Dehydration In Dogs: How Long Can A Dog Go Without Water

Dehydration in Dogs: Warning Signs, Causes, and When to Act

Originally written by Dan RichardsonMedically reviewed and rewritten by Janice Jones, former veterinary technicianLast updated: January 2026

Dehydration in dogs can develop quickly and, if left unaddressed, may lead to serious health complications. While most dogs drink enough water on their own, illness, heat, activity, or limited access to water can put them at risk.

If your dog has been vomiting, has diarrhea, seems unusually tired, or is exposed to warm weather, dehydration should always be on your radar. This guide explains how dehydration happens, what signs to watch for, and when home care is appropriate versus when veterinary care is essential.

How Long Can Dogs Go Without Water?

Dogs can survive short periods without water, but that does not mean they are safe or healthy.

Even mild dehydration can begin to affect circulation, digestion, kidney function, and temperature regulation. In hot weather, during illness, or after physical exertion, dehydration can progress much faster and become dangerous far sooner than many owners realize.

Any dog that goes a full day without water, especially if sick or overheated, should be closely monitored and may need veterinary evaluation.

What Causes Dehydration in Dogs?

Dehydration occurs when fluid loss exceeds fluid intake. Common causes include:

Illness

Vomiting, diarrhea, fever, and certain medical conditions cause rapid fluid loss. Dogs that feel nauseous may also avoid drinking, which worsens dehydration.

Heat and Overexertion

Warm weather, poor ventilation, excessive exercise, or prolonged exposure to hot environments increase fluid needs and accelerate dehydration.

Limited Access to Water

Empty bowls, frozen water, spilled containers, or restricted access, especially outdoors, can quickly lead to dehydration.

Pain or Mouth Discomfort

Dental disease, oral injuries, or foreign objects in the mouth may make drinking uncomfortable, causing dogs to avoid water.

Warning Signs of Dehydration in Dogs

Early recognition is critical. Signs may include:

• Reduced appetite or refusal to eat
• Lethargy or weakness
• Excessive panting
• Dry gums or sticky saliva
• Sunken or dull-looking eyes
• Reduced skin elasticity (skin stays tented when gently lifted)

Moderate to severe dehydration is a medical emergency and may also be accompanied by vomiting, diarrhea, collapse, fever, or disorientation.

Preventing Dehydration in Dogs

Most cases of dehydration are preventable with simple daily habits.

1. Ensure Constant Access to Fresh Water

Clean, fresh water should always be available — indoors and outdoors if applicable. Bowls should be cleaned daily and checked multiple times per day.

It is vitally important that your dog always has easy access to water; their water bowl should be left in a place where they can reach it.

If they spend a lot of time in the garden, their bowl should be left outside; if they are mostly indoors, it should be placed in a room where the door is always left open. Alternatively, place bowls in both locations.

Make sure that you check the level of their water at least twice a day and top it up. Every day, their bowl should be emptied out, washed with soap and water, and refilled with fresh, clean water.

2. Adjust for Heat and Activity

Dogs need more water during warm weather, exercise, and periods of excitement or stress. On walks or outings, bring water for your dog just as you would for yourself.

When the weather is hot, it is important to make sure your dog has water, as well as you.

On long walks in particular, it can be easy to forget that your dog needs a drink just as much as you do. A good rule of thumb is that when you feel like you need a drink, make sure your dog also gets one.

There are many ways you can provide water on walks.

3. Encourage Fluid Intake Through Food

Adding water to dry food or offering canned food can increase fluid intake, especially for dogs that drink poorly.

If your dog needs a bit of encouragement to drink, or if your dog has recently been sick and needs to rehydrate quickly, an easy way to get more fluid into them is to give them wet food.

You don’t need to buy any special dog food; simply add some fresh water to their food and mix it in.

If you usually feed your dog dry pellets, make sure you leave the food for at least 15 minutes to allow the pellets to absorb the water before letting your dog eat them.

4. Avoid Salty Foods

Human snacks and salty treats increase thirst and can contribute to dehydration if water intake does not keep up.

High-salt food is very bad for dogs.  Salt, whether consumed by people or dogs, can lead to excessive thirst. 

If the dog does not drink, they can become somewhat dehydrated.  Salt is also problematic because it can eventually lead to high blood pressure.  

