Increased thirst is called polydipsia and increased urination is called polyuria in technical terms.
Increased thirst is a relatively common symptom in older cats. Thirst is usually due to increased urine production, ie too much fluid than normal leaves the body. The cat must then drink more to compensate for the fluid loss. What the owner usually sees is that the cat drinks more than normal, as many cats fulfill their needs outdoors.
Cats normally drink about 20 – 50 ml of fluid in total per kg and day. Consideration must be given to the type of food the cat eats, as for example a cat that only receives dry food drinks more than the cat that only receives wet food.
Chronic kidney disease, diabetes, and hypothyroidism (hyperthyroidism, sometimes called toxic goiter) are the most common causes of increased thirst in cats. Other reasons may be changes in fluid and salt balance or side effects of medications.
To find out the cause of increased thirst and urination, a general investigation is initially required, including medical history and clinical examination. The veterinarian often takes blood and urine samples.
When Should a Veterinarian Be Consulted?
It can be difficult to measure how much a cat drinks or how often it urinates, but if the pet owner perceives that the cat has increased thirst or urination, it may be enough to need an examination.