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Ask a Vet: Why Can’t My Cat Urinate?

Urinary obstruction happens almost exclusively in male cats, and they generally die within 24 hours if they do not receive treatment.

Dr. Eric Barchas  |  Sep 1st 2015


Urinary obstruction is one of the worst things that can happen to a cat. In addition to being miserably painful, it is urgently life-threatening. Anyone who owns a male cat needs to be aware of the syndrome, and any time a male cat exhibits any unusual behavior in the litter box the matter should be treated as an emergency. If you want to test a veterinary office, call them and say that your male cat is having litter box problems. If they say anything other than “come in immediately,” then you may want to find another vet.

I find it amazing that I grew up with cats and never heard about urinary obstruction until I was in vet school. It is a very common problem (at any point in time, there usually is at least one cat — and often there are several — under treatment for it in the hospital where I work).

So, what is urinary obstruction? What causes it? What is the best way to treat it? How can it be prevented? Of these questions, only the first is not a source of controversy in veterinary medicine.

Let’s answer that first question. Urinary obstruction is a syndrome in which cats can’t urinate. It happens almost exclusively in male cats, who are naturally endowed (or rather, poorly endowed) with a small urethra. If the urethra spasms or if a plug of mucus or crystalline debris blocks the urethra, the cat suffers from an inability to urinate.

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Photo of Dr. Eric Barchas by Liz Acosta

That sounds painful, and affected cats certainly behave as if it is (we can’t ask them whether it hurts, but I’m 100 percent confident that it does). When a cat can’t urinate, the bladder fills until it reaches maximum capacity. I can’t imagine the agony that this causes.

Unfortunately, pain is only part of the problem. After the bladder has filled to its maximum capacity, there is nowhere for urine to go. The kidneys, which produce urine, therefore shut down. Cats with urinary obstruction thus go into kidney failure. They also suffer from acute electrolyte imbalances. In particular, blood potassium levels increase precipitately. High potassium levels lead to cardiac arrest. Cats with urinary obstruction generally die within 24 hours if they do not receive treatment.

The good news is that, with treatment, survival rates range from 90 percent to 95 percent and the kidney failure usually is completely and permanently reversible. However, there is more bad news: 15 percent to 40 percent of cats who suffer from an episode of urinary obstruction later will suffer another episode.

What causes urinary obstruction? What is the best way to treat it? How can it be prevented? At the start of this year I received my bimonthly Journal of Veterinary Emergency and Critical Care. I was extremely interested to read a paper titled “Controversies in the management of feline urethral obstruction,” from which I learned that everything about the treatment of urinary obstruction is controversial.

Vet gives cat a checkup by Shutterstock

Vet gives cat a checkup by Shutterstock

So please know this: Experts are not in complete agreement about anything that follows. And, I am about to commit the crime of offering information that is not evidence-based (which means that what follows is based upon my personal experience rather than controlled scientific studies). However, as I mentioned, urinary obstruction is very common. I have a lot of experience with it, so I feel that I have a reasonable handle on what works and what doesn’t.

The cause of urinary obstruction is controversial, but in my experience most cases are linked to a condition called FIC, which is short for feline idiopathic cystitis. The syndrome also has been known as FLUTD (feline lower urinary tract disease), FUS (feline urological syndrome), and Pandora syndrome. I like FIC, because it describes the syndrome and its confusing nature best. Everyone knows what feline means. Idiopathic means cause unknown to medical science. Cystitis means inflammation of the bladder.

FIC causes cyclical irritation of the bladder and urethra. Symptoms in females are identical to bladder infections — they may suffer from pain, house soiling, frequent attempts to urinate, and bloody urine. Males suffer from all of these symptoms as well, but because of their small urethras they also are prone to urinary obstruction.

The cause of FIC is, as its name implies, unknown. Stress plays a role. Obesity may play a role. Strong, concentrated urine appears to play a role. And, in my experience, urine chemistry plays a role. Urine chemistry is linked to diet, so I’m going to go ahead and say something controversial: I think (but cannot prove) there is something wrong with commercial cat foods that is increasing the prevalence of the syndrome.

I have successfully treated many hundreds, or perhaps thousands, of cats for urinary obstruction. In my experience the best outcomes occur when cats are hospitalized for several days with a urinary catheter in place. Intravenous fluids are administered to help dilute the urine. Pain killers and antispasmodic medications appear to be beneficial. Antibiotics usually are not indicated, at least until the urinary catheter is removed.

Cat in litter.

Red-haired cat in a litter box Shutterstock.

After several days, the urinary catheter is removed and then I hold my breath and wait for the cat to urinate. Most of the time he can; however, around 10 percent of cats require an immediate second round of catheterization. (As a side note, if anyone had told me 20 years ago how much time I’d spend waiting for cats to urinate, and how happy I would be when they did, I would have thought they were crazy.)

After the crisis is over, I recommend temporary use of antispasmodic medications and a permanent diet change to a wet formula that is specifically formulated to prevent urinary problems. I do not for the life of me understand why all cat foods are not formulated to prevent urinary problems, but they aren’t.

In my experience most cats who undergo a diet change do not suffer from repeated urinary obstructions. Some unfortunate individuals, however, do. For some cats the condition is so intractable that they must undergo a surgery, called perineal urethrostomy, in which the penis is removed and a new urinary orifice is created. For obvious reasons perineal urethrostomy is not my first choice treatment.

The take-home message is that owners of male cats must be forever vigilant. If your boy is having any troubles in the litter box, don’t assume it’s not a serious problem. It could be the first sign of a life-threatening urinary obstruction.

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