Urinary Tract Obstruction
TREATMENT OF FELINE URINARY TRACT OBSTRUCTION
Feline lower urinary tract disease (formerly called feline urological syndrome - F.U.S.) can be life threatening. Feline lower urinary tract disease becomes life threatening under those conditions when mineral crystals form in the urinary bladder, aggregate with various organic moleules, form plugs and then lodge in the terminal urethra of the penis. When complete obstruction exceeds twenty-four hours the animal rapidly deteriorates, becomes poisoned by his own waste products and then dies. Females have an equal amount of urinary tract disease but it is the male who becomes obstructed.
CAUSES
The causes of feline lower urinary tract disease have not been clearly established although numerous factors have been implicated. Among these are hygiene of the litterbox (e.g. soiled litter in a multicat household), viruses, bacteria, obesity, middle-age and dietary factors such as high magnesium intake. Magnesium is a component of "ash". Ash per se is not the cause of urolithiasis, urinary tract stone formation, but several of its components, such as magnesium, have some bearing on it.
CLINICAL PRESENTATION
Cats with feline lower urinary tract disease are often presented to veterinary hospitals because of straining in the litterbox, some hematuria (blood in the urine), pollakiuria (frequent attempts at urination), and licking of the penis. The most common owner complaint, however, is that the cat appears to be constipated which he is not. He is either straining to urinate and cannot or feels the need to urinate even though his bladder is empty.
Urinary obstruction for 12 hours or longer constitutes an emergency. Many cats that have had urinary blockage longer than 24 hours have the following clinical signs: vomiting, metabolic acidosis, severe dehydration, hypothermia, cardiac arrhythmia, elevated serum urea nitrogen and creatinine, and hyperkalemia. Some cats are comatose and unresponsive to painful stimuli on presentation.
INITIAL MANAGEMENT
The primary objective in the treatment of a cat with urinary tract obstruction is to relieve the obstruction and re-establish normal urine flow. Additionally one seeks to support the kidneys and cardiovascular system which may have been compromised by the obstruction. This is most commonly done with intravenous fluids.
Most cats are heavily sedated or anesthetized to allow removal of the obstructing urethral plugs and insertion of a urinary catheter. The anesthetic is selected with attention to the nature of the signs the cat is showing. If the kidney function is severely compromised one selects anesthetics less dependent on kidney function for elimination.
Once sedated or anesthetized an attempt is made to remove obstructing crystalline/mucus plugs through hydropropulsion. This is accomplished by use of a smooth blunt-tipped metal cannula emitting a stream of normal saline solution under pressure of a large syringe or gravity through an intravenous line connected to an intravenous fluid source. One tries to dilate the penile urethra with saline so that the fluid will either break up the uroliths and flush them past the cannula and out the penis or propel them back into the bladder.
If hydropropulsion does not clear the urethra and all other options except surgery have failed to alleviate the blocakge and remove urine from the animal cystocentesis may be performed. The urinary bladder may be evacuated with a syringe and small guage needle. In addition to the above treatments various other medications may be used to treat increased blood potassium, acidosis, renal failure etc. If hydropropulsion is successful one has the option to install an indwelling urinary catheter or not.
USE AND CARE OF INDWELLING URINARY CATHETERS
The advantage of a urinary catheter is that it allows instillation of various medications and fluids to dilute and remove debris, to disinfect the urinary bladder, to instill antibiotics, antiseptics and anti-inflammatory drugs. One may suture the catheter in place to insure continued drainage while the animal recovers. Among the disadvantages of an indwelling urinary catheter are that they need to be protected from the cat, and may require use of an Elizabethan collar. Catheters also serve as an avenue of infection and they are irritating to the urinary bladder and the already traumatized urethra.
These problems are avoided if one does not use a urinary catheter after the bladder has been emptied and treated. However, if the cat becomes reobstructed either by more debris or by swelling or spasm of the urethra then the whole catheterization procedure must be repeated.
LABORATORY TESTS
Lab tests are often recommended to assess the state of the kidneys, check for urinary tract infections and investigate other concurrent disease conditions which may or may not be related to the urinary problem.
MAINTENANCE THERAPY
After the urinary catheter has been removed the cat sis often hospitalized an additional 24 hours to check the muscle tone of the bladder. Many cats who are obstructed and whose urinary bladder becomes distended lose bladder tone and the ability to urinate voluntarily. If the cat is unable to urinate by himself gentle compression of the bladder will help empty the bladder of accumulated urine. Owners who are well motivated can learn to do this as well.
If bladder tone does not rapidly return several drugs may be used to assist the process. Bethanecol chloride, an anticholinergic agent, is used to increase bladder tone. Other drugs are used in an effort to decrease smooth muscle tone in the urethra in the event that urethral spasms are inhibiting urine outflow.
