Feline Urethral Obstruction: The Life-threatening 'Blocked Cat'

You may have noticed me harping on kitty litter husbandry for the past few weeks … it’s because one of the most common emergencies that I see in the ER is the feline urethral obstruction (FUO), otherwise known as the "blocked cat."

As an ER vet, I get frustrated with FUO for several reasons:

  • It’s pretty common, especially if you own a male cat
  • It’s expensive to treat
  • It’s often over- or mistreated by veterinarians
  • It sometimes results in the euthanasia of an otherwise normal, healthy cat.

An FUO is a life-threatening emergency which occurs when there is something physically blocking the urethra – in other words, the tube from the bladder to the tip of the penis is obstructed, preventing your cat from being able to urinate for days on end. Typically, the blockage is due to stones, crystals, mucous plugs, or grit or "sand" in the urethra. Left untreated, it can result in severe kidney failure, build up of toxins in the blood (e.g., electrolytes like potassium, which should normally be urinated out), and potentially fatal heart rhythms.

Personally, I think that kitty litter husbandry contributes to FUO; the dirtier the box, the less likely your cat wants to go in there. Then, those crystals clump together while the urine gets more concentrated, potentially resulting in an obstruction. Hence, my harping…

So, if you notice your cat showing the following signs, get him to a vet STAT:

  • Straining to urinate
  • Crying out/howling
  • Vomiting
  • Lying in the litter box
  • Making multiple trips to the box
  • Lack of urine clumps in the box
  • Excessive grooming

Other signs include: lethargy, small amounts of bloody urine, inability to urinate for more than twelve to eighteen hours, acting painful, or squatting to urinate in strange places (like in your tub, on your comforter, or in your large potted plant — "Hello! What do I have to do to get you to take me to a vet?"). All these signs are your cat’s way of telling you he needs help.

As an FYI, the signs of FUO are very similar to a sterile cystitis, which is often known as feline lower urinary tract disease (FLUTD). FLUTD does not require sedation and unblocking, so is less expensive to treat. That said, FUO and FLUTD both present similarly in cats.

When in doubt, bring your cat to a vet to cop a feel of the bladder; it’s the safest and easiest way to make sure he’s not blocked! In fact, some emergency clinics will even triage you away if you’re concerned, meaning they evaluate your cat in the lobby and decide whether or not you and your cat need to be seen. ("Is my cat blocked? No? I’m outta here!")

Finally, treatment. Veterinary care for an FUO includes sedation, unblocking (with a urinary catheter), IV fluids, blood work monitoring and pain medication. Unfortunately, cats often need to be hospitalized for several days before the kidney failure resolves. Typically, this runs you anywhere between $500-2,000 (and that’s uncomplicated!).

My pet peeve? When pet owners have financial constraints and can’t afford the whole gamut of expensive blood tests (which end up costing hundreds of dollars), only to have veterinarians who won’t work with them to find the least expensive way of treating their blocked cats. Personally, the most important test is the electrolyte potassium, as that’s the most life-threatening. If you have financial constraints, tell your vet — the whole gamut does not have to be performed.

Based on a great veterinary paper (yes, written by me) that came out in the Journal of Veterinary Emergency Critical Care,1,2 if your cat’s heart rate and temperature are normal, it’s highly unlikely that your cat has a life-threatening level of potassium … and can likely be unblocked and treated without expensive blood tests to boot.

So, heed my warnings. Keep your cat and your wallet healthy and avoid an FUO. Add some more water to your cat’s diet (via a cat water fountain or canned food). Scoop more. Be aware of your cat’s litter habits. The sooner you recognize FUO, the cheaper it is to treat!

Has your cat blocked before? What did you do to prevent it from happening again?

Dr. Justine Lee


1.    Lee JA, Drobatz KJ.  Historical and physical parameters as predictors of severe hyperkalemia in male cats with urethral obstruction.  J Vet Emerg Crit Care 2006;16(2):104-111.

2.    Lee JA, Drobatz KJ.  Characterization of the clinical characteristics, electrolytes, acid-base and renal parameters in male cats with urethral obstruction.  J Vet Emerg Crit Care Soc 2003;13(4):227-233.


Pic of the day: Angry cay wants water by Amanda

You Might Also Like