Q: This is an emergency that happens to male cats. The cat will make frequent trips to the litter box to urinate with straining which produces very little urine. They may become lethargic, have loss of appetite and vomit. When you feel there belly, you will feel a very large bladder.What is the name for this?
A: This is known as Feline Urinary Obstruction or blocked cat. This is a life threatening emergency so if your cat is showing any of these signs, the best thing to do is get them to a vet.
(Source- Pet Place)
This happens when sludge and crystals builds up in the male cat’s urethra blocking it so urine can’t get through. Urine builds up in the bladder. If not treated the kidneys stop working and toxins build up in the cat’s body.