Feline Lower Urinary Tract Disease (FLUTD) in cats

Summary

What is FLUTD in cats?

Feline lower urinary tract disease (FLUTD) describes a group of diseases affecting the bladder and urethra of cats which show similar clinical signs. Disorders that affect a cat’s lower urinary system often cause inflammation and pain in the bladder or may cause an obstruction of the urethra, which carries urine from the bladder to the outside of the body.

FLUTD is rarely diagnosed in animals younger than one year; the average age is typically four years. FLUTD can affect cats of any age and either gender. However, male cats are more prone to urethral blockages because their urethras are narrower compared to females. The most common patient with FLUTD is a young adult, neutered male indoor cat.

FLUTD is the most common lower urinary tract disorder of domestic cats, and lower urinary tract abnormalities are one of the most common health concerns of cat owners. Bladder biopsies from cats with FLUTD show increased sensory nerves in the bladder, a thickened bladder wall and inflammation. There is also thinning of the protective mucus lining which normally protects the bladder wall against damage from concentrated urine.

Expert advice from Dr Felicia:

Cats that live in a multi-cat household seem to be more prone to FLUTD, and those with an anxious predisposition. Cats with recurrent FLUTD can be difficult to manage and inappropriate urination can put a real strain on the human-animal bond.

Cost of urinary tract disorders in cats

Urinary tract disorders were the second most common health issue experienced by cats in 2024, according to PetSure claims data.

^ØBased on PetSure claims data, 2024 calendar year. Reimbursement for these claims under a pet insurance policy would be subject to limits, such as annual benefit limits or sub-limits, benefit percentage, applicable waiting periods and any applicable excess. Cover is subject to the policy terms and conditions. You should consider the relevant Product Disclosure Statement or policy wording available from the relevant provider. Please note that values calculated are based on all claims for that condition and medically related conditions in each calendar year.

Because it is difficult to predict the costs of veterinary care, it can help to have measures in place to help prepare for the unexpected. Pet insurance can help by covering a portion of the eligible vet bill if the unexpected does happen.

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Symptoms of FLUTD in cats

Unfortunately, since the urinary tract responds to inflammation or trauma in a limited number of ways, the clinical signs are rarely indicative of a particular disease or underlying cause. It is important to realise that the symptoms listed below may represent different diseases with different causes.

Expert advice from Dr Felicia:

Cats with FLUTD may have very subtle signs or may simply just not seem like themselves, but most usually have some sort of change in their urinary habits or manner, including crying or going in and out of the litter box repeatedly and trying to do a wee.

FLUTD is a collection of clinical signs that may include:

• Urination outside of the litter tray or inappropriate places
• Abnormal appearance of urine – bloody or cloudy
• Urination that appears painful or difficult, cats might cry out while urinating or be straining
• Frequent attempts to urinate
• Abnormally frequent passage of small amounts of urine
• Spending long periods of time trying to urinate
• Excessive licking of the genital area
• Lack of appetite
• Strong odour of ammonia in urine
• Lethargy
• Vomiting
• Increased water consumption
• Hard, distended abdomen

Symptoms of a partial or complete urethral obstruction by urinary stones, calculi or crystals may include:

• Any of the above symptoms
• Abdomen appears swollen
• Show pain when the abdomen is touched
• Show depression, lethargy and loss of appetite

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Causes of FLUTD in cats

While there are many conditions that can result in signs of feline lower urinary tract disease, more than half of cats exhibiting signs of FLUTD will have no identifiable cause despite extensive diagnostic testing, and when no cause is evident, it is termed “idiopathic.”

There may be more than one single cause of FLUTD. In young, generally healthy cats, some of the more commonly identified underlying causes include:

Urethral Obstruction

When a cat’s urethra becomes partly or totally blocked it becomes a potentially life-threatening condition, as the cat, usually male, is unable to urinate. These blockages are caused by urethral stones or plugs.

• Urolithiasis (urinary stones or bladder stones): These are collections of minerals that form into crystals or stones in the urinary tract of cats.
• Urethral plugs: These are an accumulation of debris from urine that forms into a soft paste-like material containing minerals, cells, and mucus-like protein. 

Urinary tract infection (cat UTI)

A UTI is an infection of the bladder and/or urethra. UTI’s can occur in cats of all ages but are more common in those ten years and older. Recurrent urinary tract infections can greatly enhance development of FLUTD. Usually urinary tract infections are caused by bacteria but fungi, parasites or even viruses can also cause infections of your cat’s urinary tract.

Feline interstitial cystitis (FIC)

Cystitis, or inflammation of the bladder, can lead to formation of a urethral plug or stones in the bladder. The most commonly identified cause of FLUTD is sterile interstitial cystitis, which has also been termed idiopathic lower urinary tract disease (IFLUTD) because no apparent cause for this serious bladder inflammation can be identified. Occasionally cystitis can have a bacterial cause (UTI). Diagnosis of FIC is made after all diseases that might cause similar signs are ruled out.

