Dog Drinking Too Much Water: Causes of Polydipsia and What to Do

Drinking more after exercise or on a hot day is completely normal. But if your dog is constantly at the water bowl, drinking noticeably more than usual and urinating far more than before — that's polydipsia, and it warrants a vet visit.

How Much Is Normal?

A healthy dog drinks approximately 50–100 ml per kg of body weight per day. A 30 kg Labrador drinks 1.5–3 litres daily. Consistently above 100 ml/kg/day is considered polydipsia.

To measure: fill the bowl with a known amount in the morning, measure the remainder 24 hours later.

Common Causes

Diabetes Mellitus

The most important to rule out. Without sufficient insulin, glucose accumulates in blood and spills into urine, dragging water with it. The dog compensates by drinking more. Additional signs: weight loss despite a good appetite, cloudy eyes (diabetes is a leading cause of cataracts in dogs).

Chronic Kidney Disease (CKD)

Damaged kidneys can no longer concentrate urine properly. The dog loses more water and compensates by drinking. Common in older dogs. Accompanied by loss of appetite, vomiting and weight loss.

Cushing's Syndrome (Hyperadrenocorticism)

Excess cortisol causes marked polydipsia and polyuria, a pot-bellied appearance, thinning coat, lethargy and weight gain. Common in middle-aged to older dogs — especially Poodles, Boxers, and Dachshunds.

Hypercalcaemia

Elevated blood calcium (from a tumour, hyperparathyroidism or vitamin D toxicity) triggers excessive thirst.

Pyometra (Infected Uterus)

In unspayed females. The open form shows vaginal discharge; the closed form doesn't. Both cause extreme thirst. This is a surgical emergency.

Hypothyroidism

Less commonly associated with polydipsia, but possible — especially with concurrent kidney involvement.

Psychogenic Polydipsia

Drinking from boredom, anxiety or habit. Diagnosed by excluding all medical causes first.

Emergency Signs — See the Vet Today

• Extreme thirst that came on suddenly
• Urine smells sweet or fruity (diabetes)
• Unspayed female who is depressed or has vaginal discharge (pyometra)
• Dog is drinking a lot but barely urinating (possible urinary obstruction)
• Vomiting, lethargy or visible dehydration alongside increased thirst

What the Vet Will Check

• Blood panel: glucose, urea, creatinine, cortisol, calcium, T4
• Urinalysis: specific gravity, glucose, protein
• Abdominal ultrasound if pyometra, Cushing's or CKD is suspected

While You Wait for the Appointment

• Measure water intake over 2–3 days and note it down
• Observe urination frequency and volume
• Bring a fresh first-morning urine sample in a clean container
• Log everything in Purzi to have it organized before the appointment