Ultrasonography is a useful tool for evaluating the urinary bladder of cats with dysuria/hematuria as long as the bladder contains urine. It is difficult to image the empty bladder, a problem in markedly dysuric cats without obstruction. The urethra, because of its passage through the pelvis, is not able to be imaged by transabdominal ultrasonography. The advantage of ultrasound over survey abdominal radiography is that both radiolucent and radiodense calculi, of relatively small size (including "sand ____ same thing as observed echogenic particles") can be detected. In fact, ultrasound is so sensitive that occasionally calculi diagnosed by ultrasound cannot be found at surgery. Bladder-wall thickening is the primary finding in idiopathic cystitis.

Management of cystitis

Most cats improve, regardless of therapy, within five days. If the signs do not abate within seven days, a diagnostic plan to rule out other causes of hematuria and dysuria should be instituted. Antibiotic therapy is not indicated in cats with idiopathic cystitis as it has been shown to be no more effective than placebo. Subcutaneous fluids (100 ml lactated Ringers), a smooth muscle relaxant (propantheline bromide, 7.5 mg PO) and anti-inflammatory doses of prednisolone (1 mg/kg/day PO) as compared to no therapy have indicated no difference in response. Amitriptyline at 5 mg per cat daily PO is also no more effective than a placebo in resolving hematuria, although pollakiuria responded more quickly. Recurrence rate within six months is higher in the cats that are treated with amitriptyline. Amitriptyline at 10 mg per cat for seven days is no more effective than a placebo and has a high incidence of adverse effects. Drugs to relieve pain may be useful. Reported adverse effects in cats include sedation, urinary tract infection, neutropenia, basophilia, hyperbilirubinemia and increased serum ALT.

If survey radiography and ultrasonography are normal, or only show a thickened bladder wall, but the cat continues to have dysuria and hematuria beyond five to seven days, symptomatic therapy is recommended, although proof of efficacy is lacking. Change of diet to one that increases water intake (canned food) is often the approach recommended.

Management of urethral obstruction

The cornerstones of therapy remain relief of obstruction and parenteral fluid support. Alkalinizing balanced electrolyte solutions (such as lactated Ringers) are appropriate for most cats. Management varies with the severity of clinical signs.

After the obstruction is relieved, a sterile, flexible 3.5F rubber feeding tube type catheter should be inserted into the bladder, collecting a urine sample for urinalysis if one has not already been obtained by cystocentesis. Flexible catheters are preferred because of their longer length. Ten cm polypropylene catheters often do not reach the bladder lumen. Flexible rubber catheters also produce less bladder and urethral trauma. The catheter should be inserted just to the bladder by determining the point at which urine is first obtained by aspiration. If a large quantity of crystalline material or blood is evident in the urine, the bladder is repeatedly flushed with 10-20 ml aliquots of a sterile isotonic solution until the returning flushing solution is relatively clear.

Whether the catheter is removed or sutured in place should be based on the characteristics of each individual case. Leaving the catheter in place prevents immediate re-obstruction and facilitates monitoring of urine output, but also leads to bacterial urinary tract infection and urethral irritation. If the urethral catheter is left in place, a closed drainage system should be established. An Elizabethan collar is usually necessary to prevent the cat from removing the urethral catheter or disconnecting the drainage system.

At present, the best recommendation is to leave the catheter in place only if one of the following conditions is present:

• the obstruction was relieved with difficulty;
• the urine stream is weak and small after relief of obstruction or a large amount of crystalline debris is evident with bladder flushing;
• the cat is uremic;
• detrusor dysfunction is present secondary to over distention.

To avoid catheter-induced complications, the catheter should be left in place as short a time as possible.