Debra M. Taylor, D.V.M.
Patti A. Tuck, D.V.M. Emily A. Lewis, D.V.M.
The term "cystitis" literally means inflammation of the urinary bladder. Although this term is rather general, there is a common form of cystitis that occurs in male and female cats. This disease is also known as Feline Urologic
Syndrome (FUS) or Feline Lower Urinary Tract Disease (FLUTD). It affects the bladder (not the kidneys), resulting in the production of bloody urine that contains microscopic crystals. The cat often urinates frequently, usually with the passage of only a few drops of urine. This is often confused with constipation.
Contributing Factors
Some of the factors which are associated with an increased incidence of FLUTD include neutering (both males and females), obesity, decreased physical activity, a diet of primarily dry food, and a decrease in water consumption.
Prevalence
The incidence of FLUTD in the general cat population is estimated at about 1%. Certainly many more cats are affected by this disorder than presented for veterinary care; some studies estimate 5-10% of all clinic admissions for cats may involve FLUTD.
Clinical Signs
Many cats will urinate in places other than the litter box, and often on hard surfaces such as tile floors, counter tops, sinks, and bathtubs. They should not be punished for doing so. In this situation, inappropriate urination is a reflection of the cat’s extreme discomfort and is not a behavior disorder.
Most cats with cystitis exhibit blood in the urine and discomfort in urinating. The discomfort is usually mild but can become much worse if it is not treated. Female cats may develop l/2 inch diameter stones in the bladder that must usually be surgically removed. Male cats may develop enough crystals in the urethra (the narrow tube carrying urine out of the body) to cause an obstruction. This obstruction prevents elimination of urine from the bladder. If the obstruction is not relieved within 48 hours, most cats will die from kidney failure and the retention of toxins that were not removed by the kidneys. Because the urethra is relatively larger in the female cat, the emergency posed by complete obstruction is almost always found in male cats.
Causes/Transmission

We are not sure of the cause of this problem. Bacterial infections are the most common cause of cystitis in dogs and humans, but almost all cats with cystitis do not have bacteria in their urine. Neutering of male cats and feeding of dry cat food have been proposed as potential causes, but these have been disproved as initiating factors. It is true, however, that many dry foods may aggravate the problem after it begins. A herpes virus has been incriminated and someday may be proven to be the cause. Despite extensive research, the cause remains elusive.
Diagnosis
Diagnosis of FLUTD is relatively straightforward based on history, clinical signs, and evaluation of a urine sample.
Therapy
Each cat with cystitis is treated according to the changes in the urine (pH, crystals, blood, etc.), the type of crystals present, the presenting clinical signs (straining, increased frequency, etc.), and the presence or absence of a bladder stone or urethral obstruction.
If neither a bladder stone or urethral obstruction is present, proper medication will generally relieve the discomfort.
A urinalysis is necessary to determine the proper medication. A special diet, explained below, will help to dissolve crystals in the urine and hasten recovery.
If the cat has an obstruction of the urethra, a catheter is passed into the bladder while he is under a short-acting anesthetic. The catheter is frequently left in place for about 24 hours. The cat is discharged from the hospital when it appears unlikely that obstruction will reoccur, usually 1-3 days later. If he is experiencing kidney failure and toxemia, intravenous fluids and additional hospitalization are needed.
Following initial treatment, you will be asked to return the cat in 7-10 days for a recheck of the urine. This is very important because some cats will appear to feel much better but the urine is still bloody or contains crystals. If medication is stopped based on how the cat appears to feel, treatment may be terminated prematurely and a relapse will probably occur.
Many cats have recurrence of cystitis. This is one reason that a virus is suspected as the cause. It is also the reason that a proper diet should be fed in the future.
Complications
The most common complication of a urethral obstruction is bladder atony. Atony means that the muscles of the bladder wall are unable to contract to push out urine. This occurs when they are stretched to an extreme degree. Not all cats with obstructions develop atony; in fact, most do not. However, if this occurs, longer hospitalization is necessary. The muscles will nearly always rebound and become functional again, but this may take several days to as long as a week.
Another complication that occasionally occurs is kidney damage. Although feline cystitis does not directly affect the kidneys, if the bladder becomes extremely enlarged, urine may backup into the kidneys and create enough pressure to temporarily or permanently damage them. If this occurs, prolonged hospitalization will be necessary to treat the kidney damage. However, with aggressive treatment, most cats will recover their normal kidney function.
It should be noted that both complications, bladder atony and kidney damage, are the direct result of the bladder becoming extremely enlarged. Both problems may be prevented by prompt recognition of the problem and prompt medical care.
A Surgical Option
Male cats that have more than one urethral obstruction can benefit from a surgical procedure called a perineal urethrostomy. The purpose of this is to remove the narrow part of the urethra that is the typical site of the obstruction. Although this prevents future obstructions, some of these cats will still have an occasional recurrence of cystitis; however they should not have another urethral obstruction.

This surgical procedure is also performed if the urethral obstruction is so severe that normal urine flow cannot be reestablished or if there are permanent strictures that develop in the urethra. Many cats with urethral obstructions have so much inflammation in their urethras that scarring may result due to the catheterization process. Of ten this is unavoidable.
Surgically changing the cat's urethra makes him more prone to bacterial infections in the bladder and bladder stones.
Therefore, this surgery is only recommended if other means of prevention or treatment are not successful. Cats that have 2 or more urethral obstructions and those that re-obstruct within a few days after a catheter is removed are good candidates for surgery. Even if bacterial infections or bladder stones occur following surgery, they are not lifethreatening like urethral obstructions so the surgery generally offers a significant benefit for the cat that really needs it.
Prognosis
The prognosis is generally good if the cat is responsive to medical management (i.e., change in diet). The prognosis is more uncertain if the cat has a long-standing obstruction or the bladder becomes atonic, as described above.
Generally, cystitis becomes somewhat less common as cats mature.
Prevention
Two things should be done to help prevent recurrence.
1) Special diets are available to help prevent this disease. The specific diet is chosen based on the type of crystals present in the urine.
The most common type of crystals present in the urine is called struvite or triple phosphate. These crystals will dissolve in acidic urine. Therefore, acidification of your cat's urine can be a significant means of prevention.
However, if your cat's crystals are not struvite, they are probably calcium oxalate. Acidification may actually make recurrence more likely if calcium oxalate crystals are present. Therefore, if at all possible, the crystals in the urine should be analyzed for their composition. This is the most important step in preventing future problems.
2) Restrict the cat's intake of dry cat food. Though dry foods do not cause cystitis, several studies have shown that the cat's total fluid intake is decreased when dry diets are fed. When the fluid intake is decreased, the urine is more concentrated with minerals and other materials that can cause future episodes of cystitis. Canned foods cause increased fluid intake and more dilute urine.
However, we know that many cats do not like canned food and that there are several distinct advantages to feeding dry food. Therefore, if there have been only a few infrequent episodes of cystitis, these other factors may be more important.
Be aware that diets sold in grocery stores are designed for preventing the type of lower urinary tract disease caused by struvite crystals. Since struvite disease is primarily a disease of young cats, older cats should not be eating them unless it is shown that struvite disease is present. In addition, older cats with kidney disease may have worsened disease if they are eating acidified diets. Therefore, store brand diets are not recommended for middle-aged and geriatric cats, as a rule. If you have older cats in the home that do not have a problem with FLUTD, they should be fed separately and offered their regular diet. For this reason, your veterinarian should be instrumental in helping you choose the food that is best for your cat.