Definition:  Feline urologic syndrome (FUS), also known as feline lower urinary tract inflammation (FLUTI) is not one disease but rather is a group of diseases of heterogeneous or multiple causes which results in clinical signs referable to the lower urinary tract including dysuria, hematuria, crystalluria, inappropriate urination, and urethral obstruction. In some cases, the clinical signs of FUS in the non-obstructed cat are due to irritation of the mucosa of the bladder and urethra by struvite crystals. If the crystals along with blood and other proteins aggregate in the urethra, obstruction may result.

The incidence of LUTD is < 1% of all cats but accounts for about 4-10% of all cases admitted to veterinary hospitals. The incidence is higher when cats are less active, as they are in cold weather since they may spend less time outdoors and urinate less frequently. Signs of LUTD usually occur between 1 to 6 years of age and occur with equal frequency in both genders. Clinical signs may wax and wane with or without treatment. If preventative measures are not taken, recurrence of clinical signs is common.

As LUTD is not one disease there is not just one cause for all cases of LUTD. Some suspected contributing factors include:

• A high ash diet may be predisposing depending on the ash constituents. Ash is what remains when a diet is burned.  If dietary ash is high in magnesium, that diet may predispose to development of LUTD with struvite (MgNH₄PO₄) crystals causing mucosal irritation. If dietary ash is high in sodium, the diet is less likely to predispose to signs of LUTD.
• A viral infection may be responsible for signs in some cats. An adenovirus causes a self limiting LUTD of children. Viruses which may play a role in cats include calicivirus (originally called Manx picornavirus), cell associated herpesvirus, and feline syncytium forming virus and most recently, bovine herpesvirus 4. There is a variable ability to isolate viruses from spontaneous cases of LUTD or to induce signs with viruses, so the role of viruses in LUTD of cats remains unknown.
• Elevated dietary magnesium and phosphorus contribute to the formation of struvite (MgNH₄PO₄) crystals which can cause mucosal irritation.
• Cats eating dry food diets may excrete less water in urine which increases urine concentration and the concentration of crystalloid material in the urine.
• Alkaline urine decreases the solubility of struvite crystals. A postprandial increase in urine pH occurs about 3-5 hours after eating.
• Most cats with LUTD have sterile urine although manipulation of the urinary tract by catheterization may lead to UTI. The role of infectious agents such as mycoplasma (ureaplasmas) that may not grow on routine culture medias is under investigation.
• Remnants of the urachus may be present at the apex of the bladder and may be present in cats with infected or bacteriologically sterile urine. Urachal remnants may also be observed in cats with increased bladder pressure in the immediate post obstruction period and may spontaneously resolve, therefore may be a consequence of obstruction, rather than a cause.
• Chronic interstitial cystitis or feline interstitial cystitis. Approximately 2/3 of cats with lower urinary tract signs do not have an identifiable cause for their signs.

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The clinical presentation of cats with LUTD is dependent upon whether or not outflow obstruction exists. Both obstructed and non obstructed cats may have a history of dysuria, pollakiuria, hematuria, inappropriate urination, and excess grooming of the genital region.  Obstructed cats rapidly become uremic and have additional systemic signs of signs of vomiting, anorexia and depression.

The physical examination of cats without obstruction is usually normal. The bladder may be so small that it is not palpable or attempts at bladder palpation may stimulate the cat to urinate. Physical examination of obstructed cats may reveal depression, dehydration, subnormal temperature, and a distended, painful bladder.

The hemogram is usually normal but may show signs of stress.

Chemistries which reflect urinary tract obstruction include increased BUN, creatinine, phosphorous and potassium. Stress induced hyperglycemia may be observed in obstructed or non-obstructed cats, the stress originating from obstruction or blood sampling.

The urinalysis is similar whether or not obstruction is present. Hematuria, gross or microscopic is commonly observed. Protein is a component of blood so proteinuria is present whenever blood is present in urine. The type of proteinuria is secretory. Pyuria may be observed reflecting an inflammatory reaction to crystals in the urinary tract. The pH is variable; if struvite crystalluria is present, urine pH is often alkaline. If the animal is azotemic, the urine pH may be acid. The urine usually has a high specific gravity.  Glucosuria is infrequently present reflecting stress hyperglycemia. If the pH is alkaline, struvite crystals may be seen.   Bacteriuria are rarely observed.

