A cat that isn’t peeing may have a urinary blockage, which is one of the most dangerous emergencies in feline medicine. When urine flow stops completely, toxins build up in the bloodstream and can kill a cat within 48 hours. If your cat has been straining in the litter box without producing urine, especially if it’s a male cat, this warrants an immediate trip to the vet.
Not every case is a full blockage. Some cats produce less urine due to painful inflammation or partial obstructions. But distinguishing between “painful but still peeing” and “completely blocked” at home is difficult, and the stakes are too high to guess wrong.
Why Blockages Are So Dangerous
When a cat can’t urinate at all, the kidneys keep filtering blood but have nowhere to send the waste. Potassium, a mineral normally excreted in urine, accumulates in the bloodstream. Rising potassium levels disrupt the electrical signals that keep the heart beating in rhythm, causing the heart rate to slow dangerously and eventually triggering fatal cardiac arrest. Cats that have been blocked for more than 24 hours often start vomiting, become extremely weak, and may collapse. Death typically follows within 48 hours of a complete obstruction.
Male Cats Are at Much Higher Risk
Male cats are far more likely to develop a complete urinary blockage than females, and the reason is anatomy. A male cat’s urethra (the tube that carries urine out of the body) is long and narrow, measuring roughly 8.5 to 10.5 centimeters. At its narrowest point, the internal diameter drops to less than 1 millimeter. That’s thin enough for a small mineral crystal, a clump of mucus, or a tiny stone to completely seal it shut. Female cats have a shorter, wider urethra, so while they can develop urinary problems, total blockages are rare.
The Most Common Causes
Several conditions fall under the umbrella of feline lower urinary tract disease, and any of them can reduce or stop urine output.
Feline Idiopathic Cystitis
The single most common cause of urinary symptoms in cats is feline idiopathic cystitis (FIC), a painful inflammation of the bladder with no identifiable underlying cause. Cats with FIC make frequent trips to the litter box, strain while trying to urinate, and often have blood in their urine. In many cases they still pass small amounts of urine, but the inflammation can trigger swelling or spasms that contribute to a full blockage, particularly in male cats. Stress is considered a major trigger.
Urinary Stones
Mineral crystals in the urine can clump together into solid stones called uroliths. The two most common types in cats are struvite stones (made of magnesium, phosphorus, and ammonia) and calcium oxalate stones. These stones irritate the bladder lining and, if small enough to travel into the urethra, can lodge there and block urine flow entirely.
Urethral Plugs
Urethral plugs are soft, paste-like masses made of minerals, cells, and a mucus-like protein. They form in the urethra itself and are one of the most frequent causes of complete blockage in male cats. Unlike hard stones, plugs are compressible, but they’re just as effective at sealing off that narrow tube.
How to Tell If Your Cat Is Blocked
The tricky part is that a blocked cat and a cat with a painful bladder infection look similar in the early stages. Both will visit the litter box frequently, crouch and strain, vocalize, and lick their genital area. Here’s what separates the two:
- Partial or nonobstructive problems: The cat still produces some urine, even if it’s just drops. The bladder feels small when you gently press the lower belly. You may see blood-tinged urine in the litter box.
- Complete blockage: No urine comes out despite repeated straining. The bladder becomes visibly distended and feels like a hard, tennis-ball-sized lump in the lower abdomen. The cat may cry out in pain when you touch it. As hours pass, the cat becomes lethargic, stops eating, and may vomit.
If you scoop your cat’s litter box regularly, you’ll notice the absence of urine clumps quickly. This is one of the reasons vets recommend daily scooping: it’s your earliest warning system.
What Happens at the Vet
A vet can confirm a blockage within minutes by feeling the bladder. A blocked cat’s bladder is large, firm, and painful, and it won’t release urine when gentle pressure is applied. Blood tests check potassium levels and kidney function, and an ECG may be run if the heart rhythm is abnormal.
The immediate treatment is to pass a thin catheter through the urethra to drain the bladder. This is done under sedation or anesthesia. Most cats stay in the hospital for one to three days afterward with the catheter in place, receiving IV fluids to flush toxins out of the bloodstream and restore normal electrolyte balance. Once the catheter is removed, the vet monitors whether the cat can urinate on its own before sending it home.
For cats that block repeatedly, a surgery called perineal urethrostomy may be recommended. This procedure creates a wider opening for urine to pass through, bypassing the narrowest part of the urethra. It’s effective at preventing re-obstruction, but it does carry risks including urinary tract infections (the wider opening makes it easier for bacteria to enter), scarring that narrows the new opening, and, in rare cases, incontinence.
Preventing Future Episodes
Once a cat has had one urinary episode, the chance of recurrence is significant. Prevention focuses on two things: diet and water intake.
Therapeutic urinary diets work by controlling the mineral content of the food, which changes the chemistry of the urine to make crystal formation less likely. These diets keep the urine’s mineral concentration below the threshold where struvite or calcium oxalate crystals start to form. Your vet will recommend a specific formula based on the type of crystals or stones your cat has produced.
Water intake matters enormously. Dilute urine is less likely to form crystals than concentrated urine. Switching from dry food to wet food is one of the most effective changes you can make, since canned food is roughly 75% water. Many cats also drink more from a running water fountain than from a still bowl. Placing multiple water sources around the house helps, too.
Because stress plays a role in feline idiopathic cystitis, environmental enrichment matters. Cats do better with predictable routines, enough litter boxes (one per cat plus one extra), vertical spaces to climb, and quiet retreats away from other pets or household chaos. In multi-cat households, competition for resources is a common and underappreciated stressor.
Less Urgent Reasons for Reduced Urination
Not every case of reduced urination is an emergency. Cats that are dehydrated from illness, heat, or simply not drinking enough will produce less urine. Kidney disease, which is common in older cats, can change urination patterns in both directions: early kidney disease often causes increased urination, while advanced disease may reduce output. A recent change in diet, especially switching to dry food, can also lower urine volume without indicating a blockage.
The key distinction is whether your cat is producing some urine versus none at all. A cat that’s peeing less than usual deserves a vet visit soon. A cat that’s producing no urine and straining repeatedly needs to be seen within hours.