Did you say 'fluted'?

If you've ever brought your cat to a vet for possible cystitis, you might have been told your cat has something called fluted. That's actually FLUTD, which stands for feline lower urinary tract disease.

FLUTD isn't a specific disease itself. It's an umbrella term that covers a range of conditions affecting the lower urinary tract (ie the bladder and urethra) of cats.

The different conditions all have such similar symptoms and signs that it's difficult (often impossible) to tell which one your cat has without doing further investigations.


What are the signs of FLUTD?

The common signs of FLUTD are:

  • difficulty passing urine (dysuria) – your cat may appear to strain to pass urine and may even cry out in pain

  • frequently passing or trying to pass urine (pollakiuria) – if the bladder wall is inflamed and swollen, this creates a stretch sensation much like a full bladder does, hence your cat has a drive to keep trying to empty the bladder, even though it might be empty

  • blood in the urine (haematuria) – sometimes this is visible with the naked eye (as pink urine or small clots), or it may only be detected on urinalysis

  • urinating in places other than the litter tray (periuria) – this can be because of urge (your cat can't make it to the litter tray) or pain ('It hurts when I go into the litter tray so I'll go somewhere else')

  • licking around the vulva or prepuce

  • not being able to pass urine (stranguria) – this is much more common in males than females because they have longer and narrower urethras that become blocked more easily. This one is an emergency and needs urgent treatment

Not all cats will have all signs. Some may only have one.


What are the causes of FLUTD?

Some of the common causes of FLUTD symptoms are:


Bacterial infections 

Bladder infections (bacterial cystitis) are very common in other species, but actually not that common in cats. In fact, they're rare in cats under 10 years of age. Most of the cases we do see are in older cats, particularly older female cats. Bacterial infections account for up to 50% of the cases of FLUTD in older cats but 1–5% of cases in cats under 10.

This is why it's unusual for us to treat younger cats with FLUTD symptoms with antibiotics without doing a urine test.


Bladder stones

Cats get two main sorts of stones (uroliths): struvite (magnesium ammonium phosphate) and calcium oxalate. Although crystals containing these components are extremely common (struvite more than calcium), stones only make up around 10–15% of all cases of FLUTD.

Note that crystals do not cause signs of FLUTD. They can contribute to urethral plugs (see below) and they can aggregate together to form stones, but in the crystal form, they don't irritate the bladder. I know, you've probably been told they do. Crystals are not the only cause of bladder stone formation.


Urethral plugs

These are the main cause of urethral obstruction in male cats. The plug is an accumulation of protein, cells, debris and crystals that forms in the bladder and then travels down the urethra during urination. If the plug is wider than any part of the urethra it becomes stuck and prevents further urine flow. The most common spot for plugs to lodge is the penis.

Small stones can also cause blockages. Sometimes there is no physical blockage, rather the urethra muscles go into severe spasm and effectively close it off.


Feline idiopathic cystitis (FIC)

Idiopathic cystitis means bladder inflammation of an unknown cause. It accounts for 60–70% of all cases of FLUTD. Now, there's no test for it. It's basically diagnosed when we can't find another cause. 

FIC has several similarities to interstitial cystitis in people. Stress or an abnormal response to stress appears to be involved in triggering FIC.

We go into more detail about FIC in Urinary problems – Part 2.

Less common causes of FLUTD include anatomical defects (eg scarring of the urethra) and tumours in the bladder or urethra.


What investigations are done with FLUTD?

For a first presentation with mild symptoms, we might not do any investigations. For cats that are obstructed, we will often need to start life-saving treatment before investigations are done.

The things we might suggest include:

  • urine testing (urinalysis) – typically this includes a dipstick test, a USG (the concentration of the urine) and looking at the urine under a microscope. We may send the urine away for 'culture and sensitivity' if an infection is suspected. A urine sample is usually obtained by placing a fine needle into the bladder, which allows us to get an uncontaminated sample

  • ultrasound – this enables us to look at both the bladder wall and the contents inside the bladder. Most ultrasounds can be done without sedation

  • X-rays – some stones show up well on X-ray and we can also use a dye (contrast) to look for damage to the urethra and bladder. Contrast studies require a general anaesthetic.

If we find suspicious masses in the bladder or urethra, we may then recommend a biopsy. This is usually done surgically.


How is FLUTD treated?

Treatment for FLUTD depends on the underlying cause. But whatever the cause, increasing water intake is usually a good idea. Making a cat drink more water sounds tricky, but it can be done by getting a drinking fountain (lots of cats like running water), putting water bowls in several spots and/or swapping to wet food. 


Bacterial infections

These are treated with antibiotics. For first time infections, we are likely to use a broad spectrum antibiotic that works against the usual suspects (eg faecal bacteria). If your cat has recurrent problems or the antibiotics don't work quickly to resolve the symptoms, we'll send the urine away so that lab can grow the bacteria and see what they're sensitive to.


Bladder stones

There are two main ways to get rid of stones. The most common is via surgery. The other is by using a special diet designed to dissolve the stones. Not all stones can be dissolved and it can take several months to dissolve the ones that can (depending on the size). 

After surgery, a prescription diet is usually recommended to prevent recurrence of stones. Wet foods increase water intake and help prevent stone reforming too.


Urethral plugs

Urethral plugs need to be removed urgently. If your cat can't pass urine, he can develop acute renal failure and build up enough potassium to cause his heart to stop in 2–3 days.

Having a urethral plug is very painful, so in most cases we need to remove it under anaesthesia. The plug is usually dislodged by placing a fine catheter into the urethra of the penis and flushing it back into the bladder. The urine is then drained from the bladder. As the urethra tends to be both swollen and prone to spasm due to the plug, your cat can have difficulty passing urine for a few days. We use medication to help this, but frequently we leave the catheter in place for a day or two until the area has settled down.

As with bladder stones, to prevent further urethral plugs, we try to increase water intake (with wet food). If crystals have contributed to the plug, then a diet to reduce formation of these might be recommended. The crystals won't have caused the plug, so it's possible for plugs to recur even on special diets.

Unfortunately, we have no single treatment that is guaranteed to prevent further plugs.


Feline idiopathic cystitis

Treatment for FIC is complex and evolving. Because the disease process is not yet fully understood, we also don't yet have reliable treatments. Medications are often given in an attempt to reduce pain, and they may seem to work, but as the condition spontaneously resolves, it's hard to say whether they are truly having an effect.

Like with the other causes of FLUTD, encouraging more water intake is recommended. The more dilute the urine, the less it can irritate the bladder lining.

As stress plays a role in triggering FIC, it's worth looking at ways to reduce this with things to 'enrich' your cat's environment and trying something like Feliway®, which is a facial pheromone.

While many cats have episode after episode of FIC, the good news is that they generally grow out of it (eventually).


FLUTD is extremely common. It can also be frustrating when the symptoms come back again and again. While we don't have a magical cure-all, we can help.