My Dog Is Drinking Too Much Water — A Guide to Suspecting Diabetes, Kidney Disease, and Cushing’s Syndrome

EndocrineSymptomsMeongsiljang Veterinary Advisory Board

We’ve compiled the accompanying symptoms of diabetes, chronic kidney disease, and Cushing’s syndrome to watch for when your dog suddenly starts drinking excessive amounts of water, along with the emergency criteria that warrant an immediate trip to the vet.

When Your Dog Drinks Too Much Water — Assess Urgency First

A pet owner observing their dog’s water intake.

Polydipsia in dogs is defined as drinking more than 100 ml of water per kilogram of body weight in a 24-hour period, and it can be a sign of endocrine or kidney diseases such as diabetes mellitus, chronic kidney failure, or Cushing’s syndrome. The most important step is to objectively measure whether your dog’s water intake has increased by 1.5 to 2 times or more compared to their usual amount. If polydipsia is accompanied by polyuria (increased urine output) or if your dog is losing weight despite maintaining a normal appetite, it is likely pathological polydipsia rather than simple thirst, and you should seek prompt veterinary examination.

Normal Water Intake by Weight vs. Polydipsia Criteria

Item	Normal	Borderline (Monitor)	Further Diagnosis
24-hour Water Intake per 1kg Body Weight	50–80ml	80–100ml	Over 100ml
Conversion for 5kg Dog	250–400ml	400–500ml	Over 500ml
Conversion for 10kg Dog	500–800ml	800–1000ml	Over 1000ml
Recommended Action	Routine care	Record water intake for 1 week	Immediate clinic examination

A dry-food-based diet naturally involves more water intake than a wet-food diet. For the first 1–2 weeks right after changing food type, regard it as within the normal range of fluctuation and monitor.

Checklist of Accompanying Symptoms to Suspect Pathological Polydipsia

To determine whether these symptoms indicate an underlying disease or are merely temporary, it is essential to observe accompanying signs. - Polyuria (increased urine volume): A key indicator is an increased frequency of urination during walks or sudden indoor accidents. - Weight loss: If your pet is losing weight despite maintaining a normal appetite, diabetes should be the primary suspicion. - Pot-bellied appearance: A distended abdomen combined with a thin waistline suggests Cushing’s syndrome. - Symmetrical hair loss: Hair loss occurring in identical locations on both sides of the body signals a hormonal imbalance. - Lethargy: Refusal to go for walks or increased sleepiness may indicate the progression of kidney failure or diabetes.

The abdominal sagging and symmetrical hair loss seen in Cushing's disease

Signs That Require an Immediate Trip to the Emergency Vet

If your pet has been vomiting and unable to keep down anything except water for more than 24 hours, if their breathing becomes abnormally rapid and their breath smells sweet (like acetone), or if they show signs of lethargy, seizures, or an inability to stand, you must take them to a 24-hour emergency veterinary clinic immediately. Uncontrolled diabetes can lead to a buildup of ketones in the body and metabolic acidosis, resulting in diabetic ketoacidosis (DKA), which is a critical condition requiring urgent emergency treatment. If you notice any of these signs, do not delay; getting your pet to a vet right away is the safest course of action.

Cause 1 — Canine Diabetes

Canine diabetes is a metabolic disorder caused by insufficient insulin secretion from the pancreas, leading to blood glucose levels exceeding the normal range. The excess glucose in the blood is excreted in the urine, drawing water along with it due to osmotic pressure. As persistent hyperglycemia develops and glucose begins to appear in the urine (glycosuria), polydipsia (increased thirst) and polyuria (increased urination) occur simultaneously. Veterinary textbooks define polydipsia, polyuria, polyphagia (increased appetite), and weight loss as the hallmark symptoms of diabetes. Diagnosis is confirmed by identifying both persistent hyperglycemia and glucosuria, while tests such as fructosamine are used as adjunctive tools to assess average blood glucose levels over time. The cornerstone of treatment is stabilizing blood glucose levels through insulin therapy.

Cause 2 — Chronic Kidney Disease

Chronic kidney disease is a condition in which the kidneys’ filtering and reabsorption (urine-concentrating) functions gradually decline, leading to the production of large volumes of dilute urine and increased water intake to compensate for fluid loss. In the early stages, there are often no obvious symptoms beyond excessive thirst and urination, so the condition is frequently detected late. As it progresses, weight loss, dehydration, and vomiting may occur. Blood tests reveal azotemia, characterized by elevated blood urea nitrogen (BUN) and creatinine levels, and a reduced ability to concentrate urine, with specific gravity dropping to the isosthenuric range (1.008–1.012), indicating impaired kidney function. The earlier the diagnosis, the more effectively disease progression can be slowed through targeted treatments such as dietary management and fluid therapy.

