Urinary obstruction

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What is it?

This condition is also known as the ‘blocked cat’. It happens when a cat’s urethra, the tube carrying urine from the bladder to the outside, becomes blocked. Male neutered cats are especially vulnerable to this because their urethra is very long and narrow where it runs through the penis. Under certain conditions, such as a spasm in the urethra, the presence of bladder stones, when the cat is stressed, or as a result of an injury, the urethra may be blocked by a plug of mucus and urine crystals, and the cat cannot urinate.

While female cats can develop a blockage, it is much rarer than in males, because the urethra is shorter and wider.

Why is it important?

Urinary obstruction is a life threatening emergency.

What is the risk?

When the cat cannot urinate, there is a serious risk that their kidneys will be damaged. Urine is one of the ways the body removes harmful waste products. If these waste products cannot be removed through passing urine, they accumulate and may poison the kidneys. Too much urine trapped in the body means that the levels of a salt called potassium increase in the blood. A high level of potassium can affect the heart rhythm, meaning that the cat is at high risk of heart failure. Urinary obstruction is a very painful situation. Ultimately the bladder can rupture inside the cat. Rupture of the bladder will cause severe pain, shock and collapse. Ultimately, a blocked bladder will always be fatal if the blockage cannot be relieved.

What happens to the cat?

Signs of a blocked bladder:

  • Straining to pass urine, sometimes with spots of blood. Sometimes this behaviour may be mistaken for constipation.
  • Going in and out of their litter tray.
  • Passing urine outside the litter tray, or around the house.
  • Vomiting and not eating.
  • Licking their genital area excessively.
  • Crying out in pain when trying to pass urine.
  • A blocked bladder will become dangerously full within hours of a blockage occurring. If left untreated, the cat may go into a coma and die within 24-48 hours.

    How does the vet know what is going on?

    The vet will want to talk to the owner to find out more about how the cat has been behaving at home. They will then usually examine the cat and feel the size of the bladder. If the cat is blocked, the bladder can become the size of a small orange and is often very firm and painful when felt. If urine cannot pass from the bladder with gentle pressure, then the cat is blocked. They will take great care when feeling the bladder as too much pressure may cause it to burst. Sometimes a plug of mucus and debris can be seen at the tip of the penis. The cat may be showing signs of shock and extreme pain by this point.

    What can be done?

  • Immediate admission to the clinic, or referral to a better equipped facility if this is not possible. They may need to stay as an in-patient for several days.
  • Blood tests to check the cat’s kidney function and blood potassium level.
  • Fluid therapy to correct shock, correction of blood potassium levels (if required).
  • Pain relief is extremely important.
  • Once the cat is stable after fluid therapy and pain relief, a general anaesthetic is given for the placement of a urinary catheter, which is placed under sterile conditions. The vet will usually collect urine at this point to check for crystals or signs of infection, both of which increase the risk of a urinary blockage and may require ongoing management. The catheter may be stitched in place for a few days, sometimes with a collection bag attached, to ensure the urethra can heal properly. In almost all cases, an Elizabethan collar will be used to try and reduce the risk of the cat pulling out their catheter.
  • Sometimes, if the urethra is severely damaged and the catheter cannot be placed, a procedure called a perineal urethrostomy may be required. This creates a new orifice for the cat to urinate out of, bypassing the blockage.
  • Antibiotics may be used if the catheter stays in for several days, or if there is proven infection - this is rare in cats under 8 years of age.
  • It may be appropriate to take X-rays (radiographs) to look for underlying causes, for example if a bladder tumour or bladder stone is suspected.
  • Once recovered from the anaesthetic, the patient is encouraged to eat, often wet food to increase fluid intake.

  • How can I protect my pet?

    Be aware of the signs of urinary blockage and seek immediate veterinary help.

  • Stress is a big risk factor for urinary blockage. Management of stress at home can include pheromone diffusers (such as Feliway), and ensuring that the cat has lots of quiet, safe hiding places.
  • A diet that prevents the formation of crystals may be appropriate (usually for life).
  • Wet food may help to increase fluid intake. Some cats may benefit from a water fountain drinking system.
  • Multiple litter trays in a multi cat household to avoid overcrowding and stress.
  • There are significant cost considerations for treating a patient with a blocked bladder. 11-41% of cases will have another episode of obstruction.

    If the obstruction cannot be relieved; or keeps reoccuring, it may sadly be necessary to consider euthanasia, rather than leave the cat suffering.