DISEASES OF THE LOWER URINARY TRACT
In this text, the Lower Urinary Tract is defined as every part of the urinary system except the kidneys. While the kidneys filter blood and produce urine, the remainder of the system is concerned with storage and elimination of this waste liquid. This includes the ureters, which carry urine from the kidneys to the bladder, the urinary bladder which stores urine, and the urethra, which is the tube that carries urine out of the body.
By definition cystitis is inflammation of the urinary bladder. Many cat owners erroneously confuse this with being a "bladder infection". While bacterial infections of the bladder do occur, yeasts and mycoplasma organisms have also been implicated. Furthermore, there may be other factors which influence the formation of bladder disease including drug therapy, diabetes, which causes excess sugar to be in the urine, reproductive tract infections, bladder stones, the formation of crystals in the urine which can irritate the bladder wall, feline urologic syndrome and traumatic damage to the bladder can all lead to cystitis.
Infections of the bladder most commonly ascend there, meaning literally, they crawl up from outside. Thusly, female cats more commonly experience this condition as the infection has a shorter distance to travel. Infections can also make their way to the bladder through the blood, from the kidneys, through the lymphatic system and by extension from other nearby infections.
Clinical signs include having to void frequently, straining to urinate, pain when urinating, blood in the urine, foul or unusual odor of the urine and sometimes an increased thirst. Diagnosis is based on these symptoms, physical examination, urinalysis, urine culture, blood counts, organ function tests, X-rays and sometimes biopsies. Most acute or one-time cases can be easily diagnosed while recurrent and chronic cases of cystitis require a more involved diagnostic work-up.
TREATMENT OF CYSTITIS
Unrelated or predisposing causes of cystitis always need to be addressed. Antibiotics, often for 3-6 weeks may be needed, anti-inflammatory medications to reduce swelling and bleeding are often used, special diets, and giving canned foods or broth to help flush the bladder are usually employed. All cases of recurrent cystitis should have a more complete diagnostic work-up performed if treatment and control is to be successful.
UROLITHIASIS (BLADDER STONES)
This condition refers to "stones" forming in the urinary tract. The location of such stones is most commonly the urinary bladder, but stones can also form in the kidneys, ureters and urethra. In the right location they can prevent urination and lead to acute renal failure which would be considered a true urologic emergency. Most stones, however, cause irritation and damage inside the urinary tract.
The size, quantity and types of stones vary greatly with no specific formula for their development existing. Common stone types include struvite, calcium oxalate, urate, silica, cystine and calcium phosphate. Formation is caused by complex combinations of kidney function (metabolism), minerals in the diet, urinary tract pH, infections and abnormal metabolites being present in the urine. The composition of the stone(s) is most important with regards to treatment rather than to the symptoms produced. Many cats produce small struvite crystals rather than large stones. These can produce a sterile form of cystitis.
Clinical signs of urolithiasis are often similar to that of cystitis and include blood in the urine, straining to urinate, frequent urination, increased thirst, urinating in unusual places or where inappropriate, urinating small volumes of urine, unusual urine odor and sometimes abdominal distention or pain. Some cats have been known to exhibit no symptoms at all! Diagnosis is based on history, physical examination, X-rays including X-rays taken with dye being placed into the bladder, urinalysis, and urine culture. Sometimes kidney function tests will also be needed.
TREATMENT OF UROLITHIASIS
Some difference of opinion exists between veterinarians as how to best treat stones in the urinary tract. Surgical removal is effective, especially if the stones are in the bladder and the patient is not a high surgical risk. Certain drugs and diets can be used to dissolve stones or crystals, but certain stones cannot be dissolved and to dissolve those that can be dissolved assumes that one knows the chemical composition of the stones without doing any analysis. Also, while waiting to see if the stones dissolve, the cat still suffers the consequences. Therefore, this author greatly favors quickly removing and identifying the stones, then using special diets and/or medications to prevent further recurrence.
If a male cat has become obstructed with a urethral urolith, immediate attention is required. Back-flushing of the urethra to dislodge the stone(s) followed by catheterization and drainage of the bladder may be needed. In some more severe cases, surgical removal by opening the penis/urethra may be needed. IV fluids and supportive care may also be required if kidney function has been compromised.
When the ureters, which bring urine from the kidneys to the bladder, insert into the lower urinary tract in an abnormal position it is called ectopic ureter(s). One or both ureters may be involved, and often the bladder is completely bypassed. Clinical signs include a constant urinary incontinence that begins at an early age, often before the cat reaches 6 months of age. Some cats will also urinate normally at times, while others may never exhibit normal urination. Diagnosis is based on the fact that a young cat is incontinent, physical examination, urinalysis, X-rays including dye studies of the entire urinary tract and exploratory surgery.
TREATMENT OF ECTOPIC URETERS
After infection and other conditions are ruled-out or treated, surgery is possible to correct the defect. A specialist or other surgeon skilled in this type of procedure should be sought, as the reconstruction is very delicate. Usually we wait until the cat is 4-6 months old.
URINARY INCONTINENCE (MICTURITION DISORDERS)
Loss of bladder control is an uncommon problem dealt with in cats. Incontinence would be considered as a loss of some degree of voluntary bladder control. The storage of urine and proper voiding is a complex mechanism involving several muscle and nerve groups. Dysfunction of any part of the system can result in bladder control being lost.
