Drinking and urinating more than usual is one of the most important early warning signs in pets — it's how kidney disease, diabetes, and several hormonal conditions first announce themselves.
Written or medically reviewed by Dr. Susset Diaz Castillo, DVM, PhD.
Quick Summary: Drinking and urinating more than usual is one of the most important early warning signs in pets — it's how kidney disease, diabetes, and several hormonal conditions first announce themselves.
Polyuria/polydipsia (PU/PD) means a pet is drinking and urinating substantially more than normal — typically more than 100 ml of water per kilogram of body weight per day. It is one of the most important early warning signs in veterinary medicine, commonly pointing to kidney disease, diabetes, or hormonal conditions long before pets appear visibly sick.
In-Home Veterinary Note: Measuring true water intake is far easier at home than in a clinic. During an in-home visit in Miami-Dade County we can quantify drinking, collect a urine sample, and run bloodwork in one low-stress appointment.
Increased thirst (polydipsia) and increased urination (polyuria) almost always travel together, and they are among the most medically meaningful changes an owner can notice. Unlike many vague symptoms, they usually point to a short list of important, testable conditions — and nearly all of them do better with early diagnosis.
As a rule of thumb, drinking more than about 100 ml per kilogram of body weight per day (roughly 1.5 cups per 10 lbs) is abnormal. In practice, families notice it indirectly: refilling the bowl more often, a dog asking to go out at night, a cat's litter clumps getting dramatically bigger, or accidents in a previously house-trained pet.
This is not a monitor-at-home symptom. Any sustained increase in drinking or urination lasting more than a few days deserves testing — the causes are essentially all conditions where early treatment changes the outcome. Bring useful data if you can: measure the water actually consumed over 24 hours before the visit.
The workup is straightforward and high-yield: bloodwork plus urinalysis together — the urine concentration is the key that unlocks the blood values, so both are needed. Depending on results we may add thyroid testing, blood pressure measurement, urine culture, or abdominal ultrasound to look directly at the kidneys, adrenal glands, bladder, and uterus. All of this can be done in your home, which matters because stress-free urine samples and calm blood pressure readings are genuinely more accurate.
Entirely cause-dependent: kidney-support diets and fluid plans for kidney disease, insulin for diabetes, medication or other therapy for thyroid and adrenal disease, antibiotics for infection, surgery for pyometra. The common thread: caught early, most of these conditions are managed for years of good quality life. Never restrict water to reduce accidents — pets with these conditions need every drop they're asking for.
A rough guide is 20–70 ml per kilogram of body weight daily — for a 10 lb cat, that's about ½ to 1½ cups; for a 50 lb dog, roughly 2–7 cups depending on diet, weather, and activity. Consistently exceeding about 100 ml/kg/day is medically abnormal. Wet-food diets lower drinking substantially, so a canned-fed cat who starts visiting the water bowl regularly is notable even at 'normal' volumes.
Yes — this is exactly the scenario where testing pays off most. In senior cats, increased thirst is very often the first and only sign of early chronic kidney disease or hyperthyroidism, both of which are far better managed when started early. Waiting for weight loss or vomiting means waiting for a later disease stage.
Hot weather and activity do increase drinking temporarily, and that's normal. The distinguishing features of a medical cause are persistence (continuing regardless of weather, day after day), nighttime urination, accidents in the house, and larger litter clumps. If the change lasts more than a few days or comes with any appetite or weight change, test rather than assume.
Dr. Susset Diaz Castillo, DVM, PhD is a licensed veterinarian and the founder of VestaSoul — My Vet At Home®, a mobile house-call veterinary practice providing comprehensive, low-stress care to pets across Miami-Dade County. Learn more at Meet the Vet.
VestaSoul — My Vet At Home®, also known as My Vet At Home, is a mobile veterinary house-call practice serving dogs and cats in Miami-Dade County. Led by our Chief Veterinarian, the practice provides in-home veterinary visits, wellness exams, vaccines, diagnostics, pet travel health certificates, senior pet care, and integrative veterinary medicine.