausea and bloody diarrhea often result. As the barrier breaks down, bacteria can enter the bloodstream. This leads to life-threatening systemic infection (called sepsis or septicemia).

Antibiotics can be critical for treating sepsis. Anti-nausea medications can also help affected dogs feel better. 

Severe heat stroke in dogs

In some instances, organ and tissue damage is severe, and beyond the scope of treatment in a typical general practice. Your regular veterinarian may stabilize your dog, and then recommend transferring him or her to a 24-hour referral hospital for intensive care for heat stroke in dogs.

Blood not clotting: A sign of severe heat stroke in dogs

Once body temperature reaches 109°F, the blood clotting system in the body starts to break down. Clotting factors are made in the liver. Like the rest of the body, they are sensitive to internal temperature. At 109°F, clotting factors no longer function. Red spots on the dog’s skin—called petechiae—are one of the earliest manifestations. As they spread and merge into large patches, they are called ecchymotic hemorrhages. The image below shows what these large, red patches may look like.

Dogs with this clotting issue need a plasma transfusion. Plasma is one component of blood. It contains important proteins including clotting factors. Most general practices do not keep plasma on hand. It is expensive and requires specific storage and handling. Dogs with abnormal clotting who are unable to receive a plasma transfusion in a timely manner are at risk of death.

5 tips for preventing heat stroke in dogs

Whether or not your dog is prone to heat stroke and falls into one of the at-risk categories outlined above, there are things you can do to keep your dog safe in hot weather. Here are five helpful tips to keeping your dog cool, safe, and happy:

1. Do not exercise at-risk dogs in the heat.

In the summer, at-risk dogs should NEVER be exercised in the heat. Walks should be in the early morning, before the heat of the day, and at twilight or after dark. 

2. Bring dogs inside on hot days.

It goes without saying that dogs kept outside in the summer should always have access to shade and fresh, cold water. But, seriously, dogs living in hot climates need to be brought indoors where they can cool off!

3. Don’t leave your dog in the car unattended.

Never, never leave a dog confined in a car with the windows rolled up. Truthfully, it is safest never to leave dogs in parked cars, even with the air conditioner running. Recently, a colleague reported a client leaving two of their dogs in a running RV with the air conditioner blasting. They left for a few hours, and when they returned, the A/C had failed. Both dogs suffered heat stroke, and only one survived. Air conditioners break! It is always best to leave your dogs at home when running errands, unless you are visiting dog-friendly establishments.

4. Know your dog’s limitations.

By simply keeping your dog cool, not exposing him or her to hot or humid conditions, and knowing your dog’s limitations, heat stroke is preventable. When in doubt, the best approach is to keep your canine companion safely at home in the air conditioning with plenty of fresh water!

5. If your dog suffers from laryngeal paralysis, be especially vigilant.

Dogs with laryngeal paralysis or tracheal collapse are uniquely prone to heat stroke. This occurs because of upper airway obstruction. Since they cannot pant well and ventilate appropriately, they quickly become distressed. This is one of the most common reasons for a dog to have a heat stroke, second only to being left in a hot car. 

Protect your dog’s paws from the heat too

Don’t forget to protect your dog’s paw pads. On a hot day, the temperature of pavement is significantly higher than air temperature. Hot pavement can cause severe damage to paw pads. If the pavement is too hot for you to comfortably touch with your bare hands, it’s too hot for your dog to walk on! Keep your pup indoors or on unpaved surfaces for outdoor excursions.

Charles, a St Bernard dog, collapses from heat stroke

Finally, I’d like to share the story of Charles, the first dog that I ever treated for heat stroke. Of course, I’d studied heat stroke in veterinary school. But studying about it in a textbook and seeing the suffering dog lying before me on a gurney were quite different. 

It was July in the South. Need I say more? Picture humidity so thick that the mosquitoes were choking.

One of my favorite patients, Charles, was boarding at a local doggy daycare. He’d been outside, in the 90+ degree heat, frolicking with his friends when he’d suddenly collapsed.

The boarding facility called in a panic, letting us know they were bringing Charles straight in. I prepared my staff for his arrival.

Veterinary treatment

When he arrived, Charles couldn’t walk. He looked melted in the back of the SUV, panting so heavily that I couldn’t understand how he was able to ventilate himself. His tongue lolled out to the side, and his eyes were panicked. I could feel the heat radiating from his body.

My staff jumped into action by carefully lifting him onto a stretcher and bringing him into the hospital. One vet tech began shaving Charles for an IV catheter to start cool intravenous fluids while the other technician took the St Bernard’s temperature and got his heart rate. (As an aside, knowing your dog’s vital signs just might save his or her life someday. Please learn how to assess dog vital signs.)

Charles’ temperature was an astounding 111°F. 

My hospital doesn’t have overnight care, so our goal was to stabilize Charles before transferring him to the local 24-hour specialty veterinary hospital. He would need days of critical care. Even with all that modern veterinary medicine has to offer, his prognosis (expected outcome) was “guarded.”

Our veterinary team started by cooling him with water, a fan, and ice packs. Next, we placed an IV catheter and started IV fluids. Then, we lined an oxygen mask with ice to deliver cooled oxygen.

Diagnostic testing

When Charles first arrived and we placed the IV catheter, my forward-thinking technical staff had obtained blood samples right away. We ran two tests on the in-house bloodwork machines—a complete blood count (CBC) and a chemistry panel.  A complete blood count is exactly what it sounds like! The blood components—red and white blood cells and platelets are counted.

In dogs with heat stroke, alterations in these numbers happen fast. As expected, Charles’ platelets were low (the first step in the clotting cascade discussed above), and his white blood cell count had fallen as well. This is because of heat damage to the bone marrow, where those cells originate, but also because of the body’s overwhelming inflammatory response to heat stroke “tying up” those cells. 

A chemistry panel evaluates the organs and electrolytes. Already, Charles had alterations in his kidney values—BUN and creatinine (elevated)—and his liver enzymes. His blood sugar was also dangerously low at 50 (normal range is 75-120). All of these changes are to be expected in dogs with heat stroke, as every organ in the body is damaged. Electrolytes (like sodium and potassium) can also be deranged, although Charles’ were normal. 

I added dextrose, a synthetic sugar, to his IV fluids to bring his blood sugar back to normal. His temperature was down to 103°F, and my technicians had removed the fan and ice packs. It was time to transfer him to the referral hospital.

One dog’s full recovery from heat stroke

I strive to tell you stories of hope and happy endings, and Charles is one of those stories. Under our care and then the care of a 24-hour hospital, he survived. He received three units of fresh frozen plasma and remained hospitalized for five days on IV fluids, antibiotics, and GI protectant medications for his damaged gastrointestinal tract. His blood sugar levels fluctuated, and he needed dextrose supplementation to fuel is cells. His veterinary bill for the incident was several thousand dollars.

He could have died, and it’s a miracle that he didn’t.

Heat stroke in dogs is preventable

There are two uplifting takeaways here: Charles survived AND heat stroke (in all but the rarest cases) is absolutely preventable. When the temperatures rise, there’s no need to risk it. Preventing heat stroke means avoiding risky situations in the first place, being mindful of your dog’s limitations, and knowing whether your dog is prone to heat stroke.

As you’re enjoying upcoming summer activities, please share this article to help educate other dog owners. With knowledge and information, we won’t need a stroke of luck to prevent heat stroke in dogs.

What questions do you have about heat stroke in dogs?

Please comment below.