Most micturition disorders result from loss of nerve function or ectopic ureters, while cystitis, urolithiasis and other assorted problems with the muscles of the urethral passage can produce similar symptoms. The history will include the fact that the cat does go to the box and urinate normally, but where it lies a wet spot (sometimes large) is found. Other cats may dribble urine while seemingly unaware of the fact that anything is going on. Still other cases may involve an inability to urinate, total voiding when lifted or touched, straining to urinate and some abdominal pain. Certain drugs, which increase urinary output and overwhelm bladder storage capacity, can also produce a form of incontinence.
Cats with spinal cord disease, usually due to trauma, suffer from loss of control secondary to loss of the nerve function. Kittens with ectopic ureters will dribble urine from an early age. Diagnosis of this/these conditions is based on historical findings, physical examination, urinalysis, X-rays including dye studies, blood counts, serum chemical analysis and sometimes trial therapy with certain drugs. Most cats can be helped as long as spinal cord lesions are not present. A neurological exam may be necessary in these cases.
TREATMENT OF URINARY INCONTINENCE
Treatment for this disorder, if secondary to neurologic problems, will depend on how well the nervous system can recover and restore function. Cases of ectopic ureter will require surgery. Most other cases will respond to either hormonal therapy or treatment with drugs that improve the holding capabilities of various urinary system muscles. Most cats can be reasonably well treated.
RUPTURE OF THE URINARY BLADDER
The urinary bladder has quite a holding capacity and its thick wall can stretch greatly. Nevertheless, in cases of untreated urolithiasis, in cats with urethral obstruction or subsequent to traumatic injuries, the bladder may rupture. This leads to a urinary peritonitis and kidney failure as wastes that were being excreted from the body are now being recycled and building up in the blood more rapidly.
Clinical signs include abdominal pain, weakness, bloated abdomen, shock, vomiting, coma and death. Diagnosis is based on history, clinical signs, physical examination, X-rays, aspiration of abdominal fluid and exploratory surgery.
TREATMENT OF BLADDER RUPTURE
The abdomen must be opened, urine drained from the peritoneal cavity, and the defect repaired. The patency of the urethra must be re-established if it was plugged or damaged. The abdomen must be flushed and cleaned, and IV fluids and diuretic medications are used to flush the system of toxins and restart kidney function. The prognosis depends upon the degree of kidney damage or organ failure brought on by shock and the peritonitis.
FELINE LOWER URINARY TRACT SYNDROME (FELINE UROLOGIC SYNDROME (FUS))
The term FUS has been used to describe so many different conditions that in many ways, that it becomes essential to refine our terminology here. Feline Urologic Syndrome has been used to describe all cases of lower urinary tract disease where bloody urine and straining to urinate are prevalent symptoms. This means we are using FUS to denote feline lower urinary tract disease. Current understanding, however, would have us use the term to describe lower urinary tract disease of undetermined cause, only. Thus, FUS describes what is known as Feline Idiopathic Lower Urinary Tract Disease. (idiopathic means unknown cause)
When the symptoms of straining to urinate and blood in the urine are present, causes may include bacterial cystitis, tumors of the bladder, urolithiasis or smaller crystals in the urine, bladder trauma, mycoplasma infection, herpesvirus infection, and bladder defects. If no cause is found then we will say the cat has FUS. This diagnosis is made only after all other causes are ruled-out.
Some if not many veterinarians will use the term FUS to describe cats with cystitis, crystals in the urine or bladder stones. While this usage may not technically be correct, we should be slow to criticize due to long-standing disagreement on this terminology. Cats with FUS may or may not have lower urinary tract obstruction.
BLOCKED CATS: URINARY TRACT OBSTRUCTION
While not a separate or specific illness in and of itself, the blocked male cat is a condition unique and common to cats and is considered separately for this reason. All male cats have an anatomic peculiarity which makes them more susceptible to obstructions of the urinary tract in general; that being the urethra narrows, almost like a funnel, at the point where the urethra passes over the pelvis into the penis. In sufficient quantities, small stones, crystals, cells and other materials can lodge and easily plug the urethra. While females can contain the same debris in their urine, a large, somewhat strait urethra makes plugging unlikely.
Cats that become plugged most often have urolithiasis, FUS or cystitis in some form. Most often clinical signs appear suddenly and include making frequent attempts to urinate, an inability to pass much urine if any, weakness or staggering in the hind legs, a bloated abdomen, abdominal pain, collapse and death if untreated. Cats that die do so from acute renal failure or severe damage of the urinary bladder. Diagnosis is based on history, symptoms, physical examination, blood counts, serum chemistries, urinalysis and X-rays.
TREATMENT OF BLOCKED CATS
This condition constitutes a true urologic emergency and any male cat having any degree of trouble urinating should be examined immediately. Cats are lightly sedated and the cause of the blockage is flushed back into the bladder. A urinary catheter is generally sewn in place for several days while the cat is given IV or SQ fluids and urine output is carefully monitored. Repeated blood tests are used to access kidney function. Once it is determined the cat can safely urinate on its own again, the catheter is removed and long term treatment with special diets is most always advised or the problem will likely recur.
Some cats will either plug so severely or have damage to the urethra that creates further restrictions as to make normal urination impossible. In these cases, a perineal urethrostomy is performed, literally turning a male cat into an anatomical female and thus creating a urethral opening too big to become obstructed again. Most cats, fortunately, can be managed medically and with special diets.