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Urethral Obstruction aka Blocked Tomcat

Male cats have a tendency to develop stones and/or debris in their urine that can cause an obstruction of the urethra. Crystals, small stones (called calculi), mucus or inflammatory material form in the kidneys and are passed down into the bladder.  When urinating, this material may cause an obstruction that prevents urine from exiting the body. An obstructed urethra can become a painful and dangerous condition in a very short period of time.  A complete blockage can cause irreversible damage to the kidneys and can even cause death.  The cause of the inflammatory materials and stone formation it not well understood, though viral infections and diet may play a role. Other causes such as cancer, previous injury causing scarring, and trauma are also reported.

cat austin

Clinical Signs

Signs of a urethral obstruction include:

  • Using the litter box often,
  • Straining to urinate with no or little resulting urine,
  • Unusual accidents in the house,
  • Leakage of urine,
  • Constantly licking his bottom,
  • Vocalizing more than usual, especially when using the litter box,
  • Depression,
  • Pain,
  • Weakness,
  • Lack of appetite,
  • Dehydration (lift up the scruff; if it does not return to normal quickly, your kitty is dehydrated),
  • Collapse.

The most obvious signs we see are straining to urinate or accidents in the house.  Some cat owners may think these behaviors indicate constipation.  While that is a possibility, it is safer to assume an obstruction since the condition can become life-threatening very quickly.  It is essential to seek veterinary attention if you notice any of these signs your cat’s behavior, especially if he is male.


Treating a blocked cat typically involves, bloodwork, sedation, relieving the urethral blockage, emptying the bladder,  IV fluids and medications to deal with the biochemical abnormalities that have developed.  This is typically done by placing a catheter through the urethra and leaving it in place until the bladder has had a chance to remain empty and recover.  There is a possibility that the cat will obstruct again soon after the catheter is removed.  Most cats will remain hospitalized to allow close monitoring.

Often unblocking the cat is successful and they can return to normal function after hospitalization and IV fluid.  However, sometimes blockage is a reoccurring problem or the obstruction is too large to remove.  If the cat never regains the ability to urinate normally, surgery can be performed to create a hole in the urethra above the blockage, allowing urine to be expelled.  This surgery is called a perineal ureterostomy (PU).


Unfortunately, cats that have experienced a urethral obstruction are at a higher than average risk for developing this problem again.  Diet is a key component in decreasing the likelihood of an obstruction if crystals or stones caused the blockage.  Drinking plenty of water, exercise and adjustments in their diet will help.  In addition, wet food that is low in magnesium seems to decrease the formation of crystals and provide increased hydration to flush the kidneys and remove debris.  Cat food producers have developed specialized diets to reduce the risk of obstruction.  Ask your family veterinarian for food recommendations that may work for your cat.  Because many cat owners feed this type of diet to their male cats, urethral obstruction is less common than it used to be.