Feline Lower Urinary Tract Disease (FLUTD)

Feline Lower Urinary Tract Disease (FLUTD)

To ascertain the best possible care for our cats we all vigorously fight to keep them healthy, well-fed, warm, groomed and happily spoiled. However, in order to protect our purrfect companions from diverse health-threatening factors, we must possess knowledge and skills to recognize an issue and assert preventative measurements and/or treatments. One such threat, affecting about 0.5-1% of feline population, is feline lower urinary tract disease (FLUTD).

What is feline lower urinary tract disease (FLUTD)?

Feline lower urinary tract disease (FLUTD) is a group of conditions that affect feline bladder and urethra. There is a variety of different conditions associated with feline lower urinary tract such as, inflammation of the bladder (cystitis) or urethra, urethra obstruction (partial or complete) and formation of urinary crystals in the bladder (crystalluria or urolithiasis).


There is a number of different causes for FLUTD of which some of more common ones include:

1. Urinary stones. Urinary stones or uroliths are mineral structures that can form in feline bladder, ureters, urethra and even kidneys. Uroliths are the underlying cause for about 15-20% of all FLUTD cases. The vast majority of uroliths are calcium oxalates or magnesium ammonium phosphates (struvites). While these two types of stones account for 80-90% of all uroliths, other mineral formations can be observed too (i.e. ammonium urate, uric acid, calcium phosphate and cystine uroliths). Calcium oxalate stones need to be removed surgically, while struvite stones can be addressed with specifically adapted stone-dissolving diet.

cute orange tabby cat sleeping in a white cat cave

2. Urinary infections. Bacterial, fungal, parasitic or viral infections can all lead to signs of FLUTD. Bacterial infection of the bladder, bacterial cystitis is a common cause of lower urinary tract diseases in many animals, but not in cats. While bacterial infections occur more commonly than other types of infections, they are still relatively rare among felines.

3. Urethral obstruction. Partial or complete obstruction of urethra is one of the most serious problems affecting lower urinary tract. This problem occurs due to an accumulation of urinal crystals, cells, proteins and debris into plugs that cannot be passed. The urethral obstruction can also occur due to lodging of bladder stones or severe muscle spasms. The problem is most commonly observed among male cats as they have longer and narrower urethras. Note: Urethral obstruction is a serious medical emergency which requires immediate veterinary attention. This is because the obstruction of urethra can lead to renal failure and uremia. If left untreated, such condition leads to death in less than 72 hours.

4. Feline idiopathic cystitis (FIC). Feline idiopathic cystitis (FIC) or feline interstitial cystitis is an inflammatory condition affecting the bladder. This disease is not fully understood and is usually diagnosed by exclusion of any other possible diseases of similar signs. The exact causes are uncertain, and it is thought that the combination of low water intake and increased permeability of the bladder wall lie in the roots of it. Cats suffering from FIC excrete lower levels of GP-51, a protein that lines the bladder and prevents bacterial adherence. This leaves the bladder lining of the affected cats exposed. Urinal substances can therefore contact neurons in the bladder which, when stimulated, cause pelvic pain. Their prolonged stimulation causes chronic inflammation which further increases the vascular permeability of the bladder.

5. Other causes. Although less commonly, FLUTD can also be caused by a variety of other conditions such as tumors, diabetes, hyperthyroidism, congenital abnormalities and injuries. Diet, obesity and irregular exercise may also increase the risk of developing FLUTD.

Symptoms and diagnosis

beautiful long-haired beige cat with green eyes

Cats with any type of FLUTD often have difficulty or pain when urinating and increased frequency of urination. They may show signs such as excessive licking, presence of blood in the urine and urinating outside the litter box (often on cold surfaces). Note: In cases of urethral obstruction, while the cat will show similar signs and obvious state of distress, there will be little or no urine passed!

Considering the variety of causes, FLUTD can be difficult to diagnose. Diagnostic methods include physical examination, urinalysis (pH, presence of crystals, blood, inflammation and infection), urine culture, blood analysis, x-rays, ultrasound and biopsies.

