yes it is an emergency situation!!!! get him to a Vet asap....his bladder tube has a blockage like Apple suggested and when completely blocked like this the bladder will continue to fill and than burst....he is in pain, he is just not showing it right now. please rush him to a clinic asap
Yep, it can be serious.My girl is 6 yo and the fact she was not peeing as usual was caused by a stone in her bladder- surgical situation
But cant be just a sign of infection also - what means vet care as well
Take your boy to the vet soon - cats are pretty damn tough and wont show suffering til to be very late.
Mine was under urinary infection medicationfor some months til we get the USound and discover the struvite stone...
Good lucky and a good recover for the cat