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Treatment of obstructed cats:  Obstruction is usually caused by urethral plugs comprised primarily of an organic protein matrix with smaller amounts of mineral. These plugs are loosely structured and assume the shape of the urethra. The mineral content is most often struvite (MgNH₄PO₄). Factors listed above which increase the concentration of struvite crystals in urine predispose to development of urethral obstruction. Possible sources of the protein component of urethral plugs include inflammatory cells, cellular debris from the urinary tract, blood, or prostatic secretions. Females rarely develop urethral plugs because they have a wider, more distensible urethra and no prostatic secretions.

Urinary tract obstruction is an emergency. Signs of uremia occur within 24 hours of onset of obstruction and death may occur in 48 to 72 hours. The goal is to relieve the obstruction with a minimum of trauma to the urethra. Traumatic attempts at unobstruction will cause urethral swelling and perpetuate rather than improve the condition. Unless the cat is moribund, sedation or anesthesia will be needed to unobstruct the urethra. Anesthesia can be induced using short acting injectable agents. Low dose IV ketamine can be used but avoid high dose IM administration. Inhalation anesthetics may be used.

Prior to inducing anesthesia, an IV catheter should be placed for fluid therapy and correction of hyperkalemia.  An ECG should be performed to assess if hyperkalemia is causing a cardiac arrthymmia.   Treatment should be initiated for cardiac arrthymmia prior to induction of anesthesia. Fluid therapy should be initiated with potassium free fluids (0.9% NaCl) to correct dehydration and hypovolemia.

Subsequent to induction of anesthesia, and before passing a urinary catheter, an attempt should be made to dislodge the plug by massaging the penis (rolling it between the fingers) and gently compressing the bladder. Occasionally a plug can be dislodged in this way.

Most often it is necessary to pass a urinary catheter to relieve the obstruction.  Avoid additional urethral trauma by using gentle technique and a well lubricated catheter. As the catheter is inserted, a sterile fluid such as saline is infused in an attempt to dilate the urethra and generate hydrostatic pressure to break up the obstructing plug.

You can use one of several catheter types:

• polyethylene open ended
• polyethylene closed ended with side holes
• sovereign rubber catheter
• Minnesota Olive tipped catheter

Minnesota Olive tipped catheters are a set of rigid catheters of different sizes (length and diameter) which have an olive-shaped blunt insertion end. Progressively longer catheters are inserted until the obstruction is relieved.

Sovereign rubber feeding tubes are flexible and therefore difficult to pass while the cat is obstructed but because they are flexible, they are less traumatic to the urethra. They may be placed after the obstruction is relieved with a more rigid catheter if the intent is to leave a catheter in place. Open ended polyethylene and side hole polyethylene catheters are pictured. Which to use is a personal preference. In my experience, the open ended catheters are more effective in relieving obstruction. The suture tab must be placed around the catheter before it is inserted into the urethra. All 3 catheters are size, 3 1/2 French. (French/3 = outer diameter in mm)

appearance of the insertion end of the catheters 

    The cat is positioned in either lateral or dorsal recumbency. To reduce urethral trauma, the penis should be extruded from the prepuce and held parallel to the vertebral column. The cat's head is to your right.

Passing a urinary catheter in a male cat requires two people. One person exteriorizes the penis and the second person passes the catheter. A finger tab cut from the sterile package that the catheter was wrapped in, can be used to manipulate the catheter without touching it. (If this is not clear, see urinary catheterization of the dog from the selection menu) The catheter should be lubricated with aqueous lubricant. The penis and prepuce should be cleansed with antiseptic solution. In this picture, the person passing the catheter has a small (3 to 6 ml) syringe filled with saline that is slowly being infused to dilate the urethra ahead of the catheter and break up the obstructing material. The flushing solution can be lactated ringers solution or sterile saline mixed with aqueous gel. Lidocaine should be used with caution in cats as systemic absorption through the inflamed urethral and bladder mucosa can be toxic.

Avoid using traumatic probes made of rigid materials which may tear the urethra.

Once the catheter is in the bladder flush small volumes of   sterile solution in and out of the bladder to dilute crystalloid debris. Avoid excessive infusion pressure which could result in bladder rupture or reflux of urine into the renal pelves.

To obtain a urine sample for urinalysis and culture which is not contaminated by infused fluid, collect a sample by cystocentesis before flushing the bladder.

