Pete the Vet: How much water should my pet drink?

While vets don’t generally worry about pets not drinking enough, it’s a different story if an animal starts to drink excessive amounts of water. 
Pete the Vet: How much water should my pet drink?

Pete the Vet: Whippet dog drinking water.

One popular well-being tip for humans is that we should drink more water: many people force themselves to drink two or three litres of water a day in the belief that it’s good for their skin, good for their digestion, good for everything. 

I’ve yet to be convinced of the science behind the supposed benefits, but there’s no doubt that dehydration is bad for living creatures, and drinking more water is the easiest way to avoid this happening.

What about pets? Should owners try to encourage dogs and cats to drink more water? 

I’m often contacted by owners who worry that their pets are not drinking enough. Most of us can down a pint glass of fresh water ourselves, but it isn’t easy to try to force a pet to do the same. Should they be attempting this?

The answer is a definite no. 

The living body does an excellent job of ensuring that optimal hydration is continually maintained naturally. If dehydration develops for any reason, animals get thirsty. 

For healthy pets, all you need to do is to ensure that your pet has access to fresh water at all times. Their own thirst, driven by their body’s natural needs, will do the rest.

The situation is different for pets that are unwell: there are some illnesses that cause dehydration, and sick pets may not be able to drink enough to reach their optimal needs. 

Examples include severe gastroenteritis, animals in shock, and some metabolic illnesses such as unstable diabetics or pets with renal failure. Pets with these conditions that have become dehydrated will be noticeably unwell: dull, weak and inappetent. 

Any animal showing these signs should be taken to the vet urgently, and the best treatment can then be given. 

If an animal is significantly dehydrated, intravenous fluids, given as a drip into the pet’s leg, will often be recommended. This cannot be done in one big surge: the animal will usually have to be left at the vet clinic to be rehydrated over several hours or more, with the fluids given in a carefully measured amount via an electronic pump. This treatment is lifesaving for many seriously ill pets.

Oral rehydration is occasionally used when pets are less seriously ill, such as dogs with mild bouts of vomiting and diarrhoea, with electrolyte enriched fluids being dispensed. 

However, it’s still a case of gentle encouragement to drink, rather than force-feeding syringefuls of fluids. It’s too easy to cause harm. 

If a pet refuses to take fluids and struggles, the liquid can spill the wrong way at the back of the throat, then inhaled into the lungs rather than swallowed into the stomach.

It makes more sense to try to make drinking as appealing as possible, instead of using brute force. 

Multiple drinking bowls in different parts of the house, cleaned and replenished every day, can help. 

Cat fountains, with the water being recirculated continually with a small electric pump, create an impression of flowing, moving, water, which some animals seem to prefer to drink. 

Also, even simpler, try adding extra water to your pet’s feeding bowl. Dogs and cats often enjoy licking their bowls clean, and they’ll barely notice if you’ve added some extra fluid to dilute their daily meals. 

You can also buy commercially produced rehydration fluid, enhanced with chicken extracts to make it palatable to dogs and cats.

If you’re worried, it’s worth monitoring your pet’s urination: if they are passing urine regularly, then they are likely to be reasonably well hydrated. One of the key signs of dehydration is dramatically reduced urine output.

While vets don’t generally worry about pets not drinking enough, it’s a different story if an animal starts to drink excessive amounts of water. 

This is a key measurement that is often the first sign of a wide range of common diseases, from diabetes to kidney disease to a range of hormonal problems. 

There’s a well-recognised figure that vets use to judge whether or not a pet is drinking a worrying amount: 100ml per 1kg body weight. So if a 5kg cat is drinking more than 500ml, or a 20kg dog is drinking more than two litres, this is a definite sign that something is amiss.

If your pet starts to drink more than usual, measure the precise quantity, by recording how much you put into their bowl, then noting how much is left a day later. Remember that moist pet food contains significant amounts of water when you are doing these calculations.

If you discover that, yes, they are drinking too much, collect a urine sample and head down to your local vet. A blood sample is likely to be needed, and soon enough, the vet should be able to tell you why your pet is so thirsty, and what needs to be done to help them.

It’s not always easy to get that urine sample: the easiest way is to use a shallow container of some kind, following your dog around the garden, nipping in there with the receptacle at the crucial moment. 

Most dogs that are drinking more than usual are also urinating more, which at least makes this task easier. 

It’s trickier with cats: the easiest answer is to ask your vet for special glass-like beads, and to use these to replace your cat’s normal litter substrate in their tray. When they pass urine in the litter tray, this can then be drained off into a clean container to take to the vet, leaving the beads behind.

A pet’s drinking water is an important aspect of their life, and for the sake of your pet’s health, it’s worth monitoring this carefully.

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