Why Is My Dog Drinking So Much Water?
This article is for educational purposes only and does not promote or advertise prescription-only veterinary medicines. All treatments require assessment and prescription by a veterinary surgeon.
Excessive thirst in dogs (known medically as polydipsia) is one of the most common early signs owners notice when something may be wrong. While sometimes the cause is harmless, persistent increased drinking can also signal underlying health conditions that require veterinary assessment.
In this guide we explain:
- How much water dogs should normally drink
- Common harmless causes of increased thirst
- Medical conditions linked to excessive drinking
- When you should contact your vet
How Much Water Should a Dog Drink Normally?
Most healthy dogs drink approximately 50–60 ml of water per kilogram of body weight per day.
| Dog Weight | Typical Daily Water Intake |
|---|---|
| 5 kg dog | ~250–300 ml |
| 10 kg dog | ~500–600 ml |
| 25 kg dog | ~1.2–1.5 litres |
| 40 kg dog | ~2–2.5 litres |
Dogs may naturally drink more water if they:
- Have exercised heavily
- Are eating mostly dry food
- Live in warm environments
- Are pregnant or nursing
If your dog’s water intake suddenly increases and remains elevated for more than a few days, veterinary advice is recommended.
Common Harmless Reasons Dogs Drink More Water
Not all increases in thirst are caused by disease. Some everyday factors can temporarily increase a dog’s water consumption.
Hot Weather
Dogs regulate body temperature mainly through panting. During warm weather they may drink more water to replace fluid loss.
Exercise
After physical activity dogs often drink more water to rehydrate.
Dry Food Diets
Dogs fed dry kibble typically drink more water than those eating wet food.
However, persistent or worsening thirst should always be investigated.
Medical Causes of Excessive Drinking in Dogs
Persistent polydipsia is often associated with underlying medical conditions affecting metabolism, hormone balance, or organ function.
Diabetes Mellitus
Diabetes causes elevated blood glucose levels. Excess glucose is lost in urine, drawing water with it and leading to increased thirst.
- Increased drinking
- Increased urination
- Weight loss despite appetite
- Increased hunger
Cushing’s Disease
Cushing’s disease (hyperadrenocorticism) is a common hormonal cause of excessive thirst in dogs.
- Increased drinking and urination
- Increased appetite
- Pot-bellied appearance
- Hair thinning and skin changes
Read our guide to Cushing’s Disease →
Active ingredient: Trilostane
Trilostane may be prescribed by veterinary surgeons to help control cortisol production in dogs with Cushing’s disease. Treatment plans and monitoring schedules are tailored to the individual patient.
Kidney Disease
Reduced kidney function leads to increased urine production and compensatory thirst.
Liver Disease
Some liver conditions may alter metabolism and fluid balance.
Urinary Tract Infections
Urinary infections can increase urination frequency.
Medication Side Effects
- Corticosteroids
- Diuretics
- Some anti-seizure medications
How Vets Investigate Excessive Thirst
- Blood tests
- Urinalysis
- Urine culture
- Imaging where indicated
When Should You Contact Your Vet?
- Marked increase in drinking
- Increased urination
- Weight or appetite changes
- Lethargy
Persistent excessive thirst in dogs should always be investigated.
Managing Long-Term Conditions
If your dog is diagnosed with a chronic condition requiring ongoing treatment, your veterinary surgeon may provide a written prescription.
How to Request a Written Prescription →
Vetalia is an independent UK vet-led provider of veterinary medicines, operating in accordance with UK regulations.
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