Heat Stress and Dehydration By Dr Heather Burton – Virbac Australia
With the mercury rising over the last few weeks – especially in Queensland – it is important to check that your dogs are not getting too hot. Heat stress can occur very easily when the temperature is elevated and the humidity is high, and is an important complication that can occur during summer. The panting mechanism that dogs use to keep themselves cool is less effective when it is very humid.  So it is at these times that the dog is particularly vulnerable as it is unable to cool itself. Situations to be avoided during these very hot times are: Poorly ventilated kennels. Leaving unattended in trailers of cars – even for 5 minutes. Hydrobathing with warm water in an enclosed area. Racing or trialling a dehydrated dog. Remember that Greyhounds can lose over 200 mL of fluid per hour when panting.  Therefore any factor that causes prolonged panting can lead to dehydration.   Heat, excitement, nervousness, prolonged walking, travelling and racing can all cause dehydration in greyhounds.  It is important that this fluid that is lost during panting is replaced. Dehydration is one of the most common problems found in racing greyhounds particularly during the summer.   The signs are usually easy to recognise and include a dull, dried out coat, a slow “skin pinch” return over the neck and shoulders, a tucked up belly and passage of small volumes of concentrated urine. Dehydration can be due to loss of body fluid only, or to the loss of both fluid and body salts.  The first type is known as simple dehydration where only the fluid content of the body is depleted.  This may be due to shallow panting after exercise, traveling or to lack of drinking water.  As the fluid content of the blood decreases, the body salt concentration is increased, which stimulates the thirst response, leading to drinking if water is available and replacement of the lost fluid. The second, more serious type of dehydration is known as chronic dehydration. In this form of dehydration both fluid and body salts are depleted, preventing the thirst response from being triggered.  If electrolyte supplements are not given the greyhound is unlikely to drink sufficient water to correct its dehydration.  This form of dehydration is most common in excitable, hard walking greyhounds that pant more forcibly than normal.  It is theorised that this results in higher amounts of water loss from the lungs and an increased loss of salts, particularly potassium, from the kidneys.  Chronically dehydrated greyhounds often suffer from a loss of racing performance, poor recovery after racing and an increased risk of cramping. Some simple strategies that can be used in summer to keep our greyhounds cool are: Adequate cool Fresh drinking water. Electrolyte supplements on a daily basis and especially when traveling or racing. Ensure that all areas that the dog is in are well ventilated. This includes the car or trailer and the kennel.  Ensure that there is adequate shade in yards. Air conditioning – obviously this can be very beneficial.  It is important that air conditioning is not run 24 hours a day as this can cause the air to be dehumidified, which is not good for the dog’s respiratory system.  Simply let the air conditioner run during the hotter parts of the day and turn off for short periods of time. If a greyhound develops heat stress the following first aids tips may help. Immediately immerse the dog in cold water – straight into the bathtub with cold water (you can add bagged ice to the water to chill it quickly). Leave the dog immersed for 20-30 seconds. Wipe of excess water, dry the dog down and then repeat immersion after 2 minutes. Repeat until the body temperature drops below 40°C. If the dog is able to walk, walk it around to help increase the loss of heat from the body. If the dog is still distressed or its temperature elevated, take to your vet for assistance.