If you feel like you’re refilling your pet’s water dish more often than usual, you may want to pay close attention. Excessive thirst, or polydipsia, is usually coupled with excessive urination, or polyuria. Because the two tend to occur at the same time, veterinarians shorten the general condition to “PU/PD” (polyuric/polydipsic).
Excessive thirst is driven by your pet’s body’s need to compensate for excessive urination. But how can you tell how much is too much? Polydipsia is defined as drinking more than 100 ml of water per kilogram (or about 1.5 ounces per pound) per day. This means that a 30-lb. dog can drink about five and a half cups of water a day without it being considered excessive.
External causes may be to blame for excessive thirst. It could be a side effect of some medications, including diuretics and steroids. Overly salty diets, hot weather and increased exercise will also drive your pet to the water bowl. If you’ve ruled out those causes, a trip to the vet should be your next step.
In puppies and kittens, polydipsia may indicate a congenital problem such as kidney malformation, diabetes insipidus or a liver shunt. In adult pets, excessive thirst may be a symptom of any number of causes, including diabetes, hyperthyroidism, kidney disease or hypercalcemia of malignancy.
Many of these conditions are treatable. To find out what is ultimately driving your pet to drink like a fish, it’s likely that your vet will want to perform a urinalysis and blood work.