A cat that’s suddenly peeing more than usual is almost always signaling a medical problem. Healthy cats produce about 10 to 20 mL of urine per kilogram of body weight per day, so a 10-pound (4.5 kg) cat typically produces roughly 45 to 90 mL daily. If you’re noticing larger clumps in the litter box, more frequent trips, or wet spots outside the box, something has changed inside your cat’s body, and the most common causes are treatable when caught early.
Large Volumes vs. Frequent Small Amounts
Before anything else, it helps to figure out what “peeing so much” actually looks like for your cat, because the two patterns point to very different problems. A cat producing large volumes of urine each time, with noticeably bigger litter clumps, has polyuria. This typically means something is wrong with how the kidneys filter and concentrate urine, or how the body manages blood sugar or hormones. You’ll usually also notice your cat drinking a lot more water than usual.
A cat making frequent trips to the litter box but only passing small amounts, sometimes straining or crying, has a lower urinary tract issue like inflammation, infection, or crystals in the bladder. This pattern is called pollakiuria, and it signals irritation rather than overproduction. Cats with lower urinary tract problems often lick their genital area excessively and may urinate just outside the litter box, as if they couldn’t quite make it in time.
The distinction matters because the causes, urgency, and treatments are completely different.
Kidney Disease
Chronic kidney disease is one of the most common reasons older cats start peeing more. Kidneys normally concentrate urine by pulling water back into the body, but as kidney tissue deteriorates, that ability fades. The result is dilute, watery urine in large volumes. By the time you notice increased urination, roughly two-thirds of your cat’s functional kidney tissue has already been lost.
Cats with kidney disease often lose weight gradually, eat less, and may vomit occasionally. Because they’re losing so much water through urine, they’re at constant risk of dehydration, even if they seem to be drinking nonstop. The disease can’t be reversed, but early detection lets you slow progression significantly with diet changes and fluid support.
Diabetes
Diabetes in cats works similarly to type 2 diabetes in humans. When blood sugar stays elevated, the excess glucose spills into the urine and pulls water along with it, creating large volumes of sweet-smelling urine. The hallmark signs are a cat that eats ravenously, drinks constantly, pees excessively, and still loses weight.
Cats with diabetes often develop a distinctive flat-footed walk, placing their whole hind foot on the ground instead of walking on their toes. This happens because prolonged high blood sugar damages the nerves in the back legs. The good news is that some cats achieve remission with early, aggressive treatment, meaning their blood sugar normalizes and they no longer need ongoing intervention.
Overactive Thyroid
Hyperthyroidism is extremely common in cats over 10 years old. The thyroid gland produces too much hormone, which ramps up the entire metabolism. Heart rate, appetite, and energy all increase, and so does kidney blood flow. The excess thyroid hormone changes how blood moves through the kidneys and disrupts the normal process of concentrating urine, leading to increased output.
Cats with hyperthyroidism often seem unusually active or restless for their age, lose weight despite eating well, and may have a greasy or unkempt coat. Vomiting and diarrhea are also common. A simple blood test measuring thyroid hormone levels confirms the diagnosis, and several effective treatment options exist.
Urinary Tract Infections and Inflammation
Bladder infections and a condition called feline idiopathic cystitis (inflammation with no identifiable infection) cause frequent, urgent urination in small amounts rather than large volumes. Your cat may cry in the litter box, produce urine that smells unusually strong, or leave small puddles near the box or by doors. You might see pink-tinged urine if there’s bleeding in the bladder.
Stress is a major trigger for bladder inflammation in cats. Moving to a new home, a new pet in the household, or changes in routine can all set it off. Younger cats are more prone to inflammation without infection, while older cats are more likely to have a true bacterial infection.
When It’s Actually Spraying
Sometimes what looks like excessive peeing is actually territorial marking. Spraying cats stand upright, back up to a vertical surface, and release small amounts of urine with a quivering tail. The urine typically hits walls, furniture legs, or doorframes at about nose height. This is a behavioral issue, not a volume problem. Your cat is still urinating normally in the litter box in addition to spraying. Intact males spray the most, but neutered males and females can spray too, especially when stressed or when outdoor cats are visible through windows.
A Dangerous Exception: Urinary Blockage
If your cat (especially a male) is straining in the litter box and producing no urine or only a few drops, this is a life-threatening emergency, not just excessive urination. A complete urinary blockage can cause kidney failure, dangerous heart rhythm changes, and death within 24 to 48 hours. Blocked cats often cry out in pain, become lethargic, vomit, or hide. If you’re not sure whether your cat is actually producing urine, treat it as an emergency and get to a vet immediately.
How the Cause Gets Diagnosed
Your vet will typically start with a physical exam, a complete blood panel, a urinalysis, and a urine culture. The urinalysis is especially important because it measures urine concentration, called specific gravity. Healthy kidneys produce concentrated urine. If the urine is consistently dilute, that narrows the possible causes quickly.
Blood work checks kidney values, blood sugar, liver function, and electrolytes, including calcium levels (elevated calcium is an underrecognized cause of excessive urination in cats). For cats over about eight years old, a thyroid hormone level is part of the standard workup. If these initial tests don’t provide an answer, your vet may recommend ultrasound or X-rays to look for structural problems like tumors or kidney abnormalities.
Tracking Changes at Home
If you use clumping litter, you already have a rough monitoring tool. Research has shown that clump weight reliably tracks urine volume, so paying attention to clump size over a few days gives you useful data. A 10-pound cat normally produces clumps totaling roughly a fist-sized amount per day. If you’re scooping noticeably more than that, or if the clumps are consistently larger than what you’re used to, that’s a real change worth investigating.
Keeping track of water intake helps too. Measure how much water you put in the bowl each morning and check how much is left at night. Cats on dry food typically drink more than cats on wet food, but a sudden increase in drinking for any cat is significant. For reference, anything above 100 mL per kilogram of body weight per day (roughly half a cup daily for a 10-pound cat) is considered excessive.
Write down what you observe for a few days before your vet visit: how many times your cat visits the litter box, whether the clumps are large or small, any straining or vocalizing, and how much water disappears from the bowl. These details help your vet zero in on a diagnosis faster.