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Heat Stress & Heat Stroke

When summer arrives people are told to stay in the cool, drink lots of fluids, and avoid exercising in the heat of the day.  Despite our best efforts, people still tend to be affected, whether by dehydration, lack of sleep, or reduced appetite. But what affect does summer heat have on greyhounds, and what can we do to help them best cope?

 

Heat Stress & Heat Stroke

 
Keeping Cool
Probably the biggest difference between us and greyhounds is the different ways in which our bodies work to maintain a stable operating temperature.  For humans, body sweat is used to cool our skin, but greyhounds can’t sweat all over like we do, instead only sweating through glands on the pads of their feet and nose.  Greyhounds instead rely on evaporative cooling from their respiratory system – panting to move air across wet membranes.

This system of cooling has limitations and has important consequences for the greyhound.  Firstly, the evaporation can only occur if the humidity in the air allows it – the higher the humidity the less this system works.  So when in a confined space such as a car, trailer or kennel, humidity can increase quickly as evaporated water from the greyhound stays in the air.

The second problem with this sort of cooling is that it can lead to huge losses of body fluids and can alter the acid-base balance in the dog’s blood from the increased amount of oxygen-carbon dioxide exchange in the lungs.  These changes are hard to measure because you may not be able to actually see them.

 
What will you see?
Heat Stress – panting, salivating, increased heart rate, listlessness, vocalisation/whining

Heat Stroke – excessive or loud panting, thick saliva, vomiting, diarrhoea, wobbliness, strange behaviour, seizures, collapse, and death

 
What can you do?

  • Stop all exercise
  • Move to a shaded area or, ideally, into an air-conditioned area
  • Provide plenty of cool, fresh water
  • Provide plenty of ventilation to move evaporated fluid away and to drop the humidity levels
  • Gently cool the greyhound – they can lay on wet towels, be wiped down or hosed with cool water.  Make sure if you are using wet towels or ‘Cooling Coats’ that they feel cool to touch and that there is a breeze or ventilation as these methods rely on evaporation for their cooling effects too – if they dry out or there is no ventilation then it’s similar to wearing a blanket or rug.
  • Avoid using iced water on the greyhound’s body as this can cause the blood vessels in the skin to contract, which will slow the cooling process down because the hot blood is no longer coming to the surface where it can lose heat.  Iced water can be used on the feet though, and covered ice packs can be placed in between the dog’s thighs and in their ‘arm-pits’.

 
What if I think a greyhound is moving into heat stroke?
Heat stroke is more serious as there can be delayed complications due to organ damage.  The priority is to lower the body temperature quickly, but care has to be taken not to cause hypothermia (too cold) in the process.  Any dog with a rectal temperature over 41.6 degrees is considered dangerously hot.

These dogs need to be taken to the vet immediately, where cold intravenous fluids and cool water enemas can be done.  The vet can also monitor for complications and give medications to aid in preventing some of the consequences of a body temperature that’s too high – such as brain swelling and shock.

 

 
Kennel Design and Monitoring of Greyhounds on Hot Days
Obviously the way a greyhound is housed has a huge effect on how it copes with hot weather.

If you have facilities with indoor areas, you need to think about insulation and ventilation.  While a metal/tin garage or shed provides shade, it might restrict air flow, and if it’s not well insulated, it might end up being hotter inside than outside.  If your kennels are not set up for extreme heat – such as not having air conditioning – you need to have alternate strategies for hot days, because there is no excuse for letting your dogs suffer from heat stress or stroke.  You might think about moving the dogs off-site or leaving them outside if there is adequate shade in the runs and the areas are adequately fenced.

If you only have a few greyhounds, you could bring the dogs inside your house.  Hot dogs are generally less active than usual, so most will settle on some tiles or in front of a fan.  If it is too hot outside or in the kennels for you – then it’s too hot for the greyhounds!

Regular checks are vital to ensure that all greyhounds in your care are coping in the heat, and that they all have access to shade and plenty of cool, fresh water.  Water containers need to be such that they cannot be accidentally tipped or spilled by the dog.

If you keep your greyhounds at kennel facilities that are not at your house, you must take the time to go and inspect them regularly in hot weather.

 
Transport, Training and Racing in Hot Weather
Avoid transporting your greyhounds in the heat of the day if at all possible, but if you must, make sure ventilation is at a maximum, and that your transport vehicle has been cooled as much as possible before the greyhounds get in.  Place the trailer or car in the shade, open the windows and doors and start the air-conditioning well before you travel.  You can also use wet towels, ice in open containers, and so on, to lower the temperature where the greyhound will be.

GRV’s hot weather policy travel guidelines state that on days when the forecast temperature is predicted to be 32 degrees or above, trainers are expected to only transport greyhounds to racetracks in air-conditioned transport facilities.

Because exercise significantly increases fluid loss and raises body temperature, it is best it’s not done unless early in the morning when it’s cooler.  It may be that your training and trialling schedule for each dog is altered to allow days off when it’s hot.  Although this may seem like a step backward in terms of maintaining fitness, the damage that could be done from even one run in extreme heat may be worse than giving your dog a day off.

GRV has a Hot Weather Policy that allows you to scratch your greyhounds if it’s predicted to be hot, and you can always choose not to nominate your greyhounds if the weather for the day of the race meeting is predicted to be extreme.

If you do choose to run your greyhounds, make sure that they drink plenty of fluids BEFORE racing, as well as afterwards.  Reluctant drinkers can be encouraged to drink by flavouring the water, either with a splash of milk (lactose-free milk is best), or with something like a stock cube.  There are also electrolyte mixes that can be added to the water, but don’t overdo it as too much electrolyte can actually cause increased dehydration.

When your dog returns from a run, pay particular attention to cooling it down – the dog should have stopped panting before it is returned to the kennels or trailer.  Don’t simply hose it off and put it back into the stationary trailer whilst you run another dog.  This applies to your greyhounds after a run in the yards at home too, as elevated body temperature can occur quickly, especially if dogs are running up and down the fences with each other.

Finally, monitor your greyhounds closely for the longer-term effects of hot weather.  You need to be watching food intake, water intake, body weight, coat condition and elasticity, and you may even need to monitor blood levels of electrolytes.  Contact your greyhound veterinarian for advice if needed.

 

For more information about Greyhound Care and Standards, click here.