• Polyuria (PU) and polydipsia (PD) refer to excessive urination and excessive drinking, respectively.
  • Polyuria and polydipsia can be associated with a variety of medical conditions.
  • Polyuria and polydipsia are signs of illness, so the treatment depends on the underlying cause. Fortunately, most conditions that cause polyuria and polydipsia are manageable or curable.

What Are Polyuria and Polydipsia?

Polyuria (PU) and polydipsia (PD) are the medical terms used to describe excessive urination and excessive drinking, respectively. Because these two abnormalities tend to occur together, the abbreviation PU/PD is commonly used.

What Causes Polyuria and Polydipsia?

With rare exceptions, any time an animal drinks increased amounts of water, urination increases. This is part of the body’s natural way of maintaining fluid balance. Similarly, if the body is unable to retain appropriate amounts of water for some reason, the pet receives signals from his or her body to drink more water to combat dehydration.

The processes that control fluid regulation are complex and involve the kidneys, brain, and other organs, as well as hormones and other chemicals in the body. Polyuria and polydipsia can be associated with a variety of medical conditions that may involve alterations in any of these regulatory processes. Conditions associated with PU/PD include the following:

  • Diabetes
  • Kidney disease
  • Thyroid disease (in cats)
  • Adrenal gland disease
  • Pyometra (uterine infection)

Certain medications, such as steroids, can also cause increased drinking and urination as a side effect.

What Are the Clinical Signs of Polyuria and Polydipsia?

Polyuria and polydipsia are not always easy to detect, particularly if there are multiple pets in the home. PU/PD can also be mistaken for other medical issues, like urinary incontinence or a bladder infection. If your pet seems to be spending more time at the water bowl, or asking to go outside more often than usual, PU/PD may be occurring. Other signs of a problem may include the following:

  • Urinary accidents in the house
  • Urinating outside the litterbox (cats)
  • Drinking from toilets, sinks, or other water sources besides the water bowl

Additional clinical signs may result from the underlying condition that is causing the PU/PD. For example, pets with kidney disease may vomit, lose weight, or stop eating in addition to exhibiting PU/PD. Unless directed by your veterinarian, you should never limit your pet’s access to water.

How Are Polyuria and Polydipsia Diagnosed?

A medical history and physical examination findings can provide valuable information for your veterinarian. The medical history may include trying to determine how long the problem has been going on and whether any other signs of illness have been observed. Physical examination findings may reveal evidence of underlying illness. For example, a female dog with a uterine infection may have a vaginal discharge, and a cat with thyroid disease may have an increased heart rate and weight loss.

Your veterinarian may recommend a urinalysis, serum chemistry profile, complete blood count, or other initial diagnostic tests to begin looking into the cause of your pet’s PU/PD. Additional testing for specific diseases, such as adrenal gland disease, may be recommended based on the results of preliminary tests.

How Are Polyuria and Polydipsia Treated?

Polyuria and polydipsia are not diseases—they are signs of illness. Therefore, the treatment for PU/PD depends on the underlying cause. Fortunately, most conditions that cause PU/PD are manageable or curable. If you suspect your pet may be drinking or urinating excessively, schedule an appointment with your veterinarian so that diagnostic testing can begin.