Urethral Obstruction (Blocked Cat)

A urethral obstruction — often called a "blocked cat" — is one of the few genuine feline emergencies where the difference between survival and death is measured in hours. It occurs when something physically blocks the flow of urine out of the bladder. Because the urethra of a male cat is far longer and narrower than a female's, males (especially neutered males) are affected far more often.

When urine cannot escape, the bladder distends and becomes rock-hard and intensely painful. Waste products the kidneys would normally excrete — including potassium — accumulate rapidly in the bloodstream. Rising potassium slows and destabilises the heart, which is what ultimately kills an untreated blocked cat, sometimes within 24 to 48 hours of the obstruction becoming complete.

The early signs are easy to mistake for constipation: the cat makes repeated trips to the litter box, strains, crouches, and cries. Owners often assume the cat is constipated because the posture is identical. The crucial difference is urine output — a blocked cat produces little or nothing despite obvious effort. As the condition worsens the cat becomes lethargic, may vomit, stops eating, and eventually collapses.

Treatment is intensive but usually successful if started early. The cat is sedated so a catheter can be passed to flush out the blockage, and intravenous fluids are given to rehydrate the cat and drive down the toxic potassium level. The urinary catheter typically stays in place for a day or two. Cats that block once are prone to blocking again, so long-term management focuses on diet, hydration and stress reduction. In cats that re-obstruct repeatedly, a surgery called a perineal urethrostomy widens the urethral opening to prevent future crises.