Polydipsia and Polyuria (excessive drinking and urinating) in Cats

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Overview of Excessive Drinking and Urinating in Cats

The term polydipsia refers to a cat’s 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 is commonly abbreviated and discussed using the letters “PU/PD”. 

Below is an overview of causes, diagnosis and treatment of excessive drinking and urinating in cats followed by detailed information about this condition. 

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 of Polydipsia and Polyuria (PU/PD) in Cats

    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 of Polydipsia and Polyuria (PU/PD) in Cats

    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.

    In-depth Information on Feline Polydipsia and Polyuria

    Polyuria and polydipsia are not specific for any one disease but can be caused by several disorders in cats including:

  • Endocrine (hormonal) disorders
  • Hyperadrenocorticism (overactivity of the adrenal glands)
  • Hyperthyroidism (overactivity of the thyroid glands)
  • Diabetes mellitus
  • Kidney disorders
  • Renal glucosuria (a defect of the kidney tubules leading to spillage of glucose in the urine)
  • Kidney failure (more commonly acute but sometimes chronic)
  • Pyelonephritis (infection of the kidneys)
  • Increased production of urine after relief of urinary tract obstruction (so-called “post-obstructive diuresis”)
  • Loss of normal salts and chemicals (i.e. urea) in the kidney that facilitate water reabsorption (so-called “renal medullary washout”)
  • Impaired response of the kidney tubules to anti-diuretic hormone that normally promotes water reabsorption (so-called “nephrogenic” diabetes insipidus)
  • Electrolyte abnormalities
  • High blood calcium concentration (hypercalcemia)
  • Low blood potassium concentration (hypokalemia)
  • Abnormally high red blood cell numbers leading to thickened blood called “polycythemia”)
  • Infection of the uterus (called “pyometra”)
  • Liver disease
  • Defective release of anti-diuretic hormone from the pituitary gland (called “central” or “pituitary” diabetes inspidus)
  • Psychogenic polydipsia (a behavioral problem that leads to compulsive water drinking)
  • Administration of fluids, salt, diuretics or cortisone-like drugs
  • The most common causes of polyuria and polydipsia in cats are chronic kidney failure, hyperthyroidism and diabetes mellitus.
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