If a catheter cannot be passed, cystocentesis can be performed to temporarily decompress bladder.

A large syringe attached to a needle, extension set and 3 way stopcock should be used to empty as much urine as possible from the bladder without having to repeatedly  puncture the bladder.

The needle should be inserted at an angle close to the neck of the bladder so the bladder does not fall away from the needle as it gets smaller as urine is removed.

To leave the urinary catheter in place or not:

The urinary catheter should be removed if the cat was easy to unobstruct and if bladder expression yields a wide urine stream (~ the diameter of an 18 gauge needle).  If the urine stream is narrow ("piss poor stream"), it was difficult to relieve the obstruction or the cat is unstable and may not tolerate a second anesthesia, the urinary catheter should be sutured in place and left for 24-72 hours. An Elizabethan collar is needed to prevent catheter removal by cat. Indwelling catheters often result in UTI. Attempt to attach the catheter to a sterile closed urine collection system. Unfortunately cats have a tendency to circle and tie knots in the collection tubing in which case the catheter may need to be left open.

The bladder should be palpated several times daily and if it doesn't appear to be emptying, manual expression should be performed.

Peritoneal dialysis can be used to stabilize a patient that cannot be unobstructed.

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After relieving an obstruction, the elimination of wastes that were retained will result in osmotic diuresis. Fluid administration is indicated to prevent dehydration and to promote increased urine volume to flush and dilute remaining crystalline debris. 

Potential sequel of obstruction include:

• urinary tract infection. If a catheter is left in place a urine culture should be obtained at the time of catheter removal.
• urethral tear
• bladder atony from overdistension. Atony is diagnosed by the presence of an enlarged bladder that can be easily expressed, resulting in a normal size urine stream. Treatment for atony is to keep the bladder small by manual expression and the use of a cholinergic agent, bethanechol. If manual expression is difficult drugs can be used to relax the urethral sphincter.

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Medical treatment of the non-obstructed cat:   Non obstructed cats often have intermittent signs which often resolve within 7 days, with or without treatment, but then  recur in weeks to months. A urinalysis should be performed to determine if struvite crystals are present.

How can you collect urine from a cat that is pollakiuric? These cats may have such a painful bladder that they will void as soon as you palpate the bladder.

• cover the litter pan loosely with plastic. The cat will often urinate on top of the plastic
• use non absorbent beads (e.g. Styrofoam) in the litter pan instead of litter

Treatments that have been recommended (but not all of them logical or safe) include:

• Antibiotics are only rational if a urinary tract infection is confirmed. Antibiotic/placebo trials have shown no difference in the duration of clinical signs of dysuria/hematuria.
• If struvite crystals are observed, measures should be taken to increase the solubility of these crystals. Augmentation of urine volume reduces the concentration of struvite crystals. The food can be salted to encourage water consumption or a high salt diet such as SD feline (Hills) can be fed.

  Dietary reduction of phosphorus and magnesium will reduce crystal formation. Hills SD feline contains 10 mg magnesium per 100 Kcal of diet. It is currently recommended to feed feline SD for 2 to 3 months after an episode of clinical signs, then change to a diet that contains less than 20 mg of magnesium per 100 kcal of metabolizable energy (e.g. Hills CD, 16 mg Mg per 100 Kcal of diet). For a list of other diets that are low in magnesium see Small Animal Nutrition III by Lon Lewis et al, Mark Morris Associates, 1987, Table 5, p 9-10.

Urine acidifiers may be helpful as crystals of struvite have a greater tendency to form when urine pH is >6.8. Urine becomes more alkaline 3-5 hours after a meal so acidifiers should be given with all food to reduce post prandial alkalinity. Urine pH should be maintained between 5.9 & 6.4. A pH < 5.9 can disrupt calcium homeostasis. SD and CD diets result in acid urine and additional acidification is not indicated. If a non acidifying diet is being fed, acidifiers that are effective in the cat include ammonium chloride, and dl-methionine (avoid enteric coated tablets, they may be passed intact in the stool). The degree of acidification is dependent upon the acidifier being consumed in relationship to the amount of diet consumed, therefore, urine pH should be monitored to assure adequate acidification.

