Urinary Obstruction in Cats

This potentially fatal blockage of the urethra is most common in male cats who live indoors. Since females have a wider outflow tract, they may develop bladder infections with the same frequency as their male counterparts, but they very rarely become obstructed and therefore the condition is not life threatening for them. The blockage may occur suddenly or after your cat has exhibited the signs of bladder infection such as straining in the litter box with only small volumes of urine produced, bloody urine, or urinating in abnormal places—“out of box experiences”.

Just before the blockage occurs, you may see the following: decreased appetite, vomiting, straining to urinate, bloody urine, urinating outside the box, and vocalizations due to pain. These symptoms mimic those of urinary tract infections, but no urine is produced. As the blockage progresses and the bladder swells painfully, the signs worsen and include collapse, decreased body temperature and heart rate, severe dehydration, shock, and (in the worst cases) renal failure resulting in coma and death if treatment is not started soon enough. It only takes 24-48 hours for your cat to progress to this state, so early detection and treatment are critical.

The goals of therapy are to unblock the urethra with the passage of a urinary catheter while your cat is anesthetized, and then to provide fluid therapy by an intravenous catheter to flush the blood, kidneys, and bladder to eliminate the toxins that built up during the obstruction. The urinary catheter remains in place for 24-48 hours to allow the inflammation to subside in order to prevent immediate recurrence of the blockage once the catheter is removed. After removal of the urinary catheter, your cat will be observed for 4 to 24 hours to ensure that the urine flow has been reestablished, and your cat is urinating freely on his own. Some cats may remain irritated and will still strain for 1-2 days after catheter removal, so close monitoring at home to assess urine production is essential. We strongly recommend that you keep your cat indoors during this period for proper observation.

The crystals that are most commonly implicated in blockage are called struvite (triple phosphate) and are formed when the urinary pH is high (alkaline). Struvite crystal formation can be discouraged through the use of prescription diets and by early detection of any abnormality in your cat’s urinary habits. If stones and crystals are observed in your cat’s urine sample, Hill’s S/d diet (promoting the production of acid urine) may be prescribed for 1-2 months, after which your cat may be switched to Hill’s C/d for long-term maintenance. The veterinary prescription diets made by Purina and Eukanuba are acceptable alternatives. The over-the-counter “urinary tract health” diets, while somewhat helpful, are not adequate in these cases.

In addition to dietary management, frequent urinalyses are essential to screen for crystal formation, infections, and pH changes. After a blockage has occurred, we should recheck the urine, possibly including bacterial cultures, at 3 weeks, 2 months, 6 months, and then biannually or annually thereafter.

IF AT ANY TIME YOU ARE UNSURE IF YOUR MALE CAT IS URINATING FREELY OR IF HIS LITTERBOX BEHAVIOR HAS CHANGED, PLEASE CONTACT US IMMEDIATELY! After hours, be sure to contact the Capital District Animal Emergency Clinic at 785-1094—this condition requires immediate attention.

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