Ultrasound examination of a senior dog's kidneys

Cause 3 — Cushing’s Syndrome (Hyperadrenocorticism)

Cushing’s syndrome (hyperadrenocorticism) is an endocrine disorder caused by excessive cortisol (glucocorticoid) activity, leading to symptoms such as increased thirst and urination, a distended abdomen (“pot-belly”), symmetrical hair loss on both sides of the body, and increased panting. In most cases (about 85%), it is pituitary-dependent, where the pituitary gland overproduces ACTH, stimulating both adrenal glands. In about 15% of cases, it is adrenal-dependent, where a tumor on one adrenal gland secretes cortisol. Because baseline cortisol levels fluctuate significantly, a standard blood test alone is insufficient for diagnosis; definitive diagnosis requires dynamic testing, such as an ACTH stimulation test or a low-dose dexamethasone suppression test. The condition has been reported in breeds such as Yorkshire Terriers. Treatment typically involves lifelong medication to suppress cortisol activity, tailored to the underlying cause and form of the disease.

These Cases Are Temporary and Normal

Drinking a large amount of water for about 30 minutes to an hour after exposure to summer heat above 30°C (86°F), or immediately after walks and play, is a normal physiological response. Similarly, a temporary increase in water intake is natural during the first 1–2 weeks after switching to a drier dry food, or for several hours after consuming salty treats. However, if your pet continues to drink more than twice their usual amount for over a week even in a cool environment, or if they start seeking water in the early morning hours, this pattern should be considered indicative of an underlying medical condition.

Measuring and Managing Water Intake at Home

If you suspect pathological polydipsia, accurately measure your pet’s 24-hour water intake at home. Weigh the empty bowl, add a known volume of water (e.g., 1000 ml), and subtract the remaining amount after 24 hours to determine the actual intake. Also, keep a record of urination frequency, urine color, and the frequency of accidents, as this information will significantly speed up diagnosis during the veterinary visit. Never restrict water intake arbitrarily. Polydipsia is a compensatory response to prevent dehydration; forcing a reduction can rapidly worsen renal failure or shock. For detailed guidance on insulin schedules and dietary management, refer to the Dog Diabetes Management Guide.

How to measure your dog’s 24-hour water intake

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

How much water intake per day is considered abnormal?

If a dog drinks more than 100 ml of water per kilogram of body weight in 24 hours, it is considered polydipsia (excessive thirst). Some textbooks use 90 ml/kg as the threshold. If a 5 kg dog drinks over 500 ml in a day, or a 10 kg dog drinks over 1 liter, it is a sign that a veterinary check-up is needed.

We switched our pet’s food from dry kibble to wet food, and now they’re drinking less water. Is this normal?

Yes, this can be normal. Wet food has a high moisture content, so pets consume water along with their meals, which may naturally reduce the amount of water they drink from their bowl compared to when they eat dry food. When you first switch food types, it’s a good idea to monitor their water intake for about 1 to 2 weeks and consider any changes as normal fluctuations.

What tests will my pet undergo at the clinic if they show these symptoms?

We start with a standard blood test, biochemistry panel, and urinalysis. These tests alone can screen for diabetes, kidney dysfunction, and Cushing’s disease. Depending on the results, further specialized tests such as an ACTH stimulation test (for Cushing’s), fructosamine (for diabetes), or a renal ultrasound (for kidney failure) may be necessary.

Can diabetes and Cushing’s disease occur at the same time?

Yes, they can occur together. Excess cortisol causes insulin resistance, making blood sugar control difficult, so dogs with Cushing’s disease may also be diagnosed with diabetes. When both conditions are present, adjusting insulin dosage can be challenging, so consultation with a specialist is recommended.

My senior dog is drinking slightly more water than usual. Is it okay to just leave it as is?

If your senior dog is drinking more water than usual, it’s wise to first consider the possibility of early-stage kidney disease. The earlier kidney disease is detected, the better we can slow its progression, so even if the change seems minor, it’s safest to have a routine blood and urine test done.