Also known as ischuria, a urinary obstruction (UO) is a medical emergency requiring immediate treatment. It occurs when the flow or urine is blocked anywhere along the urinary tract.
The most common cause is a urinary plug which contains protein, cellular debris, and crystals (commonly struvite). Other causes include congenital abnormality, inflammation (urethritis), lesions, tumours or clots. Males are more prone to developing a urinary obstruction than females due to their longer and narrower urethra. However, females can also be affected.
Urinary blockages can occur slowly, over a period of time, or very suddenly. Left untreated, an obstruction can lead to a ruptured bladder and kidney failure. As the kidneys are no longer functioning as they should, toxic levels of nitrogenous waste products (uremia) and potassium (hyperkalemia) build up in the blood.
A distended bladder can cause the bladder to lose its tone (bladder atony), resulting in urinary incontinence which may be permanent.
What are the symptoms of a urethral obstruction?
- Inability to urinate (any pet owners confuse this with constipation).
- Weak flow of urine.
- Urinating in inappropriate locations.
- Blood in urine (hematuria).
- Genital licking.
- Sand like material at the tip of the penis.
- Crying when trying to go to the toilet.
- Abdominal pain.
- Abdominal swelling.
Additional symptoms may occur as the kidneys fail and toxins build up in the blood. These may include vomiting, loss of appetite, weakness, lethargy, abnormal heart rhythm, and ultimately collapse.
How is a urinary obstruction diagnosed?
Your veterinarian should be able to make a tentative diagnosis based on presenting symptoms. He will perform a complete physical examination, at which time he will be able to feel a firm, full bladder, there will also be abdominal pain or discomfort.
He will need to run some diagnostic tests to determine the cause and to establish if any damage has occurred to the kidneys. Some tests may include:
- Blood profiles to check blood potassium, creatinine and nitrogen levels and assess the kidneys for damage.
- X-ray or ultrasound to evaluate for stones, congenital abnormalities, and tumours.
- ECG (electrocardiogram) to monitor heart rhythm.
How is a urinary obstruction treated?
The first priority is to correct mineral imbalances in your cat. Treating hyperkalemia with sodium bicarbonate, insulin/dextrose or calcium gluconate.
Removing the blockage. Your veterinarian may be able to manually express urine, or if this is not possible, by inserting a needle through the abdomen and into the bladder and withdrawing the urine. Catheterisation may be used to relieve the obstruction and continued for several days afterwards. Anesthesia will be required to catheterise the cat, which involves the insertion of a thin tube into the penis and up to the bladder. A sterile solution is flushed through the tube to push the obstruction back into the bladder, where it will dissolve.
If the blockage can't be relieved via the methods listed above, an emergency perineal urethrostomy will be performed. This involves surgery to create a new urethral opening.
IV fluids to correct electrolyte imbalances and treat dehydration.
Once the obstruction has been removed, the kidneys are able to resume their job of urine production, removing toxins from the bloodstream. In the days after, urine production is increased as the kidneys clean the blood. This is known as post obstructive diuresis. Intravenous fluids will be continued to prevent your cat from becoming dehydrated and developing hypokalemia (low blood potassium) as a result of increased urine output.
During this time, the catheter remains in place, urine output is carefully monitored by your veterinarian.
Painkillers may be prescribed to your cat while he is undergoing treatment.
If an infection is present, antibiotics will be administered.
Addressing the underlying cause will be necessary to prevent future occurrences. Increasing water consumption to dilute the urine is strongly recommended. Feeding a canned or raw diet may be recommended as this contains a higher amount of water than dry food.
Alternatively, a prescription diet may be recommended to help dissolve crystals and stones.