If your dog is anything like mine, they’ll sometimes seem to empty their water bowl in no time at all. That’s okay as a once-off, but if it seems to happen frequently, there might be something wrong. If you’re wondering, “Why is my dog so thirsty?” and when you should worry about excessive drinking in dogs, you’ve come to the right place.
In this article, we’ll cover what a pup’s normal thirst level should be, how to tell when they’re drinking excessively, and the main causes of excessive drinking in dogs.
Normal vs. Excessive Thirst in Dogs
Since what’s “normal” is different for different dogs, it can be hard to tell if a dog is drinking too much. Generally, normal “maintenance” water requirements are about 50 ml of water per kilogram of body weight per day – dogs should be getting that as a minimum, although moisture in food should also be taken into account.  It’s also important to note that some dogs will drink more than this, which isn’t necessarily a problem.
Some of the things that influence how much a dog normally drinks include:
- Diet (amount of moisture in food and intake of salts)
- Environmental temperature and humidity (a hot day, heating, air conditioning, etc.)
- Exercise and activity level (a working dog vs. a sedentary dog)
- Size of dog (large dogs drink a higher volume than small dogs)
- Hormones (in unneutered dogs, especially females in heat)
- Nursing pups
While larger dogs drink more water than smaller dogs in terms of volume, this is proportionate to their size. There’s no association between age, gender, or breed when it comes to the amount drunk over the course of a day, once you take the dog’s activity level and lifestyle into account.
In general, most dogs (like most humans) will drink consistently throughout the day, having a little more after a walk, when it’s hot, after they eat, or first thing in the morning. In other words, if they have free access, most dogs will visit their water bowl several times during the day, drinking “little and often;” however, it can be normal for dogs to drink less frequently if they’re sleeping or busy.
What Is Polydipsia in Dogs?
Polydipsia in dogs simply means “excessive thirst” or “excessive drinking.” It usually goes hand-in-hand with polyuria (excessive urination), either because the dog is drinking more and peeing out the excess, or because the dog is peeing more and drinking more to keep up.
Officially, polydipsia has a cutoff point of 100 ml per kilogram of bodyweight per day – any higher than this and a dog is definitely polydipsic and there’s something wrong. However, there’s a large “gray zone” where a dog’s water intake may be below 100 ml, yet they’re still polydipsic.
Why Is My Dog So Thirsty? 12 Causes to Consider
Once you know what’s normal for your dog, you can be tuned in to abnormal drinking or excessive thirst. If you’ve noticed your dog drinking more, you’ll be wondering why they’re so thirsty. There are a number of serious conditions that can cause excessive thirst in dogs. Let’s look at why your dog is so thirsty in more detail.
Pyometra is a serious infection of the uterus in unspayed females. It causes excessive thirst, excessive urination, and vomiting. Without prompt treatment, it can be fatal.
Cushing’s disease is a complex condition where a dog produces too much cortisol (a stress hormone), usually due to a benign tumor on their adrenal gland. In addition to excessive thirst, dogs with Cushing’s will urinate more than normal, eat more than normal, and gain weight, alongside developing a pot belly. It’s managed with medication but is not curable.
In older dogs, kidney disease can develop after lots of small kidney injuries add up throughout their lives. Kidney damage can also happen quickly after exposure to toxins. Either way, the kidneys become less efficient, meaning affected dogs pass more urine than they should. They then drink more to remain hydrated. It’s not curable, but diet, medication, and lifestyle changes can support the kidneys.
Dogs with liver disease may also experience excessive thirst, alongside yellow eyes and gums (jaundice), vomiting and diarrhea, or appetite changes. Unlike the kidneys, the liver can heal if given enough support and time. Medication may be needed to protect and help the healing process once the cause has been treated.
Diabetes mellitus (often just called “diabetes”) in dogs happens when dogs stop producing sufficient insulin – the molecule that helps carry glucose out of the blood and into storage. This then causes a build-up of glucose in the blood, and the kidneys try to remove the excess. Sugar in the urine “draws out” the water, meaning dogs with diabetes urinate more – and they then need to drink more to keep up. Excessive thirst is one of the key symptoms of diabetes in dogs, alongside excessive urination, weight loss, and hunger. Diabetes can be managed with insulin injections.
Not to be confused with diabetes mellitus, this is a very different disease. Diabetes insipidus is caused by the lack of antidiuretic hormone (ADH), which helps the kidneys to concentrate urine. Without this, the kidneys produce very dilute urine, which means dogs need to drink more to keep hydrated. The main symptoms of diabetes insipidus are polydipsia and polyuria, and it’s usually diagnosed after other more common causes are ruled out. The condition can be managed but not treated.
