Urethral obstruction in cats

What is urethral obstruction?

You may have heard people talking about a cat becoming “blocked”; this refers to a condition where the urethra becomes blocked in some way which prevents the cat from urinating.

What causes the blockage?

There are many causes of a blocked urethra in cats, these include:

  • A “plug” in the urethra: a build-up of protein, cells, crystals and debris from the bladder than becomes lodged in the urethra.
  • A small stone (urolith), or several small stones from the bladder
  • Swelling or spasm of the urethra

Are any types of cat more at risk?

fat cat
It almost completely occurs in male cats, this is because their urethra is narrower and longer than a female cat, increasing the risk of it becoming blocked.

Other risk factors include:

  • Being overweight
  • Households with more than one cat
  • Inadequate water intake, usually associated with cats on dry food
  • Indoor only cats


How do I know if my cat is blocked?

The most common signs you may see are:

  • Repeated attempts to urinate with no success
  • Discomfort (possibly vocalising) when trying to urinate. May also seem painful when pressing on the abdomen.
  • Agitation and possible vomiting.

If you notice any of these signs then contact your vet immediately as this is an emergency situation.

Some cats will display cystitis symptoms for a few days before becoming obstructed. These signs include more frequent urination and passing blood in the urine.

What happens if this condition if left untreated?

Urethral obstruction is a potential fatal condition if left untreated. The inability to urinate can lead to acute kidney failure and dangerously high level of potassium in the blood which may result in irregular heart rhythms and eventually cardiac arrest. This can happen in just 2-3 days if not managed promptly.

What will my vet do?

The vet will examine your cat and confirm whether or not an obstruction is suspected. This diagnosis is made on the basis of the appropriate symptoms together with a large and painful bladder.

Following diagnosis the vet will request to admit your cat for treatment. This will involve relieving of the obstruction by passing a urinary catheter usually under sedation or general anaesthetic. We will then flush the bladder with sterile saline to remove any debris in the bladder. Sometimes the catheter will need to stay in for a few days to maintain good urine flow.

Depending on the duration of the blockage and how sick your cat is, we may also advise blood testing to check kidney function and potassium levels. Some cats require hospitalisation for a few days on a drip to correct these abnormalities.

An x-ray or ultrasound examination may need to be carried out to determine the cause of the obstruction and often a urine sample will be examined under the microscope to look for evidence of crystals, a major cause of obstruction. Identifying the cause of the obstruction allows us to instigate an appropriate treatment plan to try and prevent recurrence.

What happens when my cat comes homes?

It is important to try and prevent obstruction occuring again, anti-inflammatory drugs may be given initially to settle down any swelling in the urethra.

Cats in which the blockage was caused by stones or crystals in the urethra and bladder, may be changes to a diet that will help to prevent the formation of stones in the future. We may also advise weight loss, stress reduction and increased water intake as these things may all help to reduce the risk of recurrence.  Your vet will advise how to go about making these changes.

In somes cats despite all these measures the blockage may reoccur and surgical options may need to consider. Fortunately these cases are rarer and most can be managed medically.


Pool House Vets