Ureteral Obstruction in Cats

Ureteral obstruction occurs when one or both of the narrow tubes that carry urine from the kidneys to the bladder become blocked. In cats, this is most often caused by small stones that form in the kidney and become lodged as they travel down the ureter, though scar tissue, blood clots, or less commonly tumours can also create a blockage. The obstruction prevents urine from draining normally, and pressure can build back up into the affected kidney. Owners often notice reduced appetite, quiet behaviour, or vomiting that may seem vague at first. Some cats show discomfort in the abdomen or back, though this is not always obvious. The condition tends to develop over hours to days, and the signs can be subtle until the obstruction has been present for some time. It is more common in middle-aged to older cats, and some individuals form stones more readily than others. This page explores the patterns that may prompt investigation, what is happening inside the urinary tract when flow is interrupted, the imaging and tests used to identify and locate an obstruction, and the range of approaches—from medical management to surgical or minimally invasive procedures—that exist depending on the nature and duration of the blockage.