Max was neuterd last month at 10months old too and I had all the same concerns you have. I was sooo worried and also sad to put him through the sugery. The sugery was a success of course, he was up and running that same night. He never slowed down, he was same ol Max.. Except, the Good news is!!! No more marking in the house, and he is such a good boy now. He was a good boy before, but a little crazy, now he is just a sweet baby. I am so glad I did it, and so glad its over with. You are making the right desicion for Sebi, be strong we are all here for you
Dont worry, he will be just fine. He will be up and running the next day and you will be amazed at how fast be bounces back