"All things considered" (expense, ease, monitoring, reduction in pH and magnesium as well as augmented urine volume), prescription diets (SD, CD), may be preferred over a combination of acidifiers, salt and magnesium restricted diet. Grocery store brands of cat food are now available that meet the objectives of acidification, low magnesium and dilution of crystals. If the lower urinary tract signs persist for > 10-14 days after initiating dietary changes, either the cat is eating something other than the prescribed diet or the lower urinary tract signs are due to something other than struvite crystalluria.

• Analgesics like phenazopyridine (Azo Gantrisin) should be avoided in cats because Heinz bodies and methemoglobinemia may result.
• Muscle relaxants like propantheline have no effect on duration of signs and can cause urine retention.
• Anti-inflammatory drugs such as DMSO may reduce signs in some cats although report are anecdotal and there have been no controlled clinical trials to evaluate effects of DMSO.
• Glucocorticoids demonstrated no benefit in a recent study.
• Other treatments with no convincing rationale application as of yet include testosterone, megestrol acetate, castor oil, vitamin A, and crystal inhibiting agents (Cure cal).

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Recurrent LUTD should initiate a search for an underlying cause. This may in turn dictate specific therapy. Some cats with lower urinary tract signs may have one of the following disorders:

• uroliths (true calculi instead of aggregates of amorphous crystals)
• bacterial urinary tract infection
• neoplasia (for example transitional cell carcinoma of the bladder or urethra)
• incomplete emptying due to neurogenic disease
• interstitial cystitis

Interstitial cystitis: The signs of LUTD in cats are similar to interstitial cystitis in women which is a disease characterized by painful frequent urination without any identifiable cause.  There is a long list of signs which must be present to diagnose an individual with interstitial cystitis but the most important include consistent clinical signs and the identification of glomerulations which are submucosal petechial hemorrhages observed on cystoscopic examination. Although the cause of interstitial cystitis is not known, a consistent finding is a defect in the urothelial glycosaminoglycan layer (GAG) which may allow urine to penetrate into the bladder wall causing inflammation. Similar signs and cystoscopic abnormalities have been observed in cats suggesting that a disease like interstitial cystitis occurs in cats. The clinical signs wax and wane in both humans and cats and appear to be precipitated by stress. Stressful events for cats which may precipitate signs include moving to a new home, weather changes and holidays in which the household routine is disrupted.

70 of the 109 cats in this study reported in the AVMA journal had radiographic or cystoscopic evidence of bladder inflammation. Only 25% of these cats had crystalluria. This case series showed a significant association between idiopathic cystitis and the feeding of a dry diet.

Treatments which may improve clinical signs include:

• amitriptyline 2.5 to 12.mg orally once at bedtime
• antihistamines
• glycosaminoglycans

The long term safety of amitriptyline use in cats has not been evaluated.

Environmental treatment with pheromones

Pheromones affect the limbic system and hypothalamus to alter the emotional status of the animal. Five facial pheromones have been isolated from cats. Feliway is a synthetic analogue of a feline facial pheromone which may decrease anxiety related behavior of cats. The product is sold as a spray and a room diffuser. The diffuser can be placed in room in which the cat inappropriately urinates. The effect lasts about 30 days. Some of the reported positive effects include decreased spraying in multi-cat households, decreased marking, and a decrease in scratching behavior.

Environmental Enrichment

Stress is considered a factor in the development of signs of LUTD labeled as interstitial cystitis.

The web site: The indoor cat initiative provides ideas (in lay terms) for ways to reduce stress in the life of a cat. Topics include:

• food preferences that may mimic "prey"
• water preferences
• litter preferences, location, number of boxes
• space (hiding, climbing, scratching)
• play
• inter-cat conflict

This information is also published: Feline idiopathic cystitis: current understanding of pathophysiology and management 

There are few indications for surgical treatment of cats with LUTD.  Calculi may be removed surgically or dissolved medically. Perineal urethrostomy is the amputation of the penile urethra, removing the narrowest part of the urethra where urethral plugs often lodge. Perineal urethrostomy will usually prevent reobstruction but not the other signs of LUTD. Perineal urethrostomy may increase the chance of developing a urinary tract infection. In one group of 35 cats that had perineal urethrostomies, 23% had positive urine cultures 2 years after surgery although all were asymptomatic. Bacteriuric cats are at risk for development of pyelonephritis.

Surgical removal of a urethral diverticulum is of questionable value if the cat is abacteriuric, but may benefit cats with UTI.