Feline Lower Urinary Tract Disease

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The feline lower urinary tract disease (FLUTD, "lower uropathy of cats," feline lower urinary tract inflammation , FLUTI; outdated: Feline urologic syndrome , FUS) is an in house cats occurring disease complex lower urinary tract ( bladder and urethra ). In terms of cause and development, these are actually different diseases that correspond to the Lower Urinary Tract Symptoms in humans.

Between 4 and 10% of all cats presented to a veterinarian are patients with urinary tract disease. There is no gender dependency. The majority of cases occur in winter and spring. The probability of a recurrence in an animal that has become ill is given as 30 to 70%. Obesity is considered a predisposing factor. The mortality rate is given as 6 to 36%.

FLUTD etiology

The ideas about the etiology of the FLUTD have been subject to numerous currents since the 1960s. Initially, bacteria and viruses (especially caliciviruses ), i.e. an infectious nature, were seen as the cause. Today we know that urinary tract diseases are infectious in only a small proportion of cats, and practically never in young cats.

A hypothesis that became fashionable in the 1970s focused on struvite stones as the main trigger of the FLUTD. An excessive intake of magnesium through food and an excessively high pH value were assumed to be the most important disease-causing factors. The feed industry reacted to these research results and changed the recipes from the mid-1980s to low-magnesium and uric acidic ingredients. The result was that the number of struvite stones decreased rapidly and calcium oxalate stones took their place .

A fourth hypothesis postulated malformations in the urogenital tract, in particular vesicourachal fistulas (remnants of the fetal urinary tract, the urachus ) as a decisive factor. Today it is assumed that the majority of these urachian fistulas are more of a consequence than a trigger of a FLUTD.

The most recent hypothesis was that of interstitial cystitis (cystitis affecting the interstitium ), comparable to human interstitial cystitis , a benign inflammation of unknown origin.

The main problem with the etiology is that the term FLUTD was used as a collective term for very different clinical pictures. Osborne et al. (2000) therefore recommend using the term only for diseases of unknown origin (“ idiopathic ”), but avoiding this term for definable infectious diseases or urinary stones . However, this perspective has not caught on internationally, so that today essentially three clinical pictures are subsumed under the term:

  1. Feline Idiopathic Cystitis (FIC)
  2. infectious cystitis
  3. Bladder stones

Feline Idiopathic Cystitis

Feline Idiopathic Cystitis (FIC) is responsible for about half of FLUTD cases in young and medium-aged cats. The cause is unknown ( idiopathy ), but stress seems to be an important factor in the development of the disease. The FIC usually heals on its own after a few days, and pain medication can be administered to help. To prevent relapse, any stressors should be identified and, if possible, eliminated.

Bladder stones

The formation of bladder stones ( urolithiasis ) is determined by chemical and physical factors in the urine. If certain compounds become relatively oversaturated, they can crystallize out and form larger concretions. The chemical composition of the stones or smaller particles (bubble grit) in cats is mainly determined by two factors: food and drinking water intake. Depending on the recipe of the feed manufacturer, there have been repeated shifts in the composition of the stones in cats in recent decades. Currently struvite (magnesium ammonium phosphate hexahydrate) and calcium oxalates ( whewellite and weddellite ) are dominant. Urate stones rarely occur, for example in the presence of a portosystemic shunt .

In contrast to dogs, 95% of the struvite stones in cats are formed in sterile urine. The removal from the bladder can be done by hydropropulsion with concrements smaller than 3 mm (female cat) or 1 mm (male). The laser lithotripsy is only available in a few veterinary hospitals so that larger stones are usually surgically removed. The stones can be dissolved by acidifying the urine, for example by adding methionine to the feed. However, methionine can cause haemolytic anemia in cats . In addition, the magnesium intake through food should be reduced. With special food adapted to these requirements, the stones can be dissolved within 18 days.

Calcium oxalate stones are observed in some breeds of cats ( Ragdoll , British Shorthair , Oriental Shorthair , Havana , Scottish Fold , Persian , Exotic Shorthair ) and can also appear in the upper parts of the urinary tract. Increased excretion of calcium and oxalates as well as concentrated urine are also considered to be triggers, as is reduced magnesium or phosphate excretion. Calcium oxalate stones cannot be dissolved in a diet, but increasing the amount of water you drink is an important complementary therapy. This can be done by increasing the attractiveness of the potions or by giving hydrochlorothiazide .

Obstructive urolithiasis , i.e. the obstruction of the urinary tract by stones, is particularly critical in cats . This is an emergency and requires immediate veterinary intervention.

Infectious cystitis

Cystitis caused by bacteria is rare in cats younger than 10 years. Only about 2% of the FLUTD cases in this age group are infectious, in older animals the proportion increases to 45%. In most cases, infections are caused by a single pathogen (monoinfection), with Staphylococcus felis and Escherichia coli being the most common triggers. Yeasts ( Candida albicans , Cryptococcus ) and fungi ( watering can mold , Blastomyces ), which cause less than 1% of all urinary tract infections, are much rarer . Urinary hairworms ( Capillaria plica and Capillaria feliscati ) can also cause cystitis.

The diagnosis is made on the basis of a urine culture with sterile urine. The safest way to treat bacterial bladder infections is through an antibiotic chosen on the basis of an antibiogram . If no antibiogram are available from the International Society for Companion Animal Infectious Diseases (ISCAID) amoxicillin or trimethoprim - sulfonamide recommended combinations, in Gram-negative bacteria, a fluoroquinolone . A treatment duration of five to seven days is usually sufficient; ideally, the end of treatment is ensured by a negative urine culture.

Complicated bacterial urinary tract infections may require treatment for four to six weeks. Complicated courses are present if there are more than two infections per year and if there are anatomical or functional changes in the urinary tract. After about a week, the urine culture should be repeated in order to check the effectiveness of the selected antibiotic.

Fungal infections are treated with fluconazole or amphotericin B for four to six weeks.

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  1. ^ RW Nelson, CG Couto: Small animal internal medicine. 3. Edition. Mosby, 2003, ISBN 0-323-01724-X .
  2. ↑ CA Osborne et al .: Medical management of vesicourechal diverticula in 15 cats with Lower Urinary Tract Disease. In: J. Small Anim. Practice. 30/1989, p. 608.
  3. ^ CA Osborne et al.: Feline Lower Urinary Tract Diseases. In: SJ Ettinger, EC Feldman (Ed.): Textbook of Veterinary Internal Medicine. Volume 2, Chapter 175, pp. 1710-1747.
  4. ↑ Sarah Caney et al: Idiopathic cystitis of the cat. In: Vet. Focus. Special edition "Treatment of Urinary Tract Diseases", May 2014, pp. 18-25.
  5. ↑ a b c Sarah Caney et al.: Treatment of urolithiasis in dogs and cats. In: Vet. Focus. Special edition “Treatment of Urinary Tract Diseases”, May 2014, pp. 36–45.
  6. ↑ a b c d Sarah Caney among others: Diagnosis and treatment of urinary tract infections: An update. In: Vet. Focus. Special edition “Treatment of Urinary Tract Diseases”, May 2014, pp. 26–35.