Blocked Cat

Blocked Cat

What is a blocked cat?

The term “blocked cat” refers to a condition in which the cat’s urethra (the tube which carries urine from the bladder to the outside) becomes blocked so that the cat cannot pass urine. The condition is more common in male cats than females.

This is a life threatening condition and urgent veterinary assistance should be sought



What are the signs of urethral blockage?

Typical signs noticed by owners are very similar to other urinary tract conditions (see “cystitis and lower urinary tract disease”)

These signs include:

  • Increased frequency and urgency of urination attempts.
  • Licking at ‘back end’
  • Yowling, especially when trying to pass urine
  • Difficulty in urinating (straining persistently without producing any urine), this can look like constipation.


As the cat cannot expel urine the bladder fills up and becomes hard and painful, blocked cats are often crying in pain. The bladder can become so full that the pressure flows back to the kidneys and prevents the kidneys from functioning correctly. This leads to massive electrolyte imbalances which cause:

  • Bradycardia (very slow heart beat)
  • Depression
  • Vomiting
  • Not eating
  • Weakness/collapse
  • Muscle stiffness
  • Hypothermia
  • Hyperpnoea (breathing fast)
  • Coma and death

What causes urethral blockage?

The urethra can become blocked by substances which accumulate in the bladder. The most common components of these ‘urethral plugs’ are one, or a combination of the following:

  • Bladder stones (uroliths): These are made up of many tiny ‘crystals’, there are 2 main types of bladder crystal, ‘struvite’ and ‘calcium oxylate’. Struvite can be dissolved using special diets whereas Oxylate won’t dissolve and, if it forms into stones, needs to be surgically removed.
  • Protein: this is thought to build up in the bladder as a result of inflammation
  • Cells: White blood cells and cells from the bladder wall

Neoplasia (tumour) can also cause urethral obstruction; a tumour growing either inside the bladder, blocking the urethral opening, or outside the bladder, squashing the urethra, can block the passage of urine.

Some cats can be ‘blocked’ as a result of very painful cystitis, their urethra goes into spasm and constricts so tightly that urine cannot be expelled

How is this condition diagnosed?

Often the history from the owners is enough to cause the vet to suspect either lower urinary tract inflammation, or urethral blockage.

Abdominal palpation (feeling the belly) is usually diagnostic as the vet will be able to feel a large, hard and painful bladder. The tip of the penis may be dark red-purple in colour and may be swollen.

What is the treatment?

Treatment involves a sedative or a general anaesthetic; the vet will insert a urinary catheter into the urethra so that the urine can be drained from the bladder. This can sometimes be tricky if the blockage is difficult to clear and is quite a delicate procedure. Usually the vet will then flush the bladder out by syringing fluid through the catheter and letting it drain out. This acts to remove or dilute any debris or crystals still present in the bladder.

The urinary catheter stays in for a couple of days and the cat remains on a drip so that the urethra can repair and the bladder continues to be flushed.

The catheter is then removed and the cat will then usually stay in the hospital until it urinates by itself.

If the cat is very sick when it comes into the hospital, and a blood test confirms major electrolyte imbalances, it may not be well enough to undergo sedation or general anaesthetic. In this case the vet will need to give medication to try to stabilise the cat before going on to unblock the bladder.

Some vets will drain the bladder by inserting a needle through the cat’s side into the bladder and drawing out the urine with a syringe (cystocentesis).

How can it be prevented?

It’s impossible to completely prevent this condition from occurring, there are numerous supplements and diets designed to help reduce the incidence of urinary tract problems in cats, but encouraging high fluid intake is equally if not more important. Feeding a wet diet, adding water to food, adding flavourings to water and providing items like a water fountain are some ideas on how to increase your cat’s fluid intake.

Ensuring your cat is a good weight (not obese) and is active can also help maintain good urinary tract health.


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