ByJohnathan Elliott DVM
Urethral obstruction in cats is a common and serious emergency that is seen primarily inmale cats, but obstruction can occur in female cats. It is fatal if urine flow is not restored within 24-48 hours. Typically cats present on emergency with a history of lethargy, depression, anorexia, and being uncomfortable in their abdominal area. There is also a prior history of straining to urinate, painful urination, urinating more frequently, and blood in the urine. Cats may also urinate “inappropriately” outside the litter box or in unusual locations.
Urethral obstruction can occur due to stones, sediment, or tumors. Typically male cats have a urethral “plug” composed of crystals and mucous that lodge in the penis. Once the penis has become obstructed, it acts like a dam in a river, and causes back pressure that extends from the bladder to the kidneys. The resulting dysfunction of the kidney leads to decreased sodium and water reabsorption and excretion of potassium and acids. The end result is acute renal failure and increases in potassium causing cardiac arrest.
Physical examination of these cats reveals a large, firm, painful bladder. Depending on the duration of obstruction, they may be recumbent, have a low heart rate, and possibly be in a coma. Palpation of firm bladder, with history is very supportive but radiographs can reveal certain types of stones in the bladder or urethra.
Immediate treatment involves IV fluids and relieving the blockage by passage of a urinary catheter. Laboratory analysis of blood and urine is necessary to assess the severity of kidney injury and in order to treat electrolyte abnormalities. Aggressive fluid therapy is critical to reestablish normal hydration and kidney function. Cats are typically hospitalized for a few days but surgery is recommended for cats with recurrent obstructions, urethral trauma, or when urethral stones are present.
With correct initial management, the short term prognosis for resolving the obstruction and correcting metabolic abnormalities is good. Cats that have had long standing obstruction carry a poorer prognosis than those of shorter duration. Recognizing the signs of feline urethral obstruction is very important and can mean the difference between life and death in our feline friends.
Additional information
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Adapted from The Feline Patient by Gary Norsworthy, et al.