Treatment and prevention

1. Urinary stones. The fastest way to resolve the urinary stones is to remove them surgically. This way of treatment is called cystotomy. After the stones have been surgically removed, they are usually sent to the lab for further analysis. A less invasive way of resolving the stones is cystoscopy which involves an instrument, cystoscope, which removes the stones from the bladder through the urethra. This method, however, can be used to treat female cats diagnosed with small stones. A third possible way to treat smaller stones is with the technique called voiding urohydropropulsion. In this method, the patient is sedated and positioned vertically, and the full bladder is manually expressed under pressure. This way stones are passed that might have otherwise stayed in the bladder.

Management of calcium oxalate stones includes the removal of the stones with one of the previously described methods followed with measurements to prevent future stones. These include monitoring the blood calcium levels, urine pH and prescribing a diet with adjusted levels of calcium, magnesium and citrates (which bind urinary calcium). Canned food is also more preferable than dry food as it insures a higher water intake (which helps dilute the urine). Note: Be aware of pet vitamin supplements, as supplementing patients diagnosed with calcium oxalate stones with vitamin C is not recommendable. This is because Vitamin C is converted to oxalic acid which further modifies into oxalate.

cat drinking water

Struvite stones don’t always require the removal of the stones, and can sometimes be addressed with stone-dissolving diets. Acidic urine helps to dissolve struvite uroliths and also provides a less favourable environment for its formation. A diet low in magnesium levels with added acidifiers helps increase urine acidity, which can help dissolve and prevent struvite stones. However, this coincides with an increase in oxalate uroliths, low magnesium levels and urine pH both being a factor in calcium oxalate formation.

2. Urinary infections. Treatment of urinary infections varies depending on the type and severity of the infection. It may include antibiotics, fluid therapy, adjusted diet and/or urinary acidifiers.

3. Urethral obstruction. In the first step, management of urethral obstruction requires the removal of the obstruction. This can be done by draining the bladder with a catheter or gentle mechanical manipulation of the penis to dislodge the blockage. The removal or the obstruction may also be achieved by flushing sterile solution through a tube placed in urethra. After the removal of he plug, ureia is treated with intravenous fluids and if needed, antibiotics and adjusted diet may be prescribed too.

4. Feline idiopathic cystitis Because the pathology of this disease still remains uncertain, the current goals for its treatment include measurements to decrease the severity and frequency of FIC episodes. There are several medical treatments in use that result in different degrees of success.

Living with FLUTD

cute tabby orange and white cat sleeping on a window

Depending on the cause for the specific case FLUTD, after the treatment, the symptoms can disappear completely or periodically reoccur. In the cases of FIC, recurrence is a lot more common than in the other FLUTD cases. In order to reduce the incidence of recurrent symptoms, it is often advised to adequately adapt the feline diet. There are different prescription diets with adapted levels of minerals and supplement, specifically developed for management of FLUTD.

Additionally, canned food is often considered more preferable than dry food as it ensures a higher water intake. The meals should be smaller but more frequent. Environmental changes that reduce stress may provide benefit in FLUTD treatments too. This includes increasing the number of litter boxes and keeping them in quiet, safe corners, cleaning the litter boxes more frequently, maintaining a safe and stable routine and increasing one-on-one contact with a favorite hooman. Note: if your cat has been diagnosed with urinary stones, it is often recommended to recheck the cat every 3-6 months with a urinalysis and every 6-12 months for radiographs.

If recognized and addressed timely and correctly, FLUTD is considered a treatable disease in most cats. Important risk factors to keep in mind are diet, dehydration and obesity. While FLUTD is not gender specific, urethral obstruction tends to affect males more commonly than females. If you ever notice any of the previously described signs indicating problems with urinary tract, consult with a veterinarian immediately.


American Veterinary Medical Association. (2018). Feline Lower Urinary Tract Disease. Retrieved August 2018, from AVMA

International Cat Care. (2017). Feline Lower Urinary Tract Disease (FLUTD). Retrieved August 2018, from International Cat Care

Brooks, Wendy. (2004). Bladder Stones (Oxalate) in Cats. Retrieved August 2018, from Veterinary Partner

Kay, Nancy. (2018). Feline Idiopathic Cystitis (FIC). Retrieved August 2018, from Pet Health Network

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