Idiopathic cystitis (Proceedings)
Feline lower urinary tract diseases are characterized by hematuria, pollakiuria, and dysuria, and are common problems encountered in feline practice. It is estimated that they affect over one half million cats in the United States annually. Although there are numerous recognized causes of these signs, the exact cause is never identified in the majority of cases. These cases are classified as feline idiopathic cystitis (FIC) and may represent up to 64-68% of non-obstructive lower urinary tract diseases. The biologic behavior of FIC is variable and may be complicated by urinary obstruction due to urethral plugs. Clinical signs in non-obstructed cats often resolve in 2-3 days without therapy, although in about 40% of cats, signs may be frequently recurrent or may persist for longer than 3 weeks. Cats with persistent signs or frequent recurrence of signs are classified as having chronic FIC.
There are numerous theories regarding the etiopathogenesis of FIC. These theories include roles for external factors (i.e. crystalluria, uropathogens such as viruses, urine toxins...), intrinsic bladder factors (i.e. autoimmunity, increased uroepithelial permeability, alteration of the mucosal glycosaminoglycan layer, mast cell infiltration, neurogenic inflammation...), or more internal/systemic problems (i.e. developmental abnormalities, abnormal neurologic or hormonal stress responses...). Unfortunately, identifying basic pathologic processes has been hindered by lack of comprehensive histopathologic descriptions of tissue samples (including urinary bladder and other organ systems) and the challenge of clearly establishing a progression or link between cystitis and con-morbid abnormalities in other systems.
Clinical features of FIC are similar to those observed in an idiopathic lower urinary tract disease of humans referred to as interstitial cystitis. Interstitial cystitis in humans is a chronic, persistent, and debilitating disorder characterized by pollakiuria, dysuria, lower abdominal pain, normal urinalysis results and distinctive cystoscopic lesions called glomerulations. Similarities between the clinical features of idiopathic cystitis in cats and interstitial cystitis in humans have prompted speculation that these two conditions are analogous to one another. These similarities also seem to extend to underlying pathophysiologic disturbances and histopathologic lesions. For this reason, several studies have been performed in cats to try to identify beneficial effects for treatments that have shown promise in human medicine.One of the primary difficulties in any clinical trial for this condition is identifying when a medication has a truly beneficial effect since the majority of cats will recover from their symptoms within 5-7 days without (or despite) therapy. Thus, it is exceptionally important to determine whether there was adequate placebo control and appropriate masking of investigators and clients when evaluating these studies.
First of all, in order to diagnose this condition, all other reasonable potential causes of lower urinary tract disease must be ruled out. This usually requires numerous diagnostic tests including a complete medical history and physical examination, minimum data base (Chemistry, CBC, UA), urine culture, imaging (radiographs, ultrasound, contrast studies, cystoscopy), and potentially others (viral testing, histopathology, etc...).
Most of the time in practice the diagnosis is presumptive based upon the cat's clinical symptoms and some of the tests listed here. This is reasonable. However, if the cat is not improving after a week, further evaluation might be indicated to look for an identifiable cause of signs.
Recent evidence has also been presented which suggests that a thorough evaluation of these patients to identify abnormalities in other systems (e.g. chronic gastrointestinal, behavioral, endocrine, or cardiovascular disorders) is warranted.