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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 and 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 and sometimes none at all.
There are many causes of polyuria/polydipsia, some of which include;
- Diabetes mellitus - Either caused by insufficient insulin secretion or an insulin resistance.
- Chronic renal failure
- Hyperthyroidism - Benign tumour of the thyroid gland which leads to the excess secretion of thyroid hormones.
- Pyometra - Infection of the uterus.
- Liver disease
- Cushings disease (hyperadrenocorticism)
- 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 - Compulsive water drinking.
- 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 and veterinary attention must be sought immediately.
Your veterinarian will perform a physical examination of your cat and 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 and liver, check for vaginal discharge and 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) and urinalysis to evaluate for diabetes mellitus acromegaly and hyperadrenocorticism, hyperglycemia, ketones, glucose, low urine specific gravity, liver disease, hyperbilirubinemia, decreased BUN, increased ALT, ALP, GGT, bilirubinuria, renal disease (elevated BUN and creatinine with a decreased urine specific gravity, hyperphosphatemia), hyperthyroidism (increased ALT and or ALP, mild increase in PCV, low urine specific gravity) and hypokalemia.
- Total T4 to evaluate for hyperthyroidism.
- Abdominal x-ray or ultrasound may help identify pyometra, renal disease, and liver disease.
- Water deprivation 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 and psychogenic polydipsia. It should not be performed on cats with renal insufficiency.
Treatment depends on the underlying cause.
- Diabetes mellitus - Dietary changes (low protein diet) and insulin (if required).
- Chronic renal failure - Dietary changes (low protein and phosphorous diet), phosphorous binders to manage elevated phosphorous levels in the blood, fluids (if dehydrated), anti-nausea medications and careful monitoring.
- Hyperthyroidism - Radioactive iodine is the most common treatment if this is not medically indicated, surgical removal of the tumour.
- Pyometra - Antibiotics to treat the infection and removal of the uterus.
- Liver disease - Nutritional support, an anti-nausea medication. If the cause of liver failure is a portosystemic shunt, surgery.
- Cushing's syndrome (hyperadrenocorticism) - Surgical removal of the affected adrenal gland (if an adrenal tumour is the cause), surgical removal of both adrenal glands (if a pituitary tumour is involved), gradual withdrawal of steroids if the cause is veterinary induced.
- Hypercalcemia (high blood calcium concentration) - Fluid therapy, loop diuretics increase calcium extraction from kidneys, steroids to decrease bone resorption, surgery to remove abnormal parathyroid gland (in primary hyperparathyroidism).
- Acromegaly - There is no cure for this disease, treatment is aimed at management.
- Hypokalemia - Treating the underlying cause, oral or intravenous potassium.
- Urinary tract infection - Antibiotics to treat the infection.
Supportive care such as fluid therapy may be necessary for cats who are dehydrated.
Some drugs can cause polyuria/polydipsia - Withdrawal or replacement of medications if possible.
For further info on some of the terms used in this article, please read our glossary page.