I voted no also for 2 reasons: 1. if there is nothing the vet can do, it would make you feel awful. Plus drawing blood is not that comfortable for the poor animal.
2. Animals know when you are upset. Killian would know you were upset and that would upset him. Worry could get in the way of keeping him as healthy as possible for as long as possible.

I agree with everyone else. Love him and enjoy each minute you have together. That will go a long way in making him as healthy as possible. My prayers are with you both always.