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A Guide To Urethral Obstruction in Cats

Aimee Labbate
  • Aimee Labbate

  • RCVS: 700039


Urethral obstruction, or a blocked bladder, is a life-threatening emergency where there is a blockage of the lower portion of the urinary tract (the urethra). This means that the cat is unable to urinate and hence the bladder becomes very large, meaning it could rupture, and there is back pressure affecting the kidneys. It is far more common in male cats, as the urethra in female cats is shorter and wider and therefore less prone to blockage. It also occurs more commonly in young to middle-age and being overweight is known to be a risk factor.

What causes a blocked bladder in cats?

Several factors usually contribute to the urethral obstruction in a cat, these include:

  • A stone – these can form in the bladder and they can then get stuck in the urethra when they try to pass.
  • A urethral ‘plug’ – this tends to be made up of an accumulation of cells, protein, crystals and debris and it can lodge in the urethra.
  • Urethral spasm and swelling – inflammation in the urethra (possible due to a stone or plug) can cause swelling and spasm of the urethral muscles, further contributing to the blockage.

What are the symptoms of a blocked bladder in cats?

The typical symptoms of an obstruction include:

  • Failed attempts at urination
  • Going in and out of the tray multiple times
  • Straining to urinate (some people think their cat is constipated)
  • Crying when trying to urinate
  • Blood in the urine
  • Licking at the penis
  • Lethargy
  • Loss of appetite
  • Vomiting

If you have any concerns that your cat may have a blocked bladder then please contact your vet ASAP, at it is an emergency and can prove rapidly fatal.

How is a urethral obstruction diagnosed in a cat?

A blocked bladder is normally easy to diagnose by the vet gently feeling your cat’s abdomen. If there is a urethral obstruction then the bladder will be full of urine. There may also be small amounts of blood around the penis.

How is a urethral obstruction in a cat treated?

The treatment involves stabilising the cat and relieving the obstruction. The vet will take a blood sample to check for evidence of damage to the kidneys and to check the electrolyte levels, as a very high potassium level is common in these cases and can affect the heart. Your cat will be placed on a drip to help to stabilise them. They will then be sedated or anaesthetised to allow the placement of a urinary catheter to relieve the obstruction. The bladder will then be flushed with sterile saline to wash away as much debris as possible.

Imaging (x-rays and/or ultrasound) will also usually be performed to check for the presence of any bladder stones, as sometimes these cannot be flushed out and may need to be removed surgically.

Medication is given to make the cat feel comfortable and to help with the urethral spasm. Most cats will need to stay in the hospital for a couple of days while the urinary catheter is left in place, to allow further blood and debris to drain from the bladder, before it is removed. This helps to reduce the risk of the cat re-blocking, although unfortunately this is always a possibility.

Will my cat recover from a blocked bladder?

While a urethral obstruction is a serious and life-threatening emergency, with prompt veterinary treatment most cats make a full recovery.  There is the risk that they may block again, however, so following the management steps below is important to reduce this risk as much as possible.

Where a cat experiences recurrent blockages, or where the blockage is very severe and cannot be cleared, there is an operation that can be performed called a perineal urethrostomy (PU). This involves increasing the size of the urethral opening, thereby reducing the risk of a blockage forming. While this is a major operation, it can be very successful in these challenging cases.

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What can I do to help prevent a blocked bladder in a cat?

Long term management is key to reduce the risk of the cat having suffering from another urethral obstruction. Many cats that suffer from urethral obstruction are thought to have underlying feline idiopathic cystitis (FIC) – you can read more about this condition here. Therefore, the management strategies that are important with FIC are also important for urethral obstruction, these include:

  1. Dietary modification
  • Increasing water intake appears to be beneficial, as it results in a more dilute urine that is less irritant to the bladder lining and where crystals (and therefore stones) are less likely to form. This can be achieved by feeding a wet rather than dry diet or adding water to the biscuits if your cat will not eat wet food. You could also try using a water fountain, as some cats like to drink from a moving stream of water (hence some like to drink from the tap!). These are available from our shop.
  • Some specialised veterinary therapeutic diets are designed to help with FIC. They contain ingredients such as polyunsaturated fatty acids which may help to reduce bladder inflammation in FIC, as well as anti-stress products and additives that can help to increase water intake. You can find a couple of these diets in our shop by following this link.
  • Some cats can be fussy and changing diets can therefore be hard. Do not make any sudden changes, gradually increasing the amount of the new diet over the course of at least several days, if not a few weeks for very fussy cats. Warming the food gently to around 30˚C can help to increase the palatability.
  1. Environmental modification
  • Be careful with your choice of water bowls. Having multiple bowls and using ones that are wide and shallow that do not irritate your cat’s whiskers can help to increase water intake. Also using glass or ceramic bowls is recommended, as metal and plastic bowls can lead to a bad taste in the water (this may explain why your cat loves to drink out of your glass of water rather than their own bowl!).
  • Ensure you have enough litter trays and that they are kept clean. The rule of thumb is that you should have the same number of litter trays as you do cats, plus another one. Even if your cat normally toilets outside it is a good idea to have a litter tray available, in case they are stressed by another cat outside and it therefore gives them another option. Position them in quiet spots where they are not disturbed.
  • Provide environmental enrichment such as scratching posts and shelves to climb onto.
  1. Reducing stress
  • Try to identify any potential stressors and avoid or minimise them where possible.
  • Conflict between cats is probably the most common cause of FIC and this conflict is not always obvious. It can be between cats in the same household or those outside.
  • Provide hiding places such as a box or enclosed bed where they feel safe.
  • Pheromone therapy like a Feliway diffuser can be helpful for some cats as it can make them feel safe and secure. We have these in our shop so please follow this link to have a look.
  1. Drug therapy
  • Anti-inflammatory pain relief such as Metacam is often used during flare ups to make the cat feel more comfortable, and to help reduce inflammation in the bladder.
  • Bladder supplements such as Cystaid Plus (also available from our shop) can help to soothe the bladder lining.

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