Feline urologic syndrome (FUS) and blockages are conditions we see often. They’re serious and can be fatal without quick treatment. Let’s look at what causes the disease, symptoms to watch for, and how we battle it.

Symptoms of Disease or Blockage

Cats can’t say when they have pain or illness. They rely on us to recognize when something isn’t right. Keep an eye out for the following symptoms, which indicate problems in the urinary tract:

  • Straining to urinate, with ability to pass little or no urine

Note: if your cat is unable to urinate, seek help from a veterinarian immediately. This is a sign of complete blockage and is an emergency.

  • Pollakiuria (frequent urination or attempted urination)
  • Periuria (urinating outside the litter pan)
  • Hematuria (blood in the urine)
  • Excessive licking of the genital area
  • Crying out due to pain as the bladder becomes enlarged
  • Vomiting
  • Inabilityto sit or stand due to weakness

If your cat displays symptoms of FUS, contact your veterinarian right away. It doesn’t take long for it to become life-threatening. An examination is necessary to check for blockages.


Determining the underlying cause(s) of FUS requires one or more of the following tests:

  • A Physical exam and client interview are the first steps. The exam usually reveals if a cat suffers from obstruction. A full, painful bladder indicates obstruction. An empty, small bladder indicates non-obstruction. However, a small bladder doesn’t mean that obstruction won’t occur. A conversation about a cat’s home behavior also provides important clues.
  • A urinalysis screens for bacteria, crystals, blood cells and checks the pH of the urine.
  • Radiographs and ultrasounds of the bladder and urethra (the tube that passes urine from the bladder to outside the body) help identify the presence and position of stones and any thickening of the bladder wall.


Any of several culprits can cause disease and blockages including tumors, stones, and cystitis. While tumors are rare, they’re possible. Cystitis (inflammation of the bladder) is common and comes in various forms

Bacterial cystitis (urinary tract infection) is rare. When this does happen, it’s more likely to occur in older cats. They have a higher risk of infection than younger cats. This is due to higher instances of diabetes and kidney disease, which reduce acid in urine.

Feline idiopathic cystitis (FIC) accounts for the majority (85%) of FUS cases. With this, cats display the symptoms of FUS, but all tests come back with no clear cause. Sometimes, an x-ray will show a thickened bladder wall. The symptoms typically relieve themselves within days but often recur unpredictably.

Feline interstitial cystitis is the formation of sharp crystals in the bladder. Even the smallest crystals cause inflammation and pain when they rub on the bladder wall. Struvite crystals are caused by several factors. The pH of urine, amount of magnesium and phosphorous emitted into the urine, length of time urine stays in the bladder, and concentration of the urine all contribute.

Stones, called uroliths, often occur when crystals become a mass. Stones made from calcium oxalate sometimes pass in females. In males, they must be removed with surgery due to the size of the urethra. Unlike struvite crystals, Calcium oxalate stones can’t dissolve. These occur because of acidic pH levels in the urine and the amount of calcium passed into the urine.

Note: Stones, crystals, and inflammation can all cause partial and complete blockages.


The effects FUS have on cats are scary and can be severe:

  • Blockages of the urethra leave cats able to pass little or no urine. As the bladder fills, it becomes enlarged and painful. The kidneys can’t filter toxins from the blood and balance electrolytes. This eventually leads to heart failure and death.
  • Another possibility is a ruptured bladder. If urine exceeds the capacity of the bladder, the bladder will rupture. Urine will seep into the abdominal cavity. Left untreated, death can occur within a matter of days.


Treatment of FUS depends on what cause(s) the diagnosis reveals:

  • A flush of sterile fluid through the urethra can clear some blockages.
  • A prescription diet may dissolve struvite crystals if they are small enough.
  • Surgery to remove stones, crystals, or tumors may be necessary.
  • In the rare case of bacterial cystitis, antibiotics will resolve the issue. Many owners request prescriptions for antibiotics, thinking they will cure any urinary disease. But antibiotics only work for bacteria; and bacteria are rarely the cause of urinary disease.
  • Pain medication helps keep cats comfortable while undergoing treatment and recovery.

Following diagnosis and treatment, obstructed (and sometimes unobstructed) cats need to stay in hospital for one to three days. This is for an IV treatment to decrease toxins and balance electrolytes. It’s also to monitor the function of the urinary tract and watch for re-blocking.


Several preventative measures can reduce the risk of occurrence or recurrence of FUS and blockages:

  • Your veterinarian will talk with you about specific diet changes. This may include prescription food. Certain foods have low levels of magnesium and ash, and elevated salt levels that encourage drinking. More drinking means more urinating; and that reduces the time crystals have to form.
  • Always provide plenty of fresh, clean water for your cat.
  • Keep litter boxes clean and in quiet, safe spots.
  • Pets thrive on routine. It helps reduce stress, which is also important in the prevention of disease.
  • Other effective stress reducers include prescription calming food and use of Feliway pheromones.

Talk with your veterinarian about a specific plan for your cat’s recovery from and prevention of disease. Follow the plan and schedule check-ups. With exception of feline idiopathic cystitis, FUS rarely comes back. This is, of course, dependent on proper treatment and prevention measures.

Feline urologic syndrome and blockages are common in cats. They cause pain, suffering, and sometimes death. Always monitor your cat’s behavior. Get medical help right away if you notice any signs of FUS. With quick diagnosis and proper treatment, we can work to solve the issue and prevent recurrence.

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