Dehydration in dogs: Vet's guide to signs and how to help

dehydration in dogs
(Image credit: Getty Images)

Dehydration in dogs is not a subject to be ignored. If you're a pet parent, it's important you know what to look out for when your pooch is poorly. 

After all, if you spot the signs that veterinary intervention might be needed sooner rather than later, your canine companion is more likely to make a recovery. One of the most important things to look out for is dehydration. 

But would you know how to tell if your dog was dehydrated? Let's find out what causes dehydration in dogs, what signs you might notice if your dog is dehydrated, and when to call the veterinarian.

What causes dehydration in dogs?

Dehydration occurs if your dog isn't drinking enough water to keep up with their body's needs and any ongoing losses like vomiting or diarrhea

The amount of water your dog's body needs will also be more if the weather is warm or if your canine companion is exercising. Therefore, you can see how easy it is for a dog to quickly become dehydrated, especially if they feel unwell and are not interested in eating or drinking.

What are the signs of dehydration in dogs?

If your dog is dehydrated, you might mistake them for just feeling unwell. This is because many of the symptoms of dehydration are pretty vague. For instance, if your dog is dehydrated, they're likely to withdraw and be lethargic. 

They may seem weak and just a bit miserable. However, some more specific signs can give you the information you need to decide if your dog is dehydrated. 

Firstly, if you touch their gums, they might feel dry or tacky, whereas usually, they would be moist. Second is the skin tent test. If you gently lift the skin of your dog's scruff away from their body, then drop it, you might find it's slow to return to its normal position, or even that it doesn't return. These are both signs of dehydration in dogs. 

Finally, if the dehydration is more severe, you might notice that their eyes look a little bit sunken.

dehydration in dogs

(Image credit: Getty Images)

How long can a dog last without water?

Although dogs can technically survive for around 72 hours without any water, you should always seek veterinary advice if your dog hasn’t drunk anything for 24 hours. After 24 hours, their symptoms will become more and more severe, and it could lead to permanent damage to organs like their kidneys.

How often should a dog drink water?

Dogs need to drink at least 1ml of water per kilogram of their body weight every hour. So, an average-sized Cocker Spaniel weighing around 15kg would need to drink 15ml or more of water an hour. 

Of course, this is unlikely to spread evenly throughout the day. It's much more likely that your dog will have some larger drinks and some smaller drinks, much like we do. 

What's more important is that they get their total water requirement each day. You can get some more advice by reading our guide on how much water your dog should be drinking. It's not just drinking less that is a concern with your fur friend, though; excessive thirst in dogs can also be a sign of underlying health problems. 

How do you rehydrate a dog at home?

If your dog isn't drinking as much as they should and you think they might be dehydrated, you should always visit your veterinarian. However, in the meantime, you can try to encourage drinking by flavoring the water with a small amount of cooked meat juices. Failing that, you can syringe water into their mouth or try to get them to lap water from your hands. 

dehydration in dogs

(Image credit: Getty Images)

How do you rehydrate a dog that won’t drink?

Sometimes, your dog won't drink due to nausea, pain, or feeling poorly in some other way. Dehydration can happen quickly, so it's best to get your furry family member checked over by a vet if you're worried. If your dog is dehydrated and won't drink, your vet may need to put them onto a fluid drip to get fluid directly into their circulation. 

However, if you’ve had the all-clear from a veterinarian but you're still concerned that your dog needs to drink more, why not try offering them running water from a tap or water fountain? You can find our picks of the best pet water fountains in our buying guide.  

Can dogs die from dehydration?

Sadly, dogs can die from dehydration, and it doesn't take very long. Dogs might be able to survive for 72 hours with no water, but during this time, their organs will be shutting down, and their chances of recovery will reduce. 

So, how do you know when to visit the vet when your dog might be dehydrated? Well, if your dog hasn't drunk any water for a full day, you should definitely speak to a veterinarian.


Dehydration in dogs is very serious, and it can happen very quickly. Remember that if your dog is off their food and water, or it’s a hot day, they’re more at risk of dehydration. 

This is also true if your dog has had a really active day running around, so keep lots of water available. Most importantly, you should always seek veterinary advice if it’s been 24 hours since your dog last had a drink.

Dr Hannah Godfrey is a small animal vet with a love of dentistry and soft tissue surgery. She lives in Wales with her partner, son, and their two cats.