Section: Overview
The term polydipsia refers to excessive thirst manifested by excessive water intake, which in turn usually leads to polyuria, which is the formation and excretion of a large volume of urine. Polydipsia and polyuria are early signs of several diseases, including:
Kidney failure
Diabetes mellitus
Hyperactivity of the thyroid gland
Uterine infection (called pyometra)
Liver disease
High blood calcium
Uncommon abnormalities of the pituitary gland
Inability of the tubules of the kidney to reabsorb water properly (i.e. "nephrogenic" diabetes insipidus
Cats normally take in about 20 to 40 milliliters per pound of body weight per day, or about 2 ½ cups per day for a 10 pound cat. This includes any water that is taken in when eating canned food. Anything more than that, under normal environmental conditions, is considered polydipsia.
You should watch your cat for increased thirst and urinations. You may observe an increase in the amount of wet litter in a cat's litter box. Some cats may begin drinking from a dripping faucet in the sink or from an open toilet bowl. However, if you want to determine how much your cat is drinking, allow him only one source of water and subtract the amount left in the bowl after 24 hours from the amount you put in originally. If you determine that your pet is drinking excessively, make an appointment with your veterinarian.
Diagnosis
One of the first steps in the evaluation of a cat with polyuria and polydipsia is to determine the urine concentration by a test called "urine specific gravity." The specific gravity of pure water is 1.000. Polyuria is suspected if the urine specific gravity is less than 1.035. This can be verified by measuring daily urine output. Polyuria is present if the cat's daily urine output is greater than 20 milliliters per pound of body weight per day.
Several diagnostic tests may be needed to determine the cause of polyuria and polydipsia because many different diseases may cause these symptoms. Tests may include:
Complete medical history and physical examination including palpating the abdomen to check kidney and liver size, checking for vaginal discharge in females and palpating the thyroid gland.
The history that includes the determination of drug administration (e.g. diuretics, anticonvulsants, cortisone-type drugs, salt; or recent fluid therapy); reproductive status (i.e. sexually intact or spayed) in females; occurrence of urinary accidents in the house; abnormal odor or appearance of the urine; and the presence of weight loss, appetite change, or any other abnormalities.
Treatment
There are several potential causes of polyuria and polydipsia, and the underlying cause of these symptoms must be determined before appropriate treatment can be initiated.
The occurrence of polyuria and polydipsia usually does not constitute an emergency, but several potentially serious diseases (such as diabetes mellitus, kidney failure, liver failure or high blood calcium caused by a malignancy) may be the underlying cause of the symptoms. Hypercalcemia can be a medical emergency and if identified should be treated appropriately with intravenous saline solution and diuretics.
Home Care
You should also monitor your cat for any clinical abnormalities and discuss them with your veterinarian. Monitor the amount of water consumed by your cat and try to identify any changes in urinary behavior and urine output. Also monitor your cat's appetite and activity level. Discuss any changes you observe or concerns you may have with your veterinarian.
Polyuria and polydipsia cannot be prevented, and successful treatment depends on identification of the underlying disease causing these symptoms.
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