Cat resting on the bed.

Feline Lower Urinary Tract Disease (FLUTD)

Feline lower urinary tract disease [known in the past as feline urologic syndrome (FUS)] is a disease syndrome of cats characterized by the formation of crystals (the most common are struvite and calcium oxalate crystals) within the urinary bladder.

These crystals, in turn, cause inflammation, urinary bleeding and straining, and sometimes life-threatening obstruction to the normal flow of urine out of the bladder. No one knows for sure why some cats get FLUTD and others don’t.

Many potential causes have been hypothesized, including viruses, abnormal urinary retention, obesity, bladder defects, and—the most popular theory to date—improper diet. In reality, one or all of these factors might play a role in the occurrence of FLUTD.

If a cat is prone to this disorder, it will usually show some signs of the disease by the time that it is 3 years of age. Both male and female cats are at risk of developing FLUTD; however, males have a greater likelihood of developing a life-threatening obstruction simply because the male urethra is smaller than that of the female and can become plugged with crystals more easily.

If such an obstruction occurs, urine can flow back into the kidneys, causing damage to these organs and also causing toxins to begin building up in the bloodstream. Early clinical signs of FLUTD result from the irritation that these crystals cause within the bladder itself.

These can include inappropriate urination in places other than the litterbox or normal elimination areas, increased licking at the genital region, straining, frequent attempts at urination with crying or vocalization, and blood in the urine.

Cats often lose their appetites and become more irritable as well. More seriously, male cats suffering from partial or complete obstruction of the urethra can exhibit vomiting, intense lethargy, and a distended, painful abdomen.

Diagnosis of FLUTD is based on clinical signs, physical examination, and a urinalysis. An enlarged, painful bladder can also be palpated in those cats suffering from some degree of obstruction.

If a bladder infection is suspected, then urine cultures might also be performed. The obstructed cat will usually have high levels of kidney enzymes (BUN, creatinine) present in its bloodstream, signifying the toxin buildup and kidney destruction that is occurring.

Most veterinary hospitals are equipped to monitor these enzymes. If an actual obstruction is suspected, then rapid treatment is essential to save the life of the cat. Obstructed cats are immediately placed on intravenous fluids to help dilute the toxin levels within the bloodstream.

A catheter is then inserted into the urethra to “unplug” it in order to reestablish urine flow. Once this flow is reestablished, the bladder is flushed repeatedly with sterile saline to remove any crystals that might be remaining within.

The veterinarian must decide whether to keep the urinary catheter in place for a few days. While catheterized, these cats are placed on antibiotics to prevent the occurrence of any secondary bladder infections as a result of the catheter. Intravenous fluids are continued in the hospital setting for 2 to 3 days after the obstruction is relieved.

For the cats that are not obstructed but still are showing signs of FLUTD, smooth-muscle relaxants and anti-inflammatory medications can be used to help reduce the discomfort and urge associated with this disease.

The use of antibiotics in such patients is still controversial; studies have shown that bacterial infections are present in less than 20 percent of the cases.

However, if urine culture confirms the presence of such, antibiotics are, of course, indicated. If struvite crystals have been diagnosed, altering the pH of the urine in order to dissolve any crystals present within the bladder is another important step in treating this disease in both obstructed and unobstructed felines.

Rendering the urine more acidic will help dissolve existing struvite crystals and help prevent the formation of new ones.

Most veterinary researchers agree that diet plays the foremost role in the creation and in the treatment and prevention of this disease syndrome. Dry diets with high contents of magnesium and ash (mineral) levels are the biggest culprits in promoting FLUTD in cats.

Unfortunately, many of the commercial supermarket brands of cat food contain these excesses. Diets specially formulated for the prevention of FLUTD can be obtained in both moist and dry forms from most veterinary offices and some pet supply stores.

Because of its high calcium and mineral content, cow’s milk should never be offered to those individuals prone to FLUTD. Besides feeding a diet that promotes a healthy urine pH and is low in magnesium and ash, providing cats free access to a fresh water supply is a must.

Increased water consumption will help increase the number of urinations each day, effectively keeping the bladder flushed out. In fact, most commercial diets formulated for the prevention of FLUTD have an increased salt content to promote increased water consumption.

With these increased urinations comes the responsibility of keeping the litterbox cleaned on a regular basis. Many cats refuse to urinate in a dirty litterbox, a practice that encourages urine retention and FLUTD.

Although it might not seem important, regulating the frequency of meals fed can play a direct role in the prevention of FLUTD. After a cat consumes a meal, its urine undergoes a temporary rise in pH.

For those cats allowed to eat and nibble all day long (such as those fed dry foods), this might promote relatively constant alkaline urine, and thereby predispose to struvite crystal formation. As a result, in terms of preventing FLUTD, offering one or two meals a day rather than free-choice meals is preferred.

Obese cats are more prone to FLUTD than their slimmer counterparts, so weight control is an important preventive measure to follow as well.

Overweight felines, especially those who have exhibited signs of FLUTD in the past, should be placed on a reducing diet prescribed by their veterinarians and have their activity levels increased until the desired weight is reached.

Once weight loss is accomplished, they can be switched back over to preventive-type rations. Without proper dietary management, FLUTD can be expected to recur over 50 percent of the time. In some cats, however, FLUTD recurs over and over again, even with dietary management.

In these instances, treating the symptoms when they first appear and continuing with preventive measures will usually prevent such episodes from turning serious.

For those male cats that have had recurring obstruction, a special operation known as a perineal urethrostomy might be indicated to reduce the danger of death due to urinary blockage.

This surgery involves the removal of the end of the penis and widening the urethral opening, effectively allowing for free passage out of any and all crystals.

Keep in mind that such a procedure is not intended to cure the FLUTD; it merely lessens the risk of severe, life-threatening complications associated with it.