Vomiting and/or Diarrhea
Some cancers cause increased thirst, usually due to changes in biochemistry in the body. This is a rare cause of polydipsia, though, so your vet will rule out the more common causes first.
A change to a dry diet may cause increased water intake, as dogs will be getting less moisture from their food. This isn’t concerning and will eventually settle down to a new normal level.
Hotter and drier climates cause increased water intake, as dogs lose water by panting. This doesn’t just relate to outdoor conditions, however: artificial heating and air conditioning can change temperatures and humidity indoors, leading to changes in water intake.
Some medications cause thirst, most notably steroids (like prednisone) or diuretics (like furosemide). If your dog has recently started new medication and is now thirsty, you can talk to your vet about whether the medication is the cause and whether there are changes that can be made to reduce this side effect.
Exercising increases water loss, so dogs need to drink more water to rehydrate. This is coupled with the fact that most dogs don’t get the opportunity to drink while exercising. It’s normal for dogs to drink more if they’ve been exercising, whether it’s a long hike or a quick run around.
Increased Thirst in Dogs: When to Worry
Generally, temporary increased thirst is not a concern, especially if there’s an obvious cause. If your dog drinks more because they ran out of water and you’ve just filled it up, they have been for a run, or it’s a hot day and they fell asleep in the sun, that’s okay. But if the thirst lasts more than a day or two, it’s time to consider a vet visit.
If there’s no emergency (see below), it can be helpful to measure their water intake over a 24-hour period. You can do this by filling a large bowl with a known amount of water, then measuring what’s left 24 hours later. This is useful information for your veterinarian as it can help to work out whether a dog is definitely polydipsic or just drinking a bit more.
You should book a vet visit if you notice other symptoms such as:
- Urinating more, or having accidents in the house
- Vomiting or diarrhea (especially if they aren’t keeping food down)
- Weight changes
In addition, you should find an emergency clinic if your dog is:
- Panting or struggling to breathe
- Overheated (heat exhaustion)
- Unneutered and had a season in the last couple of months
- Passing blood or pus
How to Prevent Excessive Thirst in Dogs
Remember: like us, dogs need to stay hydrated. That means they should have access to water at all times. Restricting their water is not a good way to prevent dogs from drinking too much or peeing in the house, and you should instead find a veterinarian to get to the bottom of the problem. If your dog is on medication, talk to your veterinarian before restricting water.
While you’re waiting for an assessment, make sure your dog is getting plenty of water. Switching to wet food (or adding water to their dry food), providing several large water bowls around the house, or trying a water fountain may be good options.
Dog Drinking Too Much Water? What to Do
It’s possible for dogs to drink so much water in a short space of time that they get “‘water poisoning” or “water intoxication,” which is rare but can be fatal. This is usually the case for dogs who play with garden hoses or in wading pools or open water as a way to stay cool – especially if they’re smaller breeds and spend longer than 15 minutes in the water at a time. Symptoms include appearing drunk, lethargy, nausea, vomiting, and glazed eyes. This is an emergency, so you’ll need to get to your nearest veterinary clinic immediately.
Excepting this scenario, dogs don’t tend to drink too much water and will urinate out anything extra. Some people worry that their dog is drinking excessive water and urinating in the house, but remember, drinking too much is a symptom, not the cause of the excessive urination. This is why it’s important that you don’t restrict water in dogs, even if it seems to be going straight through them.
Dog Drinking a Lot of Water: FAQs
Why does my dog throw up after drinking water?
Some dogs will drink a lot of water in one go, then throw up – possibly because of the sheer volume of water in their stomach. This isn’t too concerning as long as it’s occasional, but you should ensure that your dog can keep down water – if they’re unable to do so, you need to visit the vet urgently.
If you find your dog vomiting after drinking water only occasionally, you can try to encourage them to drink more frequently so they don’t take in as much in one go – multiple bowls around the house and wetter food are two good options.
Why is my dog drinking more water than usual in winter?
If it’s winter and you notice your dog drinking lots of water suddenly, there are a couple of possible causes. If there’s been no recent change to diet, exercise, or indoor heating, you should consider measuring their water intake and calling your vet for advice. Many of the diseases that cause excessive thirst are treated more easily if caught early.
Do dogs drink a lot of water before they die?
Drinking water isn’t a sign of impending death, but many of the causes of excessive thirst can be fatal if not treated. It’s best to get excessive drinking checked out by your vet as soon as you see symptoms so your pet can get the treatment they need.
Schoeman, Johan P. “Approach to Polyuria and Polydipsia in the Dog.” (2008) Veterinary Information Network. Retrieved from: https://www.vin.com/apputil/content/defaultadv1.aspx?id=3866513&pid=11268