Feline lower urinary tract disease

Feline lower urinary tract disease (FLUTD) is a broad term that is used to cover a number of conditions associated with the feline lower urinary tract. It may present as any of a variety of problems such as, inflammation of the bladder (cystitis) or urethra, formation of urinary crystals/stones in the bladder (crystalluria/urolithiasis), and partial or total obstruction of the urethra. The latter condition is also known as plugged-penis syndrome and blocked cat syndrome. Complete urethral obstruction is fatal if left untreated.

FLUTD is a common disease in adult cats, affecting from 0.5% to 1% of the population. FLUTD affects cats of both sexes, but tends to be more dangerous in males because they are more susceptible to blockages due to their longer, narrower urethrae. Urinary tract disorders have a high rate of recurrence, and some cats seem to be more susceptible to urinary problems than others.

The older term, Feline urologic syndrome (FUS) was renamed to discourage the perception that the clinical signs seen represent one disease with one cause.[1]

Causes

Uroliths

Approximately 15-20% of FLUTD cases are caused by uroliths, with the most common form being calcium oxalate and struvite(magnesium ammonium phosphate) uroliths. The majority of uroliths are located in the urinary bladder, but can also form in the kidneys, ureters and urethra. Many studies have concluded magnesium in the diet as a primary cause of struvite urolithiasis in cats. However, researchers have found that urine pH is a more important contributing factor. Urine that is acidic helps to dissolve struvite uroliths and also provides a less favourable environment for its formation.

Commercial feline diets now limit the amount of magnesium and add acidifiers in the food to increase urine acidity, thereby reducing the likelihood of struvite formation. The decrease of struvite uroliths coincides with an increase in oxalate uroliths, low magnesium levels and urine pH both being a factor in calcium oxalate formation.[2][3] Oxalate uroliths are not dissolvable in cat urine and have to be removed surgically, barring those small enough to pass out the urinary tract.

Less common forms of uroliths includes ammonium urate, uric acid, calcium phosphate, and cystine uroliths.[4]

Urethral obstruction

A combination of crystal precipitates(most typically struvite uroliths) and protein matrix(mucus or blood cells) can form a urethral plug and cause a complete blockage of the urethra. Inflammation of the bladder wall can cause the protein matrix to "leak" from the wall. Even without crystal formation, a thick protein matrix may cause urethral obstruction by itself.[5] Renal failure and uremia will follow within 36-48 hours of complete urethral obstruction. The time from complete obstruction until death may be less than 72 hours.[6]

Infectious causes

Bacterial infection is a very rare cause of FLUTD, accounting for 1-5% of cats.

Others

Other conditions that can contribute to this disease include physical trauma, tumors of the urinary tract, intentional urinary retention (a common behavior seen in cats not given a suitable place to void (e.g. no litterbox or dirty litterbox)), congenital abnormalities and neurological problems. In about 60% of cases, the cause is never discovered. These are classified as idiopathic FLUTD cases or Feline Idiopathic Cystitis(FIC).

Risk factors

• Age: Uncommon in cats younger than 1 year of age. Most commonly occurs in cats within the 2 to 5 age group.
• Sex: Male and neutered male cats are at greater risk for urethral obstruction than females because their urethra is longer and narrower.[7] Nonobstructive FLUTD occur equally in males and females.
• Neutering: as above
• Dehydration:
• Diet: Dry food
• Obesity:

The disorder may be caused by a combination of these factors. For example, a diet of dry food which is high in magnesium or other minerals and high in pH, combined with inadequate intake of water may lead to favorable conditions for precipitating buildup in the lower urinary tract. However, these factors affect individual cats differently. Most cats tolerate normal dry diets with no urinary problems.

Symptoms

Regardless of cause, there is a common set of symptoms, which includes frequent trips to the litter box (pollakiuria), prolonged squatting and straining during attempts to urinate (dysuria), small amounts of urine voided in each attempt, blood in the urine (hematuria) and urinating outside of the litter box. Owners with outdoor cats may not be able to observe the symptoms associated with litter box use and should watch for unusual behavioral changes.

A cat experiencing a urethral obstruction behaves similarly to any other cat with FLUTD. However, as time passes, the bladder fills up with urine and cause painful bladder distension. Kidney failure and uremia will follow within hours. The cat becomes increasingly distressed, and may howl or cry out in pain. The male cat may constantly lick at his penis and the penis may be protruded. The cat may seek seclusion, stop eating and drinking, begin to vomit, and become lethargic and eventually comatose as toxins accumulate in the bloodstream.

Urethral obstruction is a serious medical emergency which will lead to death if not treated in time. Any cat suspected of suffering from this condition should be seen immediately by a veterinarian.

Diagnosis

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• Blood test
• clinical signs - Per symptoms
• physical examination - palpitations etc
• urinalysis - incl. use of cystocentesis
• Urine cultures for bacteria

Treatment

A blocked urethra requires immediate veterinary attention. The plug must be removed from the penis and the bladder drained. Gentle mechanical manipulation of the penis may dislodge the blockage, or a catheter might be used to drain the bladder. Intravenous fluids are given to treat uremia. Antibiotics and a special diet may be prescribed. Diets low in magnesium and urine acidifiers may be helpful. Cats susceptible to repeated attacks of this disorder may require surgery, such as the removal of the penis (Urethrostomy) to prevent its blockage.

Cats with chronic feline lower urinary tract disease caused by struvite crystals or oxalate crystals can be treated with a life-long diet of a prescription wet or dry food which minimizes the content of the building blocks of the crystals. These foods will be prescribed by vets if needed and will replace all other food to ensure a healthy urinary tract. Even after treatment, cats need to be checked regularly for urinary problems as the crystals can return.

References

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Further reading

Carlson, Delbert G. & Giffin, James M. Cat Owner's Home Veterinary Handbook. New York: Howell Book House, 1995.

External links

• FLUTD from Veterinary Partner
• Urolithiasis: Overview & Feline Urolithiasis and FLUTD at the Merck Veterinary Manual
• FLUTD Brochure by the American Association of Feline Practitioners and the Cornell Feline Health Center
• Feline lower urinary tract disease Feline Advisory Bureau
• Bladder Stones in Your Cat
• FLUTD (Felipedia.org)