• Sterile, inflammatory cystitis in cats may be caused by multiple factors, including viral or other inflammatory triggers, urothelial defects, neurohormonal aberrations, and environmental stresses.
• The disorder is characterized by occasional episodes of hematuria, pollakiuria, and inappropriate urination that are not associated with bacterial infection and are self-limiting in nature.
• Some cats have more refractory disease, with signs that recur multiple times during a given year or, less commonly, persist for longer than 7 days.
• Treatments that minimize inflammation, protect the urothelium, or modify neurohormonal or behavioral influences can be useful in decreasing the frequency of recurrence in refractory cats.
By definition, an idiopathic disorder defies clear identification of an etiology. Because of the hematuria and irritative lower urinary symptoms, multiple investigators have searched for an infectious etiology. Common bacterial organisms, however, have not been found in most young cats with this disorder. Viral particles found in some cats, and the episodic nature of the disorder, introduced the possibility of an viral etiology. However, a clear viral causation has not be demonstrated either. Without a clear infectious cause, other epidemiologic and pathophysiologic factors probably contribute to the disorder, including:
• Patient risk factors include neutering, obesity, sedentary lifestyle, living indoors, living in multi-cat households, eating predominantly dry foods
• Changes in protective layers of the urinary bladder, including increased permeability, urothelial mucosal and submucosal damage, mast cell infiltration, and defects in the glycosaminoglycan layer.
• Abnormal stress reponses and neurogenic perpetuation of inflammatory responses. Exaggerated sensory input from afferent neurons in the urinary bladder may trigger inflammatory and pain responses.
• Latent herpesvirus or calicivirus infection may play a role in individual cats.
Diagnostic evaluation for recurrent non-obstructive feline idiopathic cystitis
Many different etiologies can lead to lower urinary tract signs in cats. Although idiopathic cystitis is one of the most common causes of these signs, and can recur in an individual cat, it is important to do a thorough evaluation for other etiologies as well, especially urolithiasis in any cat, and bacterial urinary tract infections in cats with perineal urethrostomies or those undergoing recent urinary catheterization. In recurrent cases, a complete minimum data base and additional anatomical investigation are recommended.
Practical management strategies for recurrent non-obstructive feline idiopathic cystitis
Short-term relief can be used for 2 to 5 days during acute flare-ups to minimize discomfort and shorten the hematuric phase.
• Opioids. For acute flare-ups of lower urinary tract signs, short-term analgesic treatments may be useful to reduce the discomfort associated with bladder and urethral inflammation. Butorphanol (0.5 – 1.25 mg/cat PO q 4 – 6 hrs) has been recommended; longer acting buprenorphine can be considered as well. Both agents can be given as subcutaneous injections if less stressful to the cat. Opioids also have some anti-inflammatory effects that may be beneficial in this setting.
• Anti-spasmodics. Agents that relax smooth or striated muscle of the urinary tract have been advocated for symptomatic relief of pollakiuria, dysuria, and stranguria in cats with FLUTD. The anticholinergic agents propantheline and oxybutynin have been recommended for their antispasmodic effects on the urinary bladder. In one small controlled study, propantheline administration did not affect resolution of clinical signs at 5 days post-treatment when compared with placebo; however, this agent has little direct smooth muscle relaxant properties. If urinary bladder antispasmodic agents are administered, cats should be monitored for urine retention; the loss of a frequent mechanical washout of urine theoretically could delay resolution of inflammation or predispose cats to urinary tract infection.
• Alpha adrenergic antagonism. Agents acting on urethral musculature also have been recommended to facilitate urination in dysuric cats and to alleviate functional urethral obstruction in postobstructed cats. Phenoxybenzamine and prazosin are alpha-adrenergic antagonists that inhibit urethral smooth muscle contracture. These agents may be helpful in minimizing resistance in the preprostatic and prostatic portions of the urethra in cats. Diazepam or dantrolene may be more effective in relaxing skeletal muscle in the postprostatic urethra where much of the spasm occurs. Hypotension and sedation are the most common adverse effects of alpha antagonists.
• Glucocorticoid anti-inflammatory agents. Anti-inflammatory effects of glucocorticoids on leukocyte migration, vascular permeability, and arachidonic acid metabolism would be expected to suppress the inflammatory symptomatology and hematuria associated with idiopathic cystitis. However, it appears that glucocorticoids do little to alter the short-term course of typical idiopathic lower urinary tract in placebo-controlled trials. Glucocorticoid administration also is not without risk. Refractory urinary tract infection and pyelonephritis may develop, especially when glucocorticoids are administered to cats with indwelling urinary catheters.
• Non-steroidal anti-inflammatory agents. Nonsteroidal anti-inflammatory agents have also been recommended for analgesic and anti-inflammatory effects. No controlled studies are available to demonstrate a response from any of these agents.