Urinary Blockage in Cats
written by: Tannis Baxter, DVM
A call comes into the Guardian Veterinary Centre at 3am from a concerned cat owner...."My cat is yowling in the litter box, he really appears uncomfortable...I think he might be constipated". Although we do see a large number of constipated cats through our emergency service, this question is associated all too commonly with a condition called a feline urinary blockage. A blockage can occur when mucus, crystals or small bladder stones form a plug in the urethra preventing the passage of a normal urine stream. Typically male cats are affected because their urethral diameter is extremely small. On presentation some cats can pass drops of urine while others have complete urinary obstruction. Both have the potential to be life threatening if the condition is not recognized.
Urinary blockage is one part of a condition called feline lower urinary tract disease (FLUTD) that is typified by bloody urine, straining to urinate, urinating in unusual places (kitchen/bathroom sink or bathtub) and/or constantly grooming the back end due to irritation. Once the plug has severely limited or blocked the outflow of urine, bladder distention from urine and increased pressure on the urethra, ureters and kidneys can cause extreme discomfort. Kidneys which receive this ongoing pressure become damaged releasing increased amounts of kidney enzymes and an electrolyte called potassium into the blood stream which can interfere with the normal heart function.
Once at the Guardian Veterinary Centre the cat is examined by a veterinarian and the bladder is initially palpated. Typically, a normal cat's bladder is either soft (like a water balloon), small or empty. A blocked cat's bladder is medium to large, round, very firm, and painful to the touch. In some instances the urinary opening will appear bloody, bruised or have sand/grit on the surrounding fur (indicating crystals). The cat may also have a low heart rate associated with a high potassium requiring a tracing (also called and electrocardiogram or ECG) and intital treatment to stabilize the heart.
Pain associated with this condition is immense and an injection of pain medication is usually administered. Once stable and pain control is on board, the cat is prepared for anesthesia. An intravenous catheter is placed and attached to intravenous fluids. These fluids are vital to ensure proper blood pressure during anesthesia and a hallmark in the future treatment by rehydrating the cat as well as flushing the bladder and kidneys. Blood work is collected to provide information on initial kidney damage, blood potassium level, and other values which dictate the type of anesthetics, treatment and a cat's response to treatment over the next few days.
Once under anesthesia a well lubricated, small urinary catheter is carefully inserted through the urethral opening. If the catheter can no longer be advanced, water is gently pulsed through the catheter to dislodge the plug and flush it into the bladder. Initially a urine sample is collected to check for crystals, inflammation, abnormal cells and/or bacteria. A sample is also sent to the laboratory for a culture and sensitivity to look for bacteria and determine, if present, which types of antibiotics will work best (although to most client's suprise this condition does not usually involve an infection). X-rays may also be taken to check for visible bladder stones requiring ongoing treatment or surgical removal. Next the bladder is completely drained of urine and flushed copiously with water to get rid of as much sand and/ or debris as possible.
A soft urinary catheter is kept in place an average of 1-3 days to allow ongoing debris and bloody urine to be flushed from the bladder. The hydration of the cat, kidney enzymes and potassium are also closely monitored to ensure they are returning to normal levels. A prescription diet is given to help rebalance the urine, dissolve any remaining crystals (if present) and prevent their return. In some instances a prescription diet may be recommended for the remainder of their life. Once the amount of blood in the urine has decreased (light pink or clear) "the moment of truth" arrives where the catheter is pulled and we wait anxiously for the cat to pass a good stream of urine. Oral medications for pain and to relax the urethra (as it has a tendency to spasm with discomfort limiting urination) are also administered. Once a good stream of urine is consistently produced, the cat is discharged.
Once at home urination should be closely monitored by the owner. If the cat is dribbling small amounts or straining to urinate they need to be re-examined by a veterinarian as there is a potential to "re-block". This can be the most frustrating part of the condition for me as a veterinarian, as a small population of cats despite aggressive treatment can have complications requiring additional treatment such as re-catheterization or a surgical procedure called a perineal urethrostomy where the urethral diameter is widened.
A lot of owner's ask me "what causes this condition"? Unfortunately there is no straightforward answer. A number of factors can be responsible including genetics, environment and diet. It can be a difficult and frustrating disease for both the client and veterinarian but treatment and education are pivotal throughout the treatment process for the best possible outcome.