April showers brought May flowers, and now the June sunshine is coming! Kids are getting out of school, parks and swimming pools are filling up, and pets are outside enjoying the warmth with us! This weather is perfect for snow cones and lemonade, but it sure is tough on those family members who live life in a fur coat!
Heatstroke is a serious and, unfortunately, common event that happens when it gets hot outside. The definition of heatstroke is a marked elevation of body temperature (>105.8*F). The most common causes of heatstroke in our pets are confinement in a hot car, epilepsy, exercise (playing or intentional) in hot weather, high humidity, and obesity. There are certain breeds that tend to be more sensitive to heat and are not able to properly cool themselves. The majority of these breeds are the brachycephalic breeds (flat-faced dogs such as Bulldogs, Pugs, Boston Terriers, etc). While each case of heatstroke can look different, there are common signs that you should watch for in your pet. These are a fast heart rate, fast breathing, salivation, abnormal gum color, and collapse. In severe cases, the pet can have seizures and even go into a comatose state. While just these outside symptoms can be scary to witness in your furry loved one, the internal injuries are just as scary. I want to take a minute to talk about those so that you can understand what your veterinarian will be thinking about when you bring in your pet.
The cascade of events inside your pet’s body goes like this: cardiac output (how much blood the heart is pumping out) increases because of vascular dilation. Eventually, cutaneous and splanchnic (spleen) blood pooling occurs followed by dehydration. Dehydration and blood pooling together lead to hypotension (low blood pressure) and hypovolemia (not enough fluid in the vascular system). This causes the cardiac output to then decrease, which in turn makes it even harder for the animal to release heat. The body temperature continues to rise which will cause a cascade of events that lead to clotting problems and organ damage. I’ll take you through each system so I can explain the possible outcomes.
Gastrointestinal Tract: Low blood flow and high temperatures lead to ischemia (damage due to not enough blood). This damage allows bacteria in the intestinal tract to leak into the vascular system leading to infection of the blood. It is also common for the intestinal tract to bleed during heatstroke, so you may see dark or bright red blood coming from the anus. Your pet may also vomit blood.
Central Nervous System: Disorientation, stupor, seizures, and coma may occur due to low blood flow to the nervous tissues (brain, spinal cord, nerves), bleeding in the nervous tissues, and necrosis of the tissues.
Kidney: Acute kidney injuries are a common consequence of heatstroke. This occurs due to low blood flow to the kidney, direct thermal injury, and systemic inflammation. Breakdown of muscle due to the excessive heat releases particles that are also toxic to the kidneys.
Heart and Lungs: Thermal injury can cause the heart muscle to bleed and die. The heart can also have arrhythmias (irregular heartbeats) due to the low blood flow, lactic acidosis, or electrolyte imbalances. The lungs can have fluid build-up or may begin to bleed.
Blood: Heatstroke patients are at an increased risk of DIC (Disseminated Intravascular Coagulation – a state of excessive clotting that leads to hemorrhage because all of your pet’s clotting factors are used up). Platelets (an important cell used in clotting) can be damaged from the high temperatures. If the patient enters DIC, they have an extremely poor prognosis.
So, that all sounds pretty scary, and to be really honest, it is!! Heatstroke is a dangerous and life-threatening condition. So, let’s talk about the ways we can prevent it and what to do if you think your pet is experiencing heatstroke. The best way to prevent heatstroke is to keep your pet indoors during the hot parts of the day during the summer and fall. If you have to leave them outside, it is very important that they have easy access to shade and plenty of water that has no chance of running out (it should be checked regularly because the pet can knock it over without you knowing). Never leave your pet in the car without the air conditioner on – even if the windows are down, it is still WAY too hot to leave them even for a few minutes. If your pet is one of the breeds that is sensitive to heat, you must be even more careful. If you regularly exercise with your furry loved one, be sure to do so in the early morning or late evening. Also, be sure to stay on the grass if possible because hot cement or pavement can burn the paw pads. If you think your pet is experiencing heatstroke, immediately call your veterinarian or the nearest emergency clinic. You can start cooling your pet by placing wet towels on your pet that are pre-soaked with cool water. You can run the air conditioner on them while in the car. Do not place ice on them because this causes vasoconstriction that decreases heat loss.
Once you arrive at your veterinarian’s clinic, the doctor will want to immediately assess the condition of your pet. This will include a thorough physical exam and other diagnostics such as blood work, radiographs, and an ECG of the heart. Possible treatments may include active cooling techniques, IV fluids, oxygen therapy, antibiotics, gastrointestinal protectants, and hospitalization for monitoring.
Again, heatstroke is a scary and serious condition, but the good news is that it is completely preventable!! So, enjoy the summer with your family and furry loved ones, but stay safe!
About the Author
Dr. Heritage Enevoldsen