Why Is My Cat Peeing a Lot？3 Serious Causes & Signs

When a cat is peeing a lot, it’s a significant health signal that should never be ignored. It’s important to make a distinction:

• Polyuria: This is the medical term for urinating a large volume. The clumps are bigger, and your cat is likely drinking a lot more water to compensate (this is called polydipsia). This article focuses on this symptom.
• Pollakiuria: This is urinating frequently, but in small, often strained amounts. This typically signals a urinary tract infection (UTI), bladder stones, or inflammation.

A cat producing large volumes of urine is almost always a sign of a serious underlying medical condition, most commonly kidney disease, diabetes, or hyperthyroidism. Here’s what you need to know.

• It’s a Major Medical Sign: A cat suddenly peeing large volumes of urine (known as polyuria) is a significant warning sign. It is almost always linked to a serious underlying medical condition, not a behavioral issue.
• The “Big Three” Causes: The most common causes for a cat peeing a lot are Chronic Kidney Disease (CKD), Diabetes Mellitus, and Hyperthyroidism. All are serious but manageable if caught early.
• Don’t Be Fooled by “Acting Normal”: A cat peeing a lot but otherwise acting fine is a common scenario. Cats hide illness well. The increased urination is the early warning sign; do not wait for your cat to become lethargic or stop eating.
• Emergency Red Flags: If your cat is peeing a lot and stops eating, becomes lethargic, or is vomiting, it is a medical emergency. This combination suggests the underlying disease has progressed to a critical stage.
• Vet Diagnosis is Non-Negotiable: You cannot solve this problem at home. A veterinarian must run blood tests and a urinalysis to get a precise diagnosis and create a treatment plan, which could include medication, insulin, or a prescription diet.

Here are the most common physiological reasons:

• Chronic Kidney Disease (CKD): This is a very common cause, especially in older cats. Healthy kidneys concentrate urine, reabsorbing water back into the body. Diseased kidneys lose this ability. They can’t stop water from being flushed out, so the cat produces huge volumes of dilute, pale urine. They drink more and more to fight off the resulting dehydration.
• Diabetes Mellitus: In diabetic cats, there is too much glucose (sugar) in the blood. The kidneys try to filter this sugar out, and water follows the glucose into the urine, leading to a high volume of pee. You may also notice your cat has a ravenous appetite but is losing weight.
• Hyperthyroidism: An overactive thyroid gland (common in senior cats) speeds up the entire body, including the metabolism and blood flow to the kidneys. This increases urine production and also makes the cat intensely thirsty. Other signs include weight loss, hyperactivity, and a rough-looking coat.
• Urinary Tract Infection (UTI) / Bladder Crystals: While often causing frequent, small urinations, a severe infection or irritation can sometimes lead to a general loss of bladder control or increased urgency, which may be perceived as “peeing a lot.”
• Liver Issues: Liver disease can interfere with the body’s water regulation, leading to increased thirst and urination.
• Medication-Related Causes: Drugs like corticosteroids (steroids) or diuretics (often for heart conditions) are designed to increase urination.

• Frequency: A healthy adult cat typically urinates 1 to 3 times per day.
• Volume: This is harder to measure, but you should have a general idea of your cat’s normal “clump size” in the litter box. “Peeing a lot” means these clumps are suddenly and consistently much larger—sometimes double or triple the normal size.
• Diet: A cat on an all-wet-food diet will naturally pee more (and have more dilute, healthier urine) than a cat on an all-dry-food diet, as they are getting significantly more moisture.

You are looking for a change from the norm. A sudden increase in either frequency or clump size that lasts for more than a day is a clear sign to call your vet.

This is a dangerous assumption. Cats are masters at hiding illness.

• Early-Stage Disease: In the early stages of chronic kidney disease and diabetes, increased thirst and urination are often the only symptoms. The cat doesn’t feel “sick” yet.
• Hyperthyroidism: This disease can actually cause a surge in energy, making a cat seem more “normal” or even hyperactive.

The Symptom IS the Warning: The increased urination is the warning sign. By the time a cat with CKD or diabetes starts “acting sick” (like not eating or being lethargic), the disease is much more advanced and harder to manage. Do not wait for other symptoms to appear.

