Your Cat Is Drinking More: Why That Matters

Cats evolved from desert animals and are built to get most of their water from prey. A cat that starts drinking noticeably more is telling you something, and it is usually one of three things.

The three big causes

• Chronic kidney disease. Very common in older cats. The kidneys lose the ability to concentrate urine, so the cat produces more and drinks more to compensate. Often accompanied by weight loss, poor coat and reduced appetite.
• Diabetes. Excess glucose pulls water into the urine. Often accompanied by increased appetite alongside weight loss.
• Hyperthyroidism. Common in older cats. Increased thirst plus a big appetite, weight loss, restlessness and sometimes vomiting.

Urinary infections, liver disease and some medications also increase thirst.

How to measure it

Impressions are unreliable, so do this properly for two or three days. Use a single measured water source, note how much you put in, and measure what is left after 24 hours, accounting for evaporation with an identical bowl in the same room that the cat cannot reach.

As a rough guide, a cat drinking substantially more than about 50ml per kilogram of body weight per day is drinking too much. A 4kg cat drinking more than roughly 200ml a day warrants investigation. Cats on dry food drink more than cats on wet food, so factor that in.

Also watch the litter box

Larger or more numerous clumps mean more urine, which usually means more drinking. Litter box changes are often noticed before drinking changes.

What to do

Book a vet appointment and mention the measurement specifically. Expect blood tests and a urine sample — bring one if you can, using non-absorbent litter or a clean empty tray. Most of these conditions are far more manageable when caught early, and kidney disease in particular is diagnosed late in a great many cats simply because nobody noticed the drinking.

The counterpart

A cat that suddenly stops drinking, or a male cat straining in the litter box producing nothing, is a same-day emergency. Urinary blockage kills within a day or two and it is one of the most time-critical conditions in feline medicine.