Dog Behaviour

Sue Gilmore MA FCFBA

Dehydration in Dogs

How to keep your dog happy and healthy

The need to have water always available to your cannot be underestimated. This brief article is intended to draw attention to some of the problems that can be caused by dehydration and how simple it is to avoid them.

The body mass of dogs, like humans, is approximately 80% water. Water is essential to sustain life. It allows substances to dissolve and pass through the body; it is fundamental to virtually all the processes and chemical reactions that enable the body to function, including digestion, circulation and elimination. Water regulates body temperature through evaporation – without it serious problems may occur, including kidney and heart damage.

So how much water does a dog need? As a rough guide an 18 kilo dog would need approximately one litre of water per day. Environmental factors, level of activity and the health condition of your dog all inform the amount of water he requires on a daily basis. Dogs have sweat glands only on the nose and foot pads, which make heat dissipation quite inefficient in comparison to the human body. Dogs pant to cool themselves, stretch out on cool surfaces and seek shade in warm weather to alleviate feeling uncomfortably hot. Leave a clean bowl of water down for your dog so that he has access to it at all times and instantly you take the worry away. Dogs are great at knowing what they need, after all, their survival instincts inform their natural behaviour, for example, they eat grass to purge their intestines and nibble at selected herbs and plants in the garden to obtain nutrients that may be missing from their diets.


How do you recognize signs of dehydration? Your dog may become lethargic, have dry pale gums, constantly lick his lips or have sunken eyes; have an increased heart rate; loss of skin elasticity, for example. Give small amounts of water every few minutes. A trip to the vet in such circumstances is probably the best course of action and he may give intravenous fluids, but perhaps of equal importance, find the cause of the problem.

One of the main causes of dehydration is feeding dogs kibble food – most popular brands are kibble sprayed with oils etc., to make them smell appealing to dogs. Here’s a test you can try: measure out a cup of dog food and half-fill a bowl with water, leave for an hour or so and see just how much water has been absorbed. Now, imagine your dog eating the kibble (dry) and, in order for his food to be digested, estimate how much body fluid is required to rehydrate the food. You get the picture and understand the need for fresh water to be always available. Just for fun, try eating two dry cream crackers (maybe one will be enough!) and not having any water available to rinse your mouth….

Dogs at risk of dehydration include older dogs, pregnant or nursing dogs, puppies, those who are ill, have diarrhoea or are vomiting, dogs without access to water or have dark coats, for example.

Prevention is better than cure (and it’s cheaper!). Ensure that your dog has access at all times to fresh water in a bowl that cannot be tipped over easily. Take plenty of water along with you when you are travelling and offer it to your dog at regular intervals, especially if you are working your dog in outdoor activities. Some dogs refuse to drink, but it may be worth checking that he has no obstruction causing him to be unable to drink. When in doubt, consult your vet.


Following the appalling news that two dogs were baked alive in a police dog handler’s car recently – the second time that this particular officer has left his dogs in a secure car without ventilation in very hot weather – it cannot be emphasized enough that if dogs are left in vehicles without adequate ventilation, a supply of water, shade and also the ability to move around to avoid direct sunlight, the consequences are obvious. Perhaps this is blindingly obvious to us as responsible dog owners, but, following a brief question and answer session with some members of my puppy class recently, they thought it was OK to leave puppy in the car unattended whilst they went into a supermarket, or whilst mum waited to collect the children from school or other activities, provided that it was for only a short time.

The police dogs mentioned above, one a puppy German Shepherd, perished within a comparatively short period during and that was before midday when the summer heat would obviously intensify. Try this: when you next reach your destination, turn the air conditioning off and wait in your car for one minute with the windows closed in full sunshine. You will stifle, but just imagine being powerless to open the door and get out, or even open a window and you will know what I mean. I now have a brief chat about dogs in hot weather during all my classes and on all behavioural visits, because what I think is basic dog care (and common sense) clearly does not cross some owners’ minds….

Sue Gilmore

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