Straining to eliminate can be a sign of a life-threatening urinary blockage in male cats. If you have a male cat and are not sure that he is able to COMPLETELY EMPTY his bladder, he should see a vet ASAP. It would be very rare for a female cat to have a urinary obstruction. Straining can also be a sign of a urinary tract infection, inflammation, and even constipation. Straining typically indicates pain, so be sure your cat’s condition is diagnosed by a vet.