Has your cat ever suffered from a disorder of the lower urinary tract? Cats occasionally develop such problems, and the signs include frequent urination, straining to urinate, bloody urine, and at times inability to urinate.

In order to recognize and properly treat lower urinary tract diseases (LUTDs), it is helpful to have a conceptual understanding of the structure and function of the urinary tract. The normal urinary tract of a cat consists of two identical kidneys. Urine formed by the kidneys passes into pliable tiny muscular tubes called ureters. The ureter from each kidney is connected to the urinary bladder. The bladder is like a balloon. Rhythmic one-directional contractions of the ureter walls transport urine formed by the kidneys into the bladder for temporary storage. Urine contained in the urinary bladder can be voided out of the cat’s body through a tube larger than the ureters. This cylindrical muscular tube is called the urethra. Urine is normally retained in the bladder primarily by resistance in the urethra caused by muscular tone. When the bladder becomes filled with urine, however, the muscular wall of the bladder contracts while the muscles in the urethral wall relax. The result is complete ejection of urine stored in the bladder.

What are the clinical signs of diseases of the bladder and urethra (or LUTDs)? They include difficult urination, bloody urine, crystals in urine, and urethral obstruction that causes complete inability to move urine from the bladder through the urethra to the outside. These signs may have different causes. Thus, there is a need for evaluation of each cat as an individual to determine the proper form of treatment and prevention. Possible causes of LUTDs include urinary stones, bacterial and viral infections, birth defects, trauma, tumors, and neuromuscular diseases. In more than 50 per cent of cats, it may not be possible to determine the underlying cause(s).

To determine the underlying cause of LUTDs, the veterinarian examines your cat, takes a medical history, and also performs urinalyses (tests on the urine) on urine samples that have not been altered by previous treatment. X-ray and ultrasound studies may be needed to locate the exact site(s) of the problem and to identify the causes of persistent or frequently recurring signs. Identifying the site and cause of urethral obstruction is especially important if some form of urethral surgery is being considered.

Although a variety of disorders can cause obstruction of the urethra (especially in male cats), no matter what the cause, complete obstruction results in dysfunction of both kidneys that, if not quickly corrected, ultimately causes death. Untreated cats usually die within 3 to 5 days after the onset of obstruction. Why is complete obstruction of the urethra life threatening? Death results from retention of wastes, especially potassium and metabolic acids, in the bloodstream. However, the retention can be reversed by eliminating the obstruction and by correcting the abnormalities in blood.

How should LUTDs be managed? Specific treatment of LUTDs should be directed at the underlying causes, only some of which are currently known. Of course, detecting known causes calls for appropriate evaluation and diagnosis. In the case of a cat with urethral obstruction, the treatment depends on the cause, site, degree, and duration of the obstruction.

To treat a bacterial infection, a veterinarian should prescribe appropriate antibiotics and eliminate or control problems in the normal body defense system. For cases of urinary stones, either medical dissolution protocols or surgical procedures may be considered.

Treatment of difficult urination and bloody urine not associated with identifiable causes remains a puzzle. Fortunately, the signs of many cats with this form of LUTD usually subside on their own. Unfortunately, the signs are unpredictably recurrent. Because specific therapy is unavailable, veterinarians often recommend therapy to treat the symptoms. When evaluating the success of various treatments, we must be careful. Many disorders in humans and animals are self-limiting, meaning that our bodies’ defense systems eliminate the diseases. Examples of self-limiting human diseases include the common cold and many gastrointestinal problems involving vomiting and diarrhea. In these cases, a treatment may seem beneficial as long as it is not harmful. A similar situation occurs in some cats with LUTDs. However, your veterinarian may recommend changes in diet, litter boxes, water availability, environment, or medications. Close communication between you and your veterinarian regarding the benefit or lack of benefit of any treatment trial will be valuable after you closely observe your cat. Remember, there is no "cure." Also remember that inability of a cat to urinate is a medical emergency that requires immediate veterinary attention.