Expert advice from Dr Felicia:

Most commonly cats with FLUTD have a sterile cystitis with no obvious underlying cause, which responds to non-steroidal anti-inflammatory medication. For cats that respond poorly to this management additional diagnostics can be performed to rule out anatomic abnormalities, and then a more robust therapeutic plan including dietary and behaviour medication may be commenced.

Although the exact cause of FLUTD may remain unknown, it is a complex condition where multiple factors may contribute to the development of the disease, including:

• Urinary tract cancer or tumour
• Trauma or injury to the urinary tract
• Neurologic abnormalities
• Anatomic defects – e.g. spinal cord problems
• Kidney Disease
• Congenital abnormality
• Diabetes mellitus
• Hyperthyroidism
• Age – young to middle-aged adult
• Sex – male
• Obesity – increases risk
• Diet – water and mineral content
• Stress
• Urine pH (acidity / alkalinity) and urine concentration
• Neutering
• Inactivity
• Living in a multi-cat household
• Temperament – nervousness, fearfulness, aggression, separation anxiety
• Incontinence from a weak bladder or excessive drinking
• Abrupt changes in daily routine

How is FLUTD diagnosed?

As FLUTD is not a “disease” per se but a collection of clinical signs, it is a diagnosis of exclusion, meaning that all other possible causes of the cat’s symptoms have been ruled out.

It is important to consult the vet if your cat cannot urinate or is having trouble urinating. A male cat should always be attended to immediately because of the risk of a urethral plug forming. A female cat should be seen within 24 hours, or sooner if she is showing additional symptoms such as vomiting and lethargy.

Your veterinarian will take a full history including the onset and nature of the symptoms. Your vet will also perform a complete physical examination, including palpation of the cat’s bladder abdominally, to determine whether the cat is able to void urine. They may also perform a digital rectal palpation of the bladder and urethra to assess whether masses or stones are present.

The following diagnostic tests may be performed:

• Complete blood count (CBC) and serum chemistry profile – results are often normal.
• Urinalysis (urine test) – a urine sample is removed from the bladder with a syringe to confirm cystitis and/or reveal the presence of pus, blood, proteins, crystals or other abnormalities in the urine.
• Urine culture – a urine sample is cultured to grow any bacteria present, which can then be subjected to a sensitivity test to determine which antibiotics would be appropriate.
• Radiographs (x-rays) and/or ultrasonography of the entire urinary tract (from kidneys to urethra) – this may reveal urinary stones, lesions and urinary tract abnormalities.
• Other advanced contrast-enhanced cystography-urethrography options are available to further investigate where necessary and can be discussed with the vet.
• Analysis of a stone or urethral plug to determine its composition.

Expert advice from Dr Felicia:

Since many cats with FLUTD are painful and straining to urinate it can be hard to obtain a urine sample. Crystals can be purchased from the clinic to attempt collection of a non-sterile sample from home or occasionally if the cat’s bladder is empty on examination, the cat can stay in hospital for a few hours to allow their bladder to fill enough for a sample to be collected.

Life expectancy

Prognosis for cats with FLUTD depends on whether the diagnosis reveals an underlying and treatable cause, the effects onkidney function from the disease, duration of the disease and frequency of occurrence.

Cat urinary tract infections can usually be resolved without complications with antibiotics  and pain relief. UTIs should be managed promptly as untreated UTIs can ascend to the kidneys, heart, and other areas, resulting in more severe complications. When a sterile cystitis is diagnosed (no infection present) then anti-inflammatory pain relief, and potentially anxiolytics may be given.

Symptoms usually resolve within 7 days without treatment where no cause of FLUTD is identified. However, idiopathic cat urinary tract infection usually recurs within 12 months in approximately half of the cats that experience spontaneous remission, and multiple recurrences are possible. For cats with recurrent FLUTD it is important to have an ongoing pro-active approach to triggers by managing the cat’s environment, and other therapies such as behaviour medications to manage stress and dietary manipulation can help.

Expert advice from Dr Felicia:

For cats with recurrent FLUTD and a poor response to medical management including behavioural medication, the prognosis may be poor as the impact of inappropriate urination in an indoor cat can have a detrimental effect on the human-animal bond.

Untreated urinary problems can cause partial or complete obstruction of the urethra especially in male cats, preventing a cat from urinating. This is a medical emergency that can very quickly lead to kidney compromise or rupture of the bladder and can prove fatal without prompt treatment.

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Treatment for FLUTD in cats

Cats with FLUTD may present with mild symptoms or with extremely serious signs that qualify as a true medical emergency. The vet will assess the degree of discomfort and whether there appears to be a urethral blockage when deciding which treatment protocols to follow. The goals of treatment are to remove or rule out any obstructions of the urinary tract, relieve pain, restore urine flow, restore fluid and electrolyte balance and reduce stress.

