Difficulty passing urine is a common reason to visit the clinic. Urine is produced by the kidneys. Urine removes fluids, salts, excess dietary protein and protein waste from the body. The urine passes along tubes (ureters) to the bladder where it is stored. When the cat urinates, the urine flows along the narrow tube to the outside (the urethra). This flow is controlled by relaxing and contracting muscles. If the urine cannot be passed it will quickly build up and make your cat very ill.

This system normally works very smoothly but problems can occur two ways.

The result is the same, the cat goes to the litter tray very often but passes nothing or only a few drops. You will see that your cat has difficulty passing urine. This is an urgent reason to visit Hung Hom Veterinary Clinic.

Vets call the problem FLUTD, Feline Lower Urinary Tract Disease. FUS or Feline Urologic Syndrome is an older name. In many cases these signs will settle down over a few days and the problem will appear to go away, only to recur quite soon after.

In some cases however the problem is much more serious. If there is an actual blockage and the urine cannot be passed, the urine will build up in the bladder and put pressure on the kidneys. This is usually seen in male cats. The cat will become dull and inappetant as he develops acute kidney failure. He may vomit and be very weak. If ignored, this will be fatal.

There are many different possible causes of FLUTD. It is not been possible to find one single cause. FLUTD is not a single disease; it is a name for a group of problems that have cause difficulty passing urine and distress.

Most cases of FLUTD have no identified cause; they are idiopathic (unknown cause). Many cases are related to stress or anxiety in the cat. It might seem that cats live a relaxed life, but things happen which can cause them great stress and anxiety.

Anything which upsets the cat can result in an irritable bladder and cause the cat to need to visit the litter tray very frequently

If the cat does not take in enough water the urine will be highly concentrated. This means that salts in the urine can form small crystals. The crystals can irritate the bladder and cause the signs of FLUTD. The crystals are most likely to form if the acid level of the diet is not normal or there is too much magnesium in the diet.

The food that the cat eats will greatly affect the magnesium and acid levels and the concentration of the urine. If a cat eats dry food only it will not take much water in when it eats compared to a cat on wet or can foods. A dry food diet will tend to promote concentrated urine which leads to crystals forming.

The lining of the bladder will normally produce some mucus to help protect it from the urine. If the bladder is chronically irritated it may produce excess thick mucus. Crystals may become trapped in the mucus forming a semi solid mass. If this gets into the urethra it may form a plug or obstruction at a narrow point. This will cause signs of FLUTD.

It was once thought that bladder problems in cats were caused by bacterial infections. In fact this is only a rare cause of FLUTD in young cats. Bacterial infections can occur, more often in older cats with more dilute urine, or in combination with other problems. Infections can change urine acid levels and lead to crystal formation and plugs.

Cancer of the urethra, bladder or even prostate is a rare cause of FLUTD in older cats. A growth will lead to inflammation in the bladder, bleeding and signs of FLUTD.

Life is not simple! There is nothing to stop a cat getting a combination of these problems. One problem can lead to another, so the cause of FLUTD in many cats can be difficult to understand.