- Excessive drinking (polydipsia) can be a warning sign
- Possible causes: diabetes, kidney problems, Cushing's syndrome
- Rule of thumb: more than 100 ml per kg of body weight/day is unusual
More than 100 ml of water per kilogram of body weight per day counts as an elevated water need. Harmless causes like heat or physical activity are common. If the increased thirst lasts several days or other symptoms appear, a vet needs to find the cause.
How much water does a dog need?
The water requirement depends on body weight, food, activity, and outside temperature. Guideline values at normal activity and 20–24 °C:
| Type of feeding | Water need per kg of body weight/day |
|---|---|
| Dry food | 50–100 ml |
| Wet food | 20–50 ml |
Example: a 32 kg dog on dry food needs 1,600–3,200 ml of water per day. Every dog has an individual need: these figures are meant as a guide. Fresh water always has to be available in sufficient amounts.
Polydipsia and polyuria
When a dog drinks and urinates noticeably more than usual, veterinary medicine distinguishes two terms:
- Polydipsia: Increased thirst as the trigger for the increased urge to urinate
- Polyuria: Increased urge to urinate as the trigger for the increased thirst: more common
Temporarily increased drinking during heat, exercise, or stress is normal. If the increased need lasts several days or the following signs appear, see a vet:
- More frequent, lengthy urination
- Pain while urinating
- Dog no longer house-trained
Common medical causes
Diabetes
A metabolic disease that usually shows up in the second half of life. Missing or ineffective insulin can't carry glucose into the cells: blood sugar rises. The sugar molecules pass into the urine and pull water out of the body, which increases both the urge to urinate and thirst.
Bladder infection
Often caused by bacteria. Accompanying symptoms: a stronger urge to urinate but only a few drops of urine, pain while urinating, a changed urine color or smell, occasionally blood in the urine. More on this: Bladder infection in dogs.
Kidney disease
Diseased kidneys can no longer concentrate urine: more urine is passed and thirst rises. The urine is often pale and clear. In acute cases, treatment with antibiotics (e.g. against leptospira).
Uterine infection
Usually appears about a week after the heat cycle: more common in older female dogs. Bacteria reach the uterus through the still-open cervix. Left untreated, it can lead to blood poisoning, fever, or shock.
Cushing's syndrome
The adrenal gland produces too much cortisol. Typical accompanying symptoms besides the increased thirst: hair loss on the trunk, thin skin, a sagging belly (potbelly), muscle weakness. It mainly affects older dogs of medium and small breeds. Diagnosis is made through blood tests, treatment with medication (Vetoryl/trilostane).
Medications as a trigger
Cortisone (prednisolone), diuretics (furosemide), and some epilepsy medications (phenobarbital) raise thirst considerably. If you notice your dog is on these medications and at the same time see increased thirst: this is a known side effect and no reason to panic. Bring it up with your vet at the next check-up.
Measuring how much your dog drinks
To measure the actual water need: each day, use a measuring cup to note how much water you refill, then subtract the leftover amount after 24 hours. Measure on three normal routine days: not during heat, intense exercise, or a change of food. Bring the result (ml/kg body weight/day) to your vet. A form for determining the water need is available to download.
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Question 1 of 3At what value is a dog's water need considered elevated?
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