The key to successful treatment of FLUTD lies in the vet’s ability to accurately determine any underlying cause. Where a cat urinary tract infection is the underlying cause, often little more than antibiotics are required resolve the problem. In cases of identified urethral obstructions, surgery may be required. Dietary changes may also be implemented to prevent future episodes of stone formation.

Unfortunately, more than half of cats with symptoms such as frequent urination and bloody urine will have no identifiable cause despite extensive diagnostic testing. Since optimal treatment of these diseases is specific to the underlying cause, idiopathic cases can be a challenge to treat.

Expert advice from Dr Felicia:

Cats prone to FLUTD should have an ongoing management plan to reduce flares which usually involves environment modification, a specific diet and potentially behaviour medication.

Treatment options include:

1. Antibiotics for bacterial infections – once the bacteria are identified, suitable antibiotics will be prescribed for cats with urinary tract infections.
2. Other medications – for example, anti-inflammatory pain relief drugs, anti-anxiety medication and medication that enhances the protective mucous layer of the bladder may be recommended in the short term for acute flares and potentially ongoing for repeat offenders.
3. Dietary changes – Some cases of FLUTD can be partially managed with a prescription diet:
   • A wet/canned food only diet, to reduce the concentration of urine, as diluted urine is less likely to irritate the bladder lining.
   • Cats that eat primarily wet food have a reduced incidence of blocked urethra because the concentration of minerals and crystals that form uroliths is reduced.
   • Prescription urinary diets help to increase water intake and manipulate pH of the urine, and often include supplementary ingredients to help reduce stress.
4. Increase in water intake – to dilute the urine, provide clean, fresh water at all times, e.g., by providing water fountains. Some cats prefer drinking out of different types of bowls and different areas, like the shower. Expelling of small stones through urethra (in female cats)
5. Surgery to either remove bladder stones or tumour, or to correct congenital abnormality
6. Urinary catheter or surgery to remove urethral blockage in male cats
7. Fluid therapy

Urethral obstruction 

If the urethra is obstructed, the obstruction must be cleared as quickly as possible. This is a medical emergency that can quickly become life-threatening. A general anaesthetic is required to relieve the obstruction, flush out the urethra and place a tube (urinary catheter) into the bladder to enable urine flow. To help support the kidneys and restore appropriate electrolyte balance, intravenous fluids are an important part of supportive care. A few days of hospitalisation will be required to ensure the bladder and urethra are working properly following the removal of the blockage.

If a cat repeatedly blocks, surgery to enlarge the urethral opening is usually recommended. In some cases, antibiotics and a special prescription food can be used to dissolve the stones. Medical dissolution is an option for struvite uroliths but not for calcium oxalate uroliths.

Expert advice from Dr Felicia:

The surgery that can potentially be life saving for cats with recurrent blockages is called a perineal urethrostomy. It is usually a specialist procedure and is generally considered after multiple obstructive episodes as a salvage procedure.

Management and on-going care

• Provide an adequate number of clean litter boxes (the general rule is one more than the number of cats in the household). Good hygiene of litter boxes is essential.
• Reduce stress where possible. Cats are very sensitive to changes in their environment. A move, a new person or pet in the house, boarding, and conflict with other animals can trigger a stress response. Anti-anxiety medications for more long term control may be prescribed.
• Provide good quality food and a plentiful supply of fresh, clean water.
• Obese cats are prone to developing FLUTD, so weight management is important.
• Adhere to any special dietary requirements recommended by the vet. Diets can reduce risk factors for developing uroliths (stones) but unfortunately do not prevent recurrence, which is common for calcium oxalate stones.
• Provide places for cats to rest, hide, play and explore safely, for example, window perches, climbing structures, scratching trees.

In conclusion

 FLUTD, or feline lower urinary tract disease, refers to a group of clinical signs and symptoms seen in cats that together represent a disease syndrome of the urinary tract. Symptoms of FLUTD include frequent or painful urination, bloody urine and frequent licking of the urinary opening. A key element to treating FLUTD is to determine the underlying cause, which may include bladder stones, urinary tract blockage, infection (cat UTI) or even cancer. If the cause cannot be determined, the cat is considered to have idiopathic bladder inflammation (sterile cystitis or feline interstitial cystitis).

The most common presentation is a young to middle-aged adult, spayed or neutered, overweight indoor cat with a tendency to inactivity, nervousness and/or aggression. Male cats with FLUTD are prone to developing urethral obstruction, which is an emergency situation requiring immediate veterinary care. If FLUTD is suspected, tests are required to confirm the diagnosis. This usually requires analysis of the urine; x-rays and blood tests may be required to determine if the cat is in a critical or life-threatening situation. Treatment options include medication, dietary modification and surgery to clear an obstruction. Prognosis is variable and depends on a number of factors such as the underlying cause and the duration, frequency and severity of symptoms.