Introduction

Diseases of the lower urinary tract of cats are summarized under the term “feline lower urinary tract disease” (FLUTD). FLUTD describes the common clinical presentation of different diseases with a wide variety of causes. The signs of FLUTD are pollakiuria, stranguria, periuria and hematuria.¹ Obstruction of the urethra occurs frequently in this disease complex.

Causes

If the cause of FLUTD cannot be identified, the disease is called idiopathic cystitis (FIC). Between 55% and 63% of the cats with FLUTD are considered to suffer from FIC.^2-5 Common causes of FLUTD are urinary calculi, urethral plugs and urinary tract infections. Further less common causes of FLUTD are neoplasia (e.g., transitional cell carcinoma), acquired or congenital anatomic defects, and central nervous system disease leading to micturition disturbances.

Diagnosis

Because all forms of FLUTD have a very similar clinical presentation, laboratory tests and diagnostic imaging are required in each case to establish a diagnosis. Recurrent episodes in the same cat can have different causes and have to be worked up completely each time.⁶ Urinalysis is very important, and urine should always be collected before any therapy is instituted. Ideally urine should be collected by cystocentesis; however, there is some debate about the danger of cystocentesis in obstructed cats. Urinalysis should include measurement of the specific gravity, a dipstick analysis, analysis of the urine sediment and a urine culture. Serum biochemical analysis can provide information about underlying diseases. Furthermore, it is important to identify and quantify metabolic disturbances, including hyperkalemia or postrenal azotemia in cats with urinary tract obstruction.

On radiographs, radiodense stones can be seen; furthermore, size and form of the bladder can be evaluated. It is important to make sure that the distal end of the urethra is on the radiograph. Ultrasound evaluation of the urinary tract provides information about the bladder wall and the content of the bladder. Diseases of the urethra can be seen by contrast urethrography.

Urethroscopy and cystoscopy are not routinely performed in cats with FLUTD.

FIC

It is still not known what’s causing FIC. Associations with viral diseases or with bacterial DNA in culture-negative urine could not be found.^7,8 FIC was suggested as model for interstitial cystitis in people.⁹ Typical glomerulations (small petechial bleedings) in the submucosa of the bladder wall are part of the human disease and are required for the diagnosis. However, cystoscopy is not routinely used for the diagnosis of FIC, and the term interstitial cystitis is only applicable for cats in the few cases where cystoscopy was performed.

Risk factors associated with FIC are male gender, being neutered, middle-aged (2–7 y), and overweight. Stress caused by husbandry or environmental factors like indoor housing are also associated with FIC.¹⁰

Cats suffering from FIC show pain, hematuria, pollakiuria, stranguria, periuria or are not able to urinate at all. This picture is not different from other causes of FLUTD.

Treatment of Urinary Tract Obstruction/Prognosis

Cats with urinary tract obstruction are emergency patients. The main goal of the therapy is to re-establish urine flow. Life-threatening metabolic derangements like hyperkalemia or severe acidosis have to be corrected immediately. Possibilities for the therapy of hyperkalemia are:

• Infusion with NaCl
• Infusion with glucose
• Regular insulin followed by a glucose bolus, followed by infusion with glucose
• Calcium gluconate or sodium bicarbonate

If urethral patency can’t be re-established, urine can be evacuated by cystocentesis. Possible side effects of decompressive cystocentesis are extravasation of urine into the peritoneal cavity and injury to a pre-damaged bladder wall. Once the urethra is patent, an indwelling catheter is left in place and connected to a closed urine-collecting system. Reobstruction ratios are reported to be between 11% and 36%.¹¹ Duration of catheterization seems to be important; leaving the catheter longer (mean 21.62 h vs. 32.1 h) was associated with a lower recurrence rate, and only establishing patency without leaving the catheter in place was associated with a higher reobstruction rate.^11,12 The size of the catheters left in place was associated with recurrence rate in one study, with bigger catheters (5 F vs. 3.5 F) having a higher reobstruction rate.¹³

References

1.  Westropp JL, Buffington CAT, Chew D. Feline lower urinary tract disease. In: Ettinger SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. St. Louis: Elsevier Saunders; 2005:1828–1850.

2.  Lekcharoensuk C, Osborne CA, Lulich JP. Epidemiologic study of risk factors for lower urinary tract diseases in cats. Journal of the American Veterinary Medical Association. 2001;218(9):1429–1435.

3.  Barsanti JA, Brown J, Marks A, Reece L, Greene CE, Finco DR. Relationship of lower urinary tract signs to seropositivity for feline immunodeficiency virus in cats. Journal of Veterinary Internal Medicine. 1996;10(1):34–38.

4.  Kruger JM, Osborne CA, Goyal SM, Wickstrom SL, Johnston GR, Fletcher TF, et al. Clinical evaluation of cats with lower urinary tract disease. Journal of the American Veterinary Medical Association. 1991;199(2):211–216.

5.  Gerber B, Boretti FS, Kley S, Laluha P, Muller C, Sieber N, et al. Evaluation of clinical signs and causes of lower urinary tract disease in European cats. Journal of Small Animal Practice. 2005;46(12):571–577.

6.  Lund HS, Eggertsdóttir AV. Recurrent episodes of feline lower urinary tract disease with different causes: possible clinical implications. Journal of Feline Medicine and Surgery. 2018 Jun 1:1098612X18783839. doi: 10.1177/1098612X18783839.

7.  Lund HS, Rimstad E, Eggertsdóttir AV. Prevalence of viral infections in Norwegian cats with and without feline lower urinary tract disease. Journal of Feline Medicine and Surgery. 2012;14(12):895–899.

8.  Lund HS, Skogtun G, Sørum H, Eggertsdóttir AV. Absence of bacterial DNA in culture negative urine from cats with and without lower urinary tract disease. Journal of Feline Medicine and Surgery. 2015;17(10):909–914.

9.  Buffington CA, Chew DJ, Woodworth BE. Feline interstitial cystitis. Journal of the American Veterinary Medical Association. 1999;215(5):682–687.

10.  Forrester DS, Towell TL. Feline idiopathic cystitis. The Veterinary Clinics of North America: Small Animal Practice. 2015;45(4):783–806.

11.  Eisenberg BW, Waldrop JE, Allen SE, Brisson JO, Aloisio KM, Horton NJ. Evaluation of risk factors associated with recurrent obstruction in cats treated medically for urethral obstruction. Journal of the American Veterinary Medical Association. 2013;243(8):1140–1146.

12.  Seitz MA, Burkitt-Creedon JM, Drobatz KJ. Evaluation for association between indwelling urethral catheter placement and risk of recurrent urethral obstruction in cats. Journal of the American Veterinary Medical Association. 2018;252:1509–1520.

13.  Hetrick PF, Davidow EB. Initial treatment factors associated with feline urethral obstruction recurrence rate: 192 cases (2004–2010). Journal of the American Veterinary Medical Association. 2013;243:512–519.