Q. Please review inappropriate urination/cystitis in cats.

A. Dr. Jeanne Barsanti at the 2005 American College of Veterinary Internal Medicine Forum in Baltimore gave a lecture on feline idiopathic cystitis/urethritis. Some relevant points in this lecture are provided in this discussion.

A common presenting complaint of cat owners is inappropriate urination. Medical causes of inappropriate urination include polyuria and dysuria. In addition, incontinence could be interpreted as inappropriate urination by cat owners, too. Lower urinary tract diseases in cats are as varied as those in any other species. In young-adult cats, the most common causes of dysuria and hematuria without obstruction are idiopathic (approximately 70 percent) and urolithiasis (approximately 25 percent).

Infectious agents have been investigated without identifying a culprit. Thus, there is no definitive evidence that idiopathic cystitis is a contagious disease. There is no evidence of a relationship with FeLV or FIV. Struvite crystalluria has been proposed as a causative factor. However, struvite crystals are commonly noted in urine of normal cats. Use of acidifying diets has not prevented recurrence of clinical signs in some cats affected with cystitis.

Bladder diverticula associated with an urachal remnant have been identified in cats with lower urinary tract signs. However, urachal remnants are common in cats. One study of 735 cats used for anatomy dissections indicated that 22 percent of males and 26.5 percent of females had identifiable urachal remnants. Comparing this to the incidence of lower urinary tract signs (0.85 percent) suggests that most cats with urachal remnants do not have signs of lower urinary tract disease. Radiographic evidence of urachal remnants has been shown to resolve spontaneously with resolution of clinical signs. Appearance of urachal remnants in cats with urethral obstruction is now thought to be a consequence of bladder-wall injury, rather than a possible causative factor.

The effect of early age neutering (younger than 10-14 weeks old) on urethral characteristics and predisposition to obstruction has been evaluated. Several studies have found no effect of early age neutering on urethral diameter in male cats. No association has been found between age of neutering and occurrence of idiopathic cystitis or urethral obstruction.

Most recently, idiopathic cystitis has been compared to interstitial cystitis in women. Interstitial cystitis is a painful, progressive disease of unknown cause, characterized by dysuria. Histologically, the lesion is characterized by inflammation and edema. Because of the similarity of clinical signs, urine biochemical findings and histologic appearance, it has been theorized that idiopathic feline cystitis might be similar to interstitial cystitis. Qualitative and quantitative changes in the glycosaminoglycan (GAG) layer of the bladder have been found in affected women and cats. This is associated with an increased permeability, allowing substances in urine to pass through the urothelium to the bladder wall, where they may cause inflammation. It is not known what causes the alteration in the GAG layer. However, one important difference in the two conditions is that the frequency of recurrence of acute signs in cats declines as the cat ages.

Cats with idiopathic cystitis tend to be fed significantly more dry food than cats without this problem. Although this does not show that dry food causes idiopathic cystitis, it implies a relationship. Stress has been considered as a possible causative factor. Cats with idiopathic cystitis more likely live in multiple-cat households or with another cat with which there is conflict.

Urinalysis

It is essential that a complete urinalysis including microscopic examination of the urine sediment be performed on all cats with lower urinary tract problems. Whenever possible, urine should be collected prior to treatment. It is also important to note how the urine sample was obtained because the technique may affect interpretation of the results.

When urine is collected by cystocentesis or catheterization, a small portion (approximately 1 ml) should be placed in a sealed, sterile container. When the urinalysis suggests infection through the presence of pyuria or bacteriuria and in older cats with hematuria, this saved sample should be cultured for aerobic bacteria. If the sample was collected by catheterization, the culture should be quantitative as well as qualitative. Saved urine samples should be stored under refrigeration and cultured within six hours or placed in urine transport tubes. Hematuria is the principal finding on urinalysis in cats with idiopathic cystitis. Pyuria is minimal to mild.

Ultrasonography