By Dr Justine Wimpole, BVsc
Heatstroke is a very serious condition caused by a marked elevation in body temperature. It usually occurs on hot or humid days especially if a dog has been confined to a hot place such as a car. Dogs can also become overheated after too much exercise and over exertion.
Dogs do not sweat significantly and instead control their body temperature by increasing their rate of breathing and panting. If a dog’s breathing is compromised this increases the risk of heatstroke. Things that cause problems with breathing are often due to structural problems with the upper airway (the back of the mouth, throat and voice box or larynx). Dogs with problems in this area will often have very noisy breathing and they may also snore excessively. Problems with the upper airways often occur in dogs with shorter noses including Bulldogs, pugs and Staffordshire Bull Terriers. Older large breed dogs such as Labrador Retrievers can also suffer laryngeal (voice box) paralysis and have breathing problems. You should take special care to avoid these dogs overheating especially on hot or humid days or else they will almost certainly overheat.
Dogs that have been locked in cars or confined to other hot areas on hot or humid days are also at risk of suffering heat stroke. The risk is increased because they often do not have access to water. Often dogs can suffer heat stoke after being confined to a sealed car, even for only a very short time.
Heat stroke affects the entire body and can cause anything from only very mild signs to very severe and life threatening conditions. Dogs suffering heat stroke will usually have an elevated body temperature (greater than39.5oC). You should take your dog’s temperature rectally. Sometimes a dog suffering from heat stroke may have had a chance to cool down and have a normal or only slightly elevated temperature by the time that you measure it. Other signs that your dog may show include persistent panting and agitation, brick red coloured gums, dullness, nausea, vomiting and diarrhoea, an elevated heart rate (greater than 120 beats per minute), weakness and muscle tremors. When it is more severe they may become confused, collapse and may have convulsions.
If you suspect that your dog has suffered heat stroke and has an elevated temperature then you should try to cool them down and take them to your veterinarian as soon as possible. The best way to achieve both of these goals in a timely fashion is to spray their coat with cool water or cover them with a wet towel and take them to your veterinarian immediately. You should turn your car’s air conditioning to maximum or at least open the windows. You should also take this approach if your dog is collapsed, convulsing or non-responsive.
If there is going to be a significant delay in seeing your veterinarian you can try to cool them down more aggressively yourself. Firstly you should take the dog out of the sun or the hot area, and move them to a cooler shaded place. You should then offer them water. If your dog’s temperature is less than 40.50C, you should place a fan in front of them. Take their temperature every 15 minutes to make sure it is coming down. If the temperature is 40.5-41.00C, or if the temperature is not coming down you should also wet their coat with cool tap water or apply a wet towel over them while they are in front of a fan.Dogs with a temperature of greater than 41.00C should be placed in a cool swirling bath. Make sure that their head is above water at all times especially if they are very weak. Take their temperature every 15 minutes. Once it is less than 40.00C you can take them out of the bath and place a fan on them.
If your dog is collapsed, convulsing or non-responsive you shold not put them in a bath. Instead, spray their coat with cool water or cover them with a wet towel and take them to your veterinarian immediately. You should turn your car’s air conditioning to maximum or at least open the windows. You should stop all cooling measures once your dog’s temperature has come down to 39.0oC. If you continue to cool your dog there is a risk that you will make your dog too cold which can cause further damage.
Even once a dog’s temperature has returned to normal, there is the possibility for large amounts of damage to have been done. Heat stroke is a very serious condition and can cause permanent damage and can even be fatal. Often dogs with heat stroke will require treatment for several days to weeks
Fevers can also cause an elevated temperature and can be confused with heatstroke. Fevers are often caused by an infection but can occur with any condition causing inflammation or even with cancer. You should not try to cool a dog with a fever, instead you should take them to a veterinarian immediately. Fevers can occur in the absence of any of the risk factors for heatstroke. The most important way that you can try to distinguish heat stroke from fever is to identify the risk factors for heat stroke such as having been locked in a closed car or after vigorous exercise on a hot or humid day. Fevers are also rarely greater than 41oC. You should NOT use any medication such as aspirin or paracetamol to treat a dog with either a fever or heat stroke.
For more information on heatstroke and other medical emergencies, buy a copy of First Aid For Dogs
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