Overview:

Frequent urination (polyuria) goes hand in hand with frequent drinking (polydipsia). It isn't a disease but a symptom of a medical problem. It is defined as the excessive production & elimination of urine. There are many causes of frequent urination in cats which we will look at in this article. Frequent urination differs from urgent urination in that the cat produces excessive amounts of urine whereas in urgent urination, the cat may visit the litter tray frequently but only pass small amounts of urine & sometimes none at all.

What are the causes of polyuria/polydipsia in cats?

There are many causes of polyuria/polydipsia, some of which include;

• Diabetes mellitus
• Chronic renal failure
• Hyperthyroidism
• Pyometra
• Liver disease
  
• Cushings disease (hyperadrenocorticism)
  
• Diabetes insipidus
• Hypercalcemia (high blood calcium concentration)
• Acromegaly (excess of growth hormone in an adult cat, most often caused by a growth hormone secreting pituitary tumour)
• Hypokalemia (abnormally low potassium concentration in the blood)
• Psychogenic polydipsia
• Some drugs can cause polyuria/polydipsia

Frequent urination without passing much liquid may be a cause of a UTI (urinary tract infection).

Frequent passing of small amounts of urine either with or without straining may be caused by FLUTD. This is a medical emergency & veterinary attention must be sought immediately.

Diagnosis of polyuria/polydipsia:

Your veterinarian will perform a physical examination of your cat & obtain a medical history including any medications your cat is on which could have resulted in this. He will palpitate the abdomen to feel the size of the kidneys & liver, check for vaginal discharge & palpitate the thyroid gland.

He will want to perform some tests to determine the cause of the frequent urination. These tests may include;

• Complete blood count, Chemistry profile (biochemistry profile), Urinalysis to evaluate for diabetes mellitus acromegaly & hyperadrenocorticism (hyperglycemia, ketones, glucose, low urine specific gravity) , liver disease (hyperbilirubinemia; decreased BUN; increased ALT, ALP, GGT, bilirubinuria), renal disease (elevated BUN & creatinine with a decreased urine specific gravity, hyperphosphatemia), hyperthyroisism (increased ALT and or ALP, mild increase in PCV, low urine specific gravity) & hypokalemia.
• Total T4 to evaluate for hyperthyroidism.
• Abdominal x-ray or ultrasound may help identify pyometra, renal disease & liver disease.
• Water depravation test to see if the volume of urine decreases. This is typically performed after common causes of polyuria have been excluded to evaluate for diabetes insipidus & psychogenic polydipsia. It should not be performed on cats with renal insufficiency.

How is polyuria/polydipsia treated?

Treatment depends on the underlying cause.

Fluid therapy may be necessary in cats which are dehydrated.

References:

For further info on some of the terms used in this article, please read our glossary page.