DIETARY MANAGEMENT
The object of nutritonal management of cats with lower urinary tract disease is to
assist recovery and help avoid recurrence. The initial step is to change the diet to a product that is formulated to facilitate dissolution of struvite crystals in urine, e.g., Prescription Diet Feline s/d. Following a month or two of satisfactory recovery time many animals are switched to a maintenance diet such as Prescription Diet c/d. This diet is not as severely restrictive as s/d but is formulated to discourage mineral crystal formation.
SURGICAL MANAGEMENT
In those situations where a male cat becomes obstructed over and over again surgery is sometimes recommended. The procedure is called a perineal urethrostomy. The procedure removes the penis and establishes a urethral opening nearly as wide as that in a female. The thought behind the surgery is that even if the tendency to form crystal and mucus plugs cannot be controlled then obstruction, at least, can be prevented by making the urethral opening very large. These surgeries are generally successful but when they do fail it is usually because of the build of of scar tissue or stricture of the urethra which once again narrows the opening.
TREATMENT CONTROVERSY
Both medical and dietary treatment of these conditions are controversial. The first controversy regards whether we are treating a single inflammatory disorder of the urinary tract or many different disorders that just appear similar. Controversy also revolves around the use of medication. Some veterinarians always use antibiotics even in the absence of demonstrable infection, some veterinarians use corticosteroids in the bladder, orally or by injection, some use urinary acidifiers, smooth muscle relaxers, skeletal muscle stimulators, urinary antiseptics or nothing at all. Also controversial is the question of whether to use an indwelling catheter after removal of the obstruction and then whether to use a closed or open urinary drainage systems. The final controversy regards the use of dietary treatment. Some authorities think it is indispensable and others that it is ineffective. Clearly the above controversies exist because causes of feline urinary tract inflammation are not definitively known and effectiveness of treatment has been difficult to measure.
SUMMARY
Although the causes of feline lower urinary tract disease are incompletely understood urinary tract obstruction is itself treatable and clearly an emergency. Most veterinarians agree on the necessity of removal of the obstructing plug and the importance of intravenous fluid therapy to dilute the urine, remove accumulated toxins, re-establish normal electrolyte balance and minimize kidney damage.
Note: You can assume that no two veterinarians will treat this problem identically and each will have strong and differing feelings on causes and treatment. This is normal. If you put two honest veterinarians in a room and give them a problem you will get five answers between them.
© Copyright 2008, David Joseph, RVT and Matthew J. Ehrenberg, DVM
Top
Feline lower urinary tract disease (formerly called feline urological syndrome - F.U.S.) can be life threatening. Feline lower urinary tract disease becomes life threatening under those conditions when mineral crystals form in the urinary bladder, aggregate with various organic moleules, form plugs and then lodge in the terminal urethra of the penis. When complete obstruction exceeds twenty-four hours the animal rapidly deteriorates, becomes poisoned by his own waste products and then dies. Females have an equal amount of urinary tract disease but it is the male who becomes obstructed.
CAUSES
The causes of feline lower urinary tract disease have not been clearly established although numerous factors have been implicated. Among these are hygiene of the litterbox (e.g. soiled litter in a multicat household), viruses, bacteria, obesity, middle-age and dietary factors such as high magnesium intake. Magnesium is a component of "ash". Ash per se is not the cause of urolithiasis, urinary tract stone formation, but several of its components, such as magnesium, have some bearing on it.
CLINICAL PRESENTATION
Cats with feline lower urinary tract disease are often presented to veterinary hospitals because of straining in the litterbox, some hematuria (blood in the urine), pollakiuria (frequent attempts at urination), and licking of the penis. The most common owner complaint, however, is that the cat appears to be constipated which he is not. He is either straining to urinate and cannot or feels the need to urinate even though his bladder is empty.
Urinary obstruction for 12 hours or longer constitutes an emergency. Many cats that have had urinary blockage longer than 24 hours have the following clinical signs: vomiting, metabolic acidosis, severe dehydration, hypothermia, cardiac arrhythmia, elevated serum urea nitrogen and creatinine, and hyperkalemia. Some cats are comatose and unresponsive to painful stimuli on presentation.
INITIAL MANAGEMENT
The primary objective in the treatment of a cat with urinary tract obstruction is to relieve the obstruction and re-establish normal urine flow. Additionally one seeks to support the kidneys and cardiovascular system which may have been compromised by the obstruction. This is most commonly done with intravenous fluids.
Most cats are heavily sedated or anesthetized to allow removal of the obstructing urethral plugs and insertion of a urinary catheter. The anesthetic is selected with attention to the nature of the signs the cat is showing. If the kidney function is severely compromised one selects anesthetics less dependent on kidney function for elimination.
