This is a very common problem in male cats and can be lethal very quickly if not addressed right away. The most common clinical signs of obstruction are straining (squatting to urinate) with very little urine being passed, howling or vocalizing, lethargy, or other indications your cat is in pain.
Male cats have a very long, narrow urethra to urinate from. The urethra is the tube that comes from the bladder through the penis that allows normal urination. This narrow tube can easily become obstructed with all kinds of debris such as crystals, inflammatory debris or stones.
When the urethra becomes obstructed, the cat cannot urinate. An obstruction starts off only being uncomfortable and quickly becomes very painful as the urine completely fills the bladder. Eventually the urine is backed up all the way to the kidneys, which is extremely painful. This is a big problem because the kidney has the important job of excreting waste, particularly potassium. When urine can no longer be made, potassium can very quickly rise to dangerous levels.
The blood potassium, because it is a positively charged ion, affects the electrical activity of the heart. A normal blood potassium level is about 4 meq/L. When the level reaches 7 or above, arrhythmias (abnormal electrical activity of the heart) and acidosis can occur. When the blood level reaches close to 10, the heart can actually stop. This may only take hours to occur.
When an obstruction occurs, your cat should be taken to the veterinarian immediately to have the obstruction relieved, be put on pain medications and IV fluids and to be very closely monitored until blood potassium returns to normal. Often a urinary test is recommended to see if there are any underlying conditions. For cats that have had one obstruction, 50% will likely have another occurrence. If a cat repeatedly experiences obstructions, surgery may be recommended.
This disease may be prevented by a couple simple steps you can take at home. First, always make sure your cat has access to water. Increasing water intake will decrease how concentrated the urine is and may decrease crystal formation- so have multiple bowls of available! Offering your cat wet food may also increase its water consumption because wet food contains a large percentage of water.
It might be a good idea to discuss a urine test with your veterinarian at your cat’s next regular checkup. This may identify cystitis (inflammation of the bladder), crystal formation, stone formation or evidence of infection.