Shih Tzu Wetting the bed

Question
I am beyond frustrated. I feel like I'm doing everything in my power, but my 8mo. old Shih Tzu randomly wets the bed. This morning, I awoke at 2:30 am to find him jumping around, which usually indicates that he needs to go outside. Well, too late, there was a massive puddle of urine in my bed. He has done this several times since I got him. It's always the same place. I've treated the matress, flipped it over, taken away my mattress pad, bought a plastic mattress protector. I don't let him drink anything after 10pm. We go outside literally right before bed time. What am I doing wrong? He is scheduled for neutering on the 24th of this month... but I don't know how much longer I can take this. :(

Answer
How late do you go to bed, Chelsie? Generally, I recommend taking water up 3 hours before bedtime. That's around 7:00pm at my house. Then, make sure to take the dog out not only right before bedtime, but somewhere in between, too, just to make sure that he's emptying his bladder completely. When you take him out, put him on a leash so you can keep him from getting distracted, and so you can ensure that he has, in fact, gone potty.

Another solution would be to simply crate him at night.