Feline idiopathic cystitis (FIC) is a disorder of the lower urinary tract in cats causing a combination of clinical signs, such as hematuria, pollakiuria, and periuria, as well as stranguria and urethral obstruction. The etiology of FIC is unknown but there is a consensus that FIC appears to be multifactorial disease syndrome involving the urinary bladder. Known contributing factors are environmental influences and changes in the autonomic nervous system, which generate an increased stress response in affected cats, alterations in the glycosaminoglycan layer of the urinary bladder, neurogenic inflammation, and increased mast cell density in the bladder wall. Studies investigating the urine protein pattern in cats with FIC have identified differences compared to healthy cats and cats with other urinary tract disorders. It has also been shown that certain signal transduction pathways important for inflammation and apoptosis are altered.¹

There are different forms of FIC. FIC can occur without urethral obstruction (UO) (non-obstructive FIC) or with urethral obstruction (obstructive FIC). The non­obstructive form affects males and females equally. UO occurs almost exclusively in male cats and may be caused by inflammation and spasms, or by formation of matrix-crystalline plugs.

FIC is a diagnosis of exclusion, and a diagnostic work­up must be performed to rule out other specific causes. This includes a urinalysis (dipstick, urine sediment, aerobic urine culture), abdominal radiographs to identify radio-dense cystoliths or urethroliths, and ultrasound of the urinary tract to exclude focal bladder abnormalities such as polyps or neoplasms. Contrast radiographs can also be used to rule out radiolucent cystoliths, and cystoscopy can be performed to rule out other causes of lower urinary tract disease and to confirm a diagnosis of FIC.

There is no proven effective therapy for FIC. In cats with non-obstructive FIC, clinical signs resolve without therapy within 5 to 7 days. It is well known that interstitial cystitis in humans, which shares many similarities with FIC, is very painful. In cats, clinical observations have shown that analgetic treatment reduces the severity of clinical signs. A good analgetic option is Buprenorphine, which can also be given orally (0.01–0.02 mg/kg PO BID to QID). Meloxicam has not been shown to have a beneficial effect on the course of obstructive FIC², but non-steroidal anti-inflammatory drugs can still be used for their analgetic effect in well-hydrated animals with no renal impairment.

There is no prospective study investigating the effect of alpha-sympatholytic drugs; however, female cats with FIC have been shown to have an increased urethral sphincter tone.³ In addition, lowest rates of recurrent urethral obstruction of 17% to 18% in cats with obstructive FIC have been observed in studies that included alpha-sympatholytic drugs in the treatment protocol.^4,5 In one retrospective study cats treated with prazosin, a selective α1-antagoniste, had a significantly lower risk of recurrent UO than cats treated with phenoxybenzamine, a non-selective α-antagonist.⁶ However, there are no prospective clinical studies for any of these drugs.

Systemic treatments that have been investigated in randomized, placebo-controlled clinical studies in cats with non-obstructive FIC include subcutaneous PPS⁷, oral N-Acetly-D-Glucosamin⁸, and oral PPS⁹. In obstructive FIC, the effects of oral Meloxicam² and Prednisolone¹⁰ were investigated. PPS had a beneficial effect on cystoscopic lesions but it was not possible to demonstrate a significant positive clinical effect compared to the placebo for any of the treatments mentioned.

lntravesical treatments have been investigated in cats with obstructive FIC in placebo-controlled clinical trials with the aim of reducing the risk of recurrent urethral obstruction. These include: buffered Lidocaine¹¹, a combination of different glycosaminoglycans⁵, and pentosanspolysulfate⁴. None of these drugs significantly lowered the rate of recurrent UO compared to the placebo.

Optimizing the cat’s environment to reduce stress and motivating them to increase their water intake are the most important measures for reducing the risk of recurrent episodes. Many authors recommend that cats with FIC should be fed exclusively with a canned diet.¹² This recommendation derives from the results of a prospective study of cats with non-obstructive FIC.¹² In this study, only 11% of cats on the canned diet, compared to 40% of cats on the same diet in a dry formulation, experienced recurrent clinical signs. In cats with obstructive FIC, the current recommendation is to feed a moderately acidifying diet with high water content to prevent formation of struvite crystals, which are the most commonly identified crystals in urethral plugs. A more recent study of cats with non-obstructive FIC revealed a significantly lower rate of recurrent clinical episodes and a lower number of days with clinical signs by feeding a diet with an altered fatty acid profile and increased amounts of antioxidants.¹³

References

1.  Treutlein G, Dorsch R, Euler KN, Hauck SM, Amann B, Hartmann K, et al. Novel potential interacting partners of fibronectin in spontaneous animal model of interstitial cystitis. PLoS One. 2012;7(12):e51391.

2.  Dorsch R, Zellner F, Schulz B, Sauter-Louis C, Hartmann K. Evaluation of meloxicam for the treatment of obstructive feline idiopathic cystitis. J Feline Med Surg. 2016;18(11):925–933.

3.  Wu CH, Buffington CA, Fraser MO, Westropp JL. Urodynamic evaluation of female cats with idiopathic cystitis. Am J Vet Res. 2011;72(4):578–582.

4.  Delille M, Frohlich L, Muller RS, Hartmann K, Dorsch R. Efficacy of intravesical pentosan polysulfate sodium in cats with obstructive feline idiopathic cystitis. J Feline Med Surg. 2016;18(6):492–500.

5.  Bradley AM, Lappin MR. Intravesical glycosaminoglycans for obstructive feline idiopathic cystitis: a pilot study. J Feline Med Surg. 2014;16(6):504–506.

6.  Hetrick PF, Davidow EB. Initial treatment factors associated with feline urethral obstruction recurrence rate: 192 cases (2004–2010). J Am Vet Med Assoc. 2013;243(4):512–519.

7.  Wallius BM, Tidholm AE. Use of pentosan polysulphate in cats with idiopathic, non-obstructive lower urinary tract disease: a double-blind, randomised, placebo-controlled trial. J Feline Med Surg. 2009;11(6):409–412.

8.  Gunn-Moore DA, Shenoy CM. Oral glucosamine and the management of feline idiopathic cystitis. J Feline Med Surg. 2004;6(4):219–225.

9.  Chew DJ, Bartges JW, Adams LG, Kruger JM, Buffington CAT. Randomized, placebo-controlled clinical trial of pentosan polysulfate sodium for treatment of feline interstitial (idiopathic) cystitis. In: Proceedings of the American College Veterinary Internal Medicine conference; 2009.

10.  Osborne CA, Kruger JM, Lulich JP, Johnston GR, Polzin DJ, Ulrich LK, et al. Prednisolone therapy of idiopathic feline lower urinary tract disease: a double­ blind clinical study. Vet Clin North Am Small Anim Pract. 1996;26(3):563–569.

11.  Zezza L, Reusch CE, Gerber B. Intravesical application of lidocaine and sodium bicarbonate in the treatment of obstructive idiopathic lower urinary tract disease in cats. J Vet Intern Med. 2012;26(3):526–531.

12.  Markwell PJ, Buffington CA, Chew DJ, Kendall MS, Harte JG, DiBartola SP. Clinical evaluation of commercially available urinary acidification diets in the management of idiopathic cystitis in cats. J Am Vet Med Assoc. 1999;214(3):361–365.

13.  Lulich JP, Kruger JM, Macleay JM, Merrills JM, Paetau-Robinson I, Albasan H, et al. Efficacy of two commercially available, low-magnesium, urine-acidifying dry foods for the dissolution of struvite uroliths in cats. J Am Vet Med Assoc. 2013;243(8):1147–1153.