Why Is My Dog Drinking So Much Water?

Normal water intake for dogs is roughly 1 ounce per pound of body weight per day (about 60 ml/kg). A 50-pound dog normally drinks about 50 ounces (6+ cups) daily. However, this varies with temperature, activity level, diet (dry kibble requires more water than wet food), and individual variation.

Polydipsia — abnormally increased thirst — is defined as consistently drinking more than 80-100 ml/kg/day. It's often paired with polyuria (increased urination), and together they're one of the most common reasons for veterinary visits in middle-aged and older dogs.

The most common medical causes are: diabetes mellitus (blood sugar spills into urine, pulling water with it), kidney disease (kidneys lose ability to concentrate urine), Cushing's disease (excess cortisol increases thirst), and urinary tract infections (irritation triggers the urge to flush the bladder). In intact (not spayed) females, pyometra (uterine infection) is a life-threatening cause of sudden increased thirst.

Medications are another common cause — steroids (prednisone) and some seizure medications dramatically increase thirst and urination. If your dog recently started a new medication and is drinking more, this may be an expected side effect.

To help your vet diagnose the cause, try to quantify your dog's water intake for a few days: measure water into the bowl, measure what's left after 24 hours. This information is extremely helpful for diagnosis.