Urethral Blockage in a Cat (Urolithiasis)

The urethra is a fine tube through which the cat urinates, and any blockage means the bladder can’t empty out — much like having a cork in a bottle.

Male cats are far more likely to experience urethral blockage than are females. By: jameswragg
Male cats are far more likely to experience urethral blockage than are females. By: jameswragg

Urethral blockage is a serious consequence of poor urinary health.

The urethra is the fine tube through which the cat urinates, and any blockage means the bladder cannot empty out — much like having a cork in a bottle. Not only is this excruciatingly uncomfortable, but it is also dangerous.

One of the consequences includes back pressure on the kidneys, which causes toxins to build up in the blood. There is also the risk of bladder rupture or even a heart attack (due to increased levels of blood potassium).

Urethral blockage is almost exclusively the preserve of the male cat (and dog — although this condition is less common in dogs). This is because of the S-shaped path that the male urethra traces. Debris, blood clots or stones can get stuck going around a corner.

If your cat shows signs of discomfort passing urine, always get him checked by your veterinarian. Early treatment can prevent a simple bladder infection from turning into something altogether more serious.

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In the early stages, the signs are those of discomfort when passing urine. This includes straining but only producing a few spots, constant attempts to urinate and bloody urine.

The cat may also start obsessively licking his rear end.

As the bladder fills and he becomes increasingly distressed, some cats stay in a semi-permanent squatting position, perhaps alternating with frantic bottom licking. Then, as levels of toxins build in his bloodstream, he becomes dull and lethargic, and eventually enters a stupor, falls into a coma and dies.

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Any small object — from a blood clot to a tiny bladder stone — can slip from the bladder into the urethra and cause a blockage.

Thus the causes of urethral obstruction are those associated with bladder problems (feline urinary tract disorders — FLUTD) such as infection, crystalluria (crystals in the urine), bladder calculi (bladder stones) or mineral sludge.

The latter is the result of urine being supersaturated with minerals and tends to occur in “couch potato” cats that don’t get up to drink and produce very strong urine. Other factors can trigger FLUTD, such as stress, which causes inflammation in the bladder lining, leading to blood clot formation.

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Consider switching to a wet food. By: Yusuke Chiba
Consider switching to a wet food. By: Yusuke Chiba


The symptoms of a cat repeatedly straining but not passing urine raise a strong suspicion of urethral blockage. This should be treated as an emergency, and the cat must be taken to the vet.

Diagnosis is made by feeling a large, hard bladder.

The deeper question is what caused the blockage in the first place. To investigate this, the veterinarian may scan the bladder for stones, analyze the urine and test for infection.


A cat with a urinary obstruction is a high anesthetic risk. To stabilize the patient, your veterinarian places the cat on an intravenous drip, which also helps bring the toxin levels in his bloodstream down.

If the bladder is exceedingly large, then she may use a fine needle to empty the bladder through the body wall. Then an anesthetic is given and a catheter inserted into the penile tip, and the urethra is flushed with copious amounts of saline that aim to dislodge the blockage and push it back into the bladder.

Once the obstruction is gone, the urinary catheter is stitched into place and left there for 2 to 3 days. This allows the bladder to recover and heal. If a trigger factor is identified, such as a urinary infection, then appropriate treatment is started.


Prevention includes lifestyle changes for the cat. Overweight cats are predisposed, so putting them on a diet helps reduce the risk.

Likewise, concentrated urine encourages crystal formation, so simple changes, such as switching from dry kibble to wet food, can help. If your cat is prone to develop certain sorts of urinary crystals, then feeding a prescription diet low in those minerals is essential.

Another big factor is encouraging the cat to drink, so offering large water bowls in every room, or even a pet drinking fountain, is an excellent idea.

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  • “Urinary tract disorders.” Little. The Cat: Clinical Medicine and Management. 935.
  • BSAVA Manual of Canine and Feline Nephrology. 2nd edition. Elliott & Grauer. Publisher: BSAVA Publications.


This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Oct. 13, 2018.

Dr. Pippa Elliott, BVMS, MRCVS

View posts by Dr. Pippa Elliott, BVMS, MRCVS
Dr. Pippa Elliott, BVMS, MRCVS, is a veterinarian with nearly 30 years of experience in companion animal practice. Dr. Elliott earned her Bachelor of Veterinary Medicine and Surgery from the University of Glasgow. She was also designated a Member of the Royal College of Veterinary Surgeons. Married with 2 grown-up kids, Dr. Elliott has a naughty puggle called Poggle, 3 cats and a bearded dragon.

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