While it is tempting to allow your dog to share your snacks, it is not a good idea.

Foods such as crisps, biscuits, bread, or popcorn contain a lot of salt, which can make your dog thirsty and, if they are not drinking enough, contribute to dehydration.

Overconsumption of salt can poison your dog and can cause vomiting, tremors, and even fits.

5. Make Sure Your Dogs Water Bowl Is Big Enough For Your Dog

It is important to ensure your dog’s water bowl is the right size. Don’t make the mistake of giving your puppy a bowl that is too big, as they are likely to step in it and spill it everywhere!

Some puppies find it hard to resist a quick swim in a large water bowl.  It is also important to ensure that bigger dogs have larger bowls, as they will obviously require more water.

Dogs typically require around 30ml of water for every pound of body weight per day. A quick bit of math (dog's weight in lbs x 30ml) will give you their daily water requirement. So, a ten-pound dog should consume about 300 ml (10 ounces) per day. 

That may seem like a lot, but consider where some of that water may be coming from.  Canned food is 70% liquid, and an ice cube treat will increase daily water intake. Hot days and exercise will increase your dog's water needs. 

To prevent dehydration in dogs, make sure the water bowl you purchase has sufficient capacity to hold enough water for at least 24 hours.  

Protect your dog from Dehydration

Preventing Dehydration in Dogs: Don’t Let Them Get Too Hot

Dogs die in cars is a mantra which is often repeated during the hot summer months and with good cause, thousands of dogs die every year from overheating. Heat stroke and dehydration in dogs is more common that we'd like to think.

In the UK the RSPCA (Royal Society for the Prevention of Cruelty to Animals) receives on average a call every two hours between June and August regarding a dog which has been left in a car.

Even when the temperature is only a pleasantly warm 70°F the temperature levels within your car can rise to 115°F in less than an hour, those sort of temperatures will definitely cause severe heat stroke and can potentially lead to death.

On hot days do not leave your dog in a car or an enclosed place which is likely to get very hot such as a conservatory.

Make sure that they are left in a well ventilated space with plenty of shade and cool fresh water to drink.

Dehydration in Dogs Due to Illness:  When to See the Vet

If your dog is vomiting, has diarrhea, refuses fluids, or shows worsening symptoms, home care alone is not enough.

Veterinarians treat dehydration using subcutaneous or intravenous fluids, depending on severity. This restores hydration safely and allows underlying conditions to be diagnosed and treated.

Mild Dehydration: Supportive Care at Home

Home care is appropriate only for mild dehydration in otherwise stable dogs who are alert and willing to drink.

Options your veterinarian may recommend include:

• Small, frequent sips of water
• Diluted, unflavored electrolyte solutions (no artificial sweeteners)
• Low-sodium broth cooled to room temperature

If your dog refuses fluids, continues vomiting, or worsens, stop home treatment and seek veterinary care immediately.

Why Dehydration Is Especially Dangerous for Small Dogs

Small dogs have less fluid reserve than larger breeds, which means dehydration can escalate more quickly. Puppies, seniors, and dogs with chronic health conditions are particularly vulnerable.

Conclusion  Dehydration in Dogs

Dehydration in dogs is common, but it is not something to ignore or “wait out.” Early recognition, prompt hydration, and knowing when to seek veterinary care can prevent serious complications.

When in doubt, always err on the side of caution and contact your veterinarian.

Author Bio:  Dehydration in Dogs

Dan Richardson is a pet blogger at milumimi.com. He has an excitable five-year-old golden retriever called Jenny and a confident four-year-old-black and white cat called Whisky, they both get on famously and of course the cat is in charge!

In his spare time he likes reading, walking the dog, cycling and playing with his one-year-old son.

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More About Janice (author and voice behind this site)

Janice Jones has lived with dogs and cats for most of her life and worked as a veterinary technician for over a decade.

She has also been a small-breed dog breeder and rescue advocate and holds academic degrees in psychology, biology, nursing, and mental health counseling.

Her work focuses on helping dog owners make informed, responsible decisions rooted in experience, education, and compassion.

When not writing, reading, or researching dog-related topics, she likes to spend time with her six Shih Tzu dogs, her husband, and her family, as well as knitting and crocheting.

She is also the voice behind Miracle Shih Tzu and Smart-Knit-Crocheting

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