Once sedated or anesthetized an attempt is made to remove obstructing crystalline/mucus plugs through hydropropulsion. This is accomplished by use of a smooth blunt-tipped metal cannula emitting a stream of normal saline solution under pressure of a large syringe or gravity through an intravenous line connected to an intravenous fluid source. One tries to dilate the penile urethra with saline so that the fluid will either break up the uroliths and flush them past the cannula and out the penis or propel them back into the bladder.
If hydropropulsion does not clear the urethra and all other options except surgery have failed to alleviate the blocakge and remove urine from the animal cystocentesis may be performed. The urinary bladder may be evacuated with a syringe and small guage needle. In addition to the above treatments various other medications may be used to treat increased blood potassium, acidosis, renal failure etc. If hydropropulsion is successful one has the option to install an indwelling urinary catheter or not.
USE AND CARE OF INDWELLING URINARY CATHETERS
The advantage of a urinary catheter is that it allows instillation of various medications and fluids to dilute and remove debris, to disinfect the urinary bladder, to instill antibiotics, antiseptics and anti-inflammatory drugs. One may suture the catheter in place to insure continued drainage while the animal recovers. Among the disadvantages of an indwelling urinary catheter are that they need to be protected from the cat, and may require use of an Elizabethan collar. Catheters also serve as an avenue of infection and they are irritating to the urinary bladder and the already traumatized urethra.
These problems are avoided if one does not use a urinary catheter after the bladder has been emptied and treated. However, if the cat becomes reobstructed either by more debris or by swelling or spasm of the urethra then the whole catheterization procedure must be repeated.
LABORATORY TESTS
Lab tests are often recommended to assess the state of the kidneys, check for urinary tract infections and investigate other concurrent disease conditions which may or may not be related to the urinary problem.
MAINTENANCE THERAPY
After the urinary catheter has been removed the cat sis often hospitalized an additional 24 hours to check the muscle tone of the bladder. Many cats who are obstructed and whose urinary bladder becomes distended lose bladder tone and the ability to urinate voluntarily. If the cat is unable to urinate by himself gentle compression of the bladder will help empty the bladder of accumulated urine. Owners who are well motivated can learn to do this as well.
If bladder tone does not rapidly return several drugs may be used to assist the process. Bethanecol chloride, an anticholinergic agent, is used to increase bladder tone. Other drugs are used in an effort to decrease smooth muscle tone in the urethra in the event that urethral spasms are inhibiting urine outflow.
DIETARY MANAGEMENT
The object of nutritonal management of cats with lower urinary tract disease is to
assist recovery and help avoid recurrence. The initial step is to change the diet to a product that is formulated to facilitate dissolution of struvite crystals in urine, e.g., Prescription Diet Feline s/d. Following a month or two of satisfactory recovery time many animals are switched to a maintenance diet such as Prescription Diet c/d. This diet is not as severely restrictive as s/d but is formulated to discourage mineral crystal formation.
SURGICAL MANAGEMENT
In those situations where a male cat becomes obstructed over and over again surgery is sometimes recommended. The procedure is called a perineal urethrostomy. The procedure removes the penis and establishes a urethral opening nearly as wide as that in a female. The thought behind the surgery is that even if the tendency to form crystal and mucus plugs cannot be controlled then obstruction, at least, can be prevented by making the urethral opening very large. These surgeries are generally successful but when they do fail it is usually because of the build of of scar tissue or stricture of the urethra which once again narrows the opening.
TREATMENT CONTROVERSY
Both medical and dietary treatment of these conditions are controversial. The first controversy regards whether we are treating a single inflammatory disorder of the urinary tract or many different disorders that just appear similar. Controversy also revolves around the use of medication. Some veterinarians always use antibiotics even in the absence of demonstrable infection, some veterinarians use corticosteroids in the bladder, orally or by injection, some use urinary acidifiers, smooth muscle relaxers, skeletal muscle stimulators, urinary antiseptics or nothing at all. Also controversial is the question of whether to use an indwelling catheter after removal of the obstruction and then whether to use a closed or open urinary drainage systems. The final controversy regards the use of dietary treatment. Some authorities think it is indispensable and others that it is ineffective. Clearly the above controversies exist because causes of feline urinary tract inflammation are not definitively known and effectiveness of treatment has been difficult to measure.
SUMMARY
Although the causes of feline lower urinary tract disease are incompletely understood urinary tract obstruction is itself treatable and clearly an emergency. Most veterinarians agree on the necessity of removal of the obstructing plug and the importance of intravenous fluid therapy to dilute the urine, remove accumulated toxins, re-establish normal electrolyte balance and minimize kidney damage.
Note: You can assume that no two veterinarians will treat this problem identically and each will have strong and differing feelings on causes and treatment. This is normal. If you put two honest veterinarians in a room and give them a problem you will get five answers between them.
© Copyright 2008, David Joseph, RVT and Matthew J. Ehrenberg, DVM