Polydipsia and Polyuria (excessive drinking and urinating) in Dogs

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, 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)

Dogs normally take in about 20 to 40 milliliters per pound of body weight per day, or about 3 to 4 cups of water per day for a 20 pound dog. Anything more than that, under normal environmental conditions, is considered polydipsia.

You should watch your dog for increased thirst and urinations. Some dogs 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 dog 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 dog 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 dog'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