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Why Is My Dog Drinking Excessive Amounts Of Water?

Written by Ella White


dog having a slurp of water

All dogs need to drink plenty of water throughout the day. But if you notice your pup is excessively thirsty and drinking much more water than usual, it could be a sign of something bigger. So if you’ve noticed that you keep having to refill their water bowl, and they’re drinking huge amounts in one go, it could be polydipsia – the medical name for excessive thirst in dogs.

But what makes a dog drink too much water? What is a normal amount of water for dogs to drink each day? And what are the causes of polydipsia in dogs?

In this blog, we’ll look at the potential causes, symptoms, and treatments that dog owners should be aware of if they notice their pet drinking excessive water.

Why is My Dog Drinking So Much?

Polydipsia, or drinking more water than usual, is not an issue in itself. But it is often a symptom of a larger problem. Dogs that are drinking more water could have just participated in more activity than usual, be suffering from overheating in warm weather, recovering from an illness that has dehydrated them like vomiting or diarrhea, or they could have an underlying issue that’s making them excessively thirsty.

Illnesses That Cause Dogs To Drink Excessive Water

To understand whether your dog is drinking more water than usual – and how much more – it’s important to have a good understanding of how much water your dog drinks on a normal day. The general rule of thumb for this is 1 oz per 1 lb of body weight. So if your dog weighs 20 lbs, they should be drinking around 20 fl oz of water daily.

Drinking much more than this could be a symptom of a disease or condition, including:

  • Dehydration
  • Diarrhea and vomiting
  • Cushing’s disease
  • Liver disease
  • Diabetes 
  • Cancer
  • Infection
  • Fever
  • Response to medications
  • Hormonal diseases
  • Heatstroke or hyperthermia
  • Electrolyte levels
  • Hyperthyroidism
  • Parasites
  • Hypercalcemia


One of the most common reasons that dogs start to drink more water than normal is because they’re dehydrated. Like humans, dogs can easily become dehydrated following excessive activity or exercise, illness, or hot days in summer.

Dehydration in dogs is extremely serious and can be fatal. So it’s important that they always have access to enough water – especially in hot weather. Other symptoms of dehydration include a dry mouth with thick saliva, and excessive tiredness.

When a dehydrated dog does have access to water they can easily drink too much, which can make them vomit. So make sure they do not have access to more than their normal daily intake of water at any time.

Cushing's disease

Cushing’s disease/learn/dog-health/cushings-disease-in-dogs-the-symptoms is a hormonal condition caused by a pituitary or adrenal tumor which leads to excessive excretion of cortisol. This makes dogs excessively thirsty and in turn, they urinate excessively too. 

Cushing’s disease is most common in older dogs, and comes with other symptoms including weakness, lethargy, and muscle loss. If you think your dog has Cushing’s, a vet will be able to diagnose the disease and prescribe either medication or surgery as treatment.

Diarrhea and/or vomiting

Because diarrhea and vomiting lead to excessive fluid loss, dogs will often drink lots of water after their illness. This is a normal way to prevent dehydration and to recover from whatever condition was causing their diarrhea and vomiting. 


Dogs can develop diabetes just like humans. It’s a result of insulin deficiency or resistance, and it leads to spikes in blood sugar excreted by the kidneys. Though diabetes can’t be cured, dogs suffering with the condition can be put on lifelong treatment plans to manage the symptoms – one of which is excessive thirst.

This is because diabetes can lead to excessive urination, which dogs then need to make up for by drinking more water. If you think your diabetic dog is drinking excessive amounts of water, speak to your vet about reviewing their diet plan and insulin intake.


Some dogs can develop excessive thirst as a result of a dry food diet. Because some dry foods contain as little as 5% water, dogs on these diets will often drink more water to make up for the lack of it in their meals.

Similarly, dogs that eat too much sodium, as this causes excessive thirst just like it does for humans after a particularly salty meal. High-sodium foods and ingredients should be avoided in dog’s diets as they can lead to other issues like sodium poisoning.

Kidney Disease

Because urine is created in the kidney, dogs suffering from kidney disease might be unable to produce concentrated urine – where the kidneys remove excess waste and water before the urine travels to the bladder. This leads to more frequent urination, and as a result, excessive water consumption. 

It’s important to see a vet if you notice changes to your dog’s toilet and drinking habits, so they can diagnose (or rule out) kidney stones, kidney disease, or kidney failure. 


Excessive thirst is a side effect of some dog medication, including prednisone, furosemide, and phenobarbital. If your dog is on any medications for seizures, heart conditions, or anti-inflammatories, they could cause your dog to drink more water than usual.

If you think this is the reason for your dog’s excessive drinking, it’s still worth confirming this with your vet, who will check for other causes that can hopefully be ruled out.


Female dogs that have not been spayed can suffer from an infected uterus, known as pyometra. If your female dog is drinking more than usual, eating less, and also seems lethargic and depressed, they may be suffering with pyometra.

If you think this is the case, seek veterinary attention immediately as untreated pyometra can be life-threatening.

Do I Need To See A Vet About My Dog Drinking Excessive Water?

Whether you suspect your dog is dehydrated or has an underlying disease, it’s always best to make an appointment with your vet to check whether their excessive drinking needs to be treated. 

Before you go to the vets, do not take your dog’s water away from them. If they are dehydrated for any reason, their excessive water drinking could be a necessary response to their illness. 

In some cases, vets may want a urine sample, and they are likely to ask about any changes to your pet’s diet, activity levels, and living environment. To diagnose or rule out any of the aforementioned causes of polydipsia, your vet will probably carry out a physical exam and possibly blood and urine tests to check their kidney and liver functions. These tests can also help identify any other underlying causes of your dog’s excessive thirst.

How Can I Manage My Dog’s Water Consumption?

When you first bring a dog home, one of the most important things you should know about their care is how much they need to eat and drink each day. This will help you identify any changes that might occur in their routine, and respond faster to these changes that could indicate a medical condition.

Filling your dog’s water bowl at the same time and to the same level every day, and noticing how much – if any – is left when you refresh it, is an easy way to keep track of how much water they usually drink. Then, if that level drops or increases dramatically, you’ll know straight away and can decide whether you feel they need medical attention.