Jessica Seid, DVM
MSPCA-Angell West, Waltham
Heat stroke is a life-threatening condition characterized by an elevated core body temperature and the associated systemic inflammation that can potentially lead to multi-organ dysfunction. A dog’s normal body temperature is 98.5 to 102.5F, and heat stroke is classically defined as a core body temperature above 105.8F. Heat stroke usually occurs in the hot and humid summer months, but it can also occur under other conditions, which could include being outdoors without adequate shade and water, confinement in a poorly ventilated area, strenuous exercise, and/or being left in a vehicle even on a relatively cool day as temperatures inside vehicles can increase rapidly regardless of the outside temperature. Other factors that can contribute to development of heat stroke are obesity, pre-existing diseases affecting the cardiac or respiratory system, extremes in age (puppies or geriatrics), and some medications. Also, short-nosed breeds such as Pugs, Bulldogs, Pekingese, and Boston Terriers, just to name a few, are more prone to heat stoke as they are not able to cool themselves as effectively as other breeds. This is because their airway conformation is unlike other longer nosed breeds. Dogs do not sweat to cool themselves like humans, except from their foot pads, so their primary means to cool themselves is by panting. This is why they may not do well in temperatures that can normally be tolerated by humans. In addition, animals with a history of heat stroke tend to be predisposed to additional episodes, which occur even at lower temperatures and humidity.
Signs to watch for that could indicate heat stroke or impending heat stroke are excessive panting, thick/ropey saliva, restlessness, weakness, unwillingness to walk, vomiting, diarrhea, dry gums, and red or purple colored gums or tongue. If you are seeing any of these signs and you suspect your dog may be suffering from heat stroke what can you do? First of all, move your dog out of the heat and away from direct sunlight. If possible, bring your dog indoors to an air conditioned area or place them in front of a fan. If you have a thermometer, take your dog’s rectal temperature. Most dogs with hyperthermia will have a body temperature of greater than 105F. At this point, you can start cooling your dog by placing cool, wet towels on the neck, armpits, and groin region, or if you do not have access to towels, simply wetting your dog down with cool water from a water hose or even a lake or river can be beneficial. It is important to not use cold water or ice when cooling your dog as this can cool them too quickly and may result in hypothermia (low body temperature). When cooling your dog it is important not to overcool them, and you should stop cooling when their body temperature reaches approximately 103F, as it is very easy to make them hypothermic (low body temperature), which can result in its own problems. You can also offer small amounts of water to your dog, but do not force them to drink. Once you have started cooling, then it is important to transport your dog to a veterinary facility as soon as possible because just lowering their body temperature does not address the secondary potentially life-threatening effects that can follow. Your dog may seem to be doing better, but the possible secondary complications the elevation in temperature can cause may not be apparent to you right off the bat, so being evaluated by a veterinarian is very important.
At the veterinary hospital, your dog will be assessed by a veterinarian via a thorough physical exam, complete history regarding the events related to the heat stroke, and full blood work to evaluate organ function and clotting ability. Symptomatic treatment will be initiated which may include additional cooling measures, IV fluids, oxygen therapy, antibiotics, gastrointestinal protectant medications, blood pressure support and/or plasma transfusion. Most dogs that suffer from heat stroke require admission to the hospital or transfer to an emergency facility for hospitalized treatment and monitoring. The complications of heat stroke can be life-threatening and result in dysfunction of multiple organ systems, which most commonly include the gastrointestinal tract (gastrointestinal ulceration, hemorrhagic diarrhea, vomiting blood), clotting system (elevation of clotting times, low platelets, development of bleeding), kidney failure, liver failure, and/or damage to the brain. Heat stroke is a very serious condition and can potentially result in death. Published mortality rates range from 36%-50%, so early and aggressive care is very important in the survival of heat stroke.
Therefore, the most important thing that you can do for your dog is to prevent heat stroke from ever occurring. The things that you can do to prevent heat stroke include never leaving your dog unattended in a vehicle, even on a cool day. It does not matter if the windows are down, as this does not provide adequate ventilation and the temperature inside of a vehicle can rise rapidly in a matter of only a few minutes. If it is 70 degrees outside, it takes only 10 minutes for the temperature inside a vehicle to reach an oppressive 89 degrees. Avoid exercising your dog on hot and humid days and take your longer walks in the early morning or late evening when it is cooler and shady outside. Always provide free access to fresh water and you can even take along a travel water bowl for your dog to use on walks. If you have a puppy, a geriatric dog, a dog with pre-existing cardiac or respiratory issues, or a short-nosed breed like a Pug, Bulldog, Pekingese, or Boston Terrier, that is more sensitive to the heat, please keep these dogs primarily indoors in the air conditioning in the hot and humid summer months and only venture outside for short walks to use the bathroom and then go back inside. These dogs can still exercise during the summer months, it just should be done ideally in an air-conditioned environment. If you have any further questions regarding heat stroke or are concerned that your dog may be suffering from heat stroke, please call your veterinarian or an 24 hour veterinary emergency facility such as Angell to discuss things further, or bring your dog in for further evaluation.
For more information on the MSPCA-Angell West Emergency Service, please visit www.angell.org/emergency or call 781-902-8400.