• Advanced Kidney Disease: When the kidneys fail, toxins (like urea) build up in the bloodstream. This condition, called uremia, causes severe nausea, vomiting, and a complete loss of appetite.
• Severe Diabetes (DKA): Unmanaged diabetes can lead to Diabetic Ketoacidosis (DKA), a life-threatening complication where the body, starved for energy, starts burning fat and produces toxic byproducts called ketones. This causes vomiting, lethargy, and a loss of appetite.
• Urinary Infection: A severe kidney or bladder infection can cause fever, pain, and nausea, making the cat refuse food.

If your cat is showing both of these symptoms, they need to see a veterinarian immediately.

There are two main explanations:

• They ARE Drinking—From Food: This is the most common and benign reason. If you recently switched your cat to a wet-food diet, they are getting the vast majority of their hydration from their meals. They may rarely, if ever, visit the water bowl. Their increased urine output is healthy and normal in this context.
• They Are Medically Unable: This is the serious scenario. The cat’s kidneys have completely lost the ability to concentrate urine and are just passively flushing water out. The cat should be desperately thirsty but may be too sick, nauseous, or lethargic (from kidney failure or another disease) to get up and drink. This is an advanced, critical stage of illness.

Observe your cat’s total moisture intake. If they are on dry food and truly not drinking but still peeing a lot, it is an emergency.

• Chronic Kidney Disease (CKD)
• Diabetes Mellitus (Sugar Diabetes)
• Hyperthyroidism (Overactive Thyroid)
• Urinary Tract Infection (UTI)
• Bladder/Urethra Inflammation (Cystitis)
• Medication Side Effects (especially steroids or diuretics)
• Liver Disease
• Diet-Related Causes (e.g., a switch to a high-moisture diet)

What to expect at the vet:

• Full Physical Exam: The vet will check your cat’s weight, feel their kidneys and bladder, and listen to their heart.
• Urinalysis: You will likely be asked to bring in a urine sample (or they will collect one). This test is crucial. It checks for:
  • Urine Specific Gravity (USG): Measures urine concentration. Very dilute urine points to kidney disease, hyperthyroidism, or diabetes.
  • Glucose: Sugar in the urine is a hallmark sign of diabetes.
  • Bacteria/Crystals: This identifies infection or bladder stones.
• Blood Tests: A blood panel is essential to get the final diagnosis.
• Chemistry Panel: Checks kidney values (BUN, creatinine), liver enzymes, and blood glucose.
• Thyroid Test (T4): A simple blood test checks for hyperthyroidism.

Common Treatment Examples:

• Diabetes: Treated with insulin injections and a special low-carbohydrate, high-protein diet.
• Kidney Disease: Cannot be cured, but can be managed for years with hydration support (like subcutaneous fluids), a prescription renal diet, and blood pressure medications.
• Hyperthyroidism: Managed with daily medication, a prescription diet, or radioiodine therapy (which can be curative).
• UTI: Treated with a course of antibiotics.

• Track Clump Size: Use a clumping litter. Don’t scoop for one 24-hour period (if you can) and take a photo. This gives the vet a clear visual of the volume.
• Measure Water Intake: Fill the water bowl to a specific line (or use a measuring cup) and note how much water is gone after 24 hours.
• Note Frequency: Simply keep a small notebook by the litter box and make a tally mark every time you see your cat use it.
• Collect a Sample: Your vet may give you a kit with non-absorbent litter beads to place in a clean, empty box. This allows you to collect a pure urine sample.
• Monitor Color: Is the urine pale and watery, or is it dark? Is it pink or reddish? (Red urine is an emergency).

• Can stress cause cats to pee more?
  Stress typically causes inappropriate urination (peeing outside the box) or frequent, strained urination (pollakiuria). It does not usually cause polyuria, or a large volume of urine.
• Is peeing more common in older cats?
  Yes. The “Big Three” causes—Chronic Kidney Disease, Diabetes, and Hyperthyroidism—are all diseases most commonly diagnosed in senior and geriatric cats (age 7+).
• Can diet alone increase urine output?
  Yes. A cat that switches from dry food to canned wet food will see a dramatic and healthy increase in their urine volume. This is good for their urinary tract health.
• When is increased urination a medical emergency?
  It is an emergency if it is paired with:
  • Not eating or vomiting
  • Extreme lethargy or collapse
  • Straining to pee with no urine coming out (this is a fatal blockage)
  • Pink, red, or brown urine
• Should I switch to wet food?
  In general, wet food is highly recommended by veterinarians for all cats. The high moisture content is excellent for kidney and bladder health and helps prevent dehydration.

Do not “wait and see.” Document the changes in water intake and urine output, and schedule an appointment with your veterinarian. Early diagnosis is the key to a long and healthy life for your companion.