Hope he's OK. Charlie is the same age, 9 months, and I'm thinking that maybe he should now be neutered as he's getting a bit boisterous and running away on walks! Do you think this is the right age? I read on previous threads that after 18 months is best- what made you go for this age?
I wouldn't rely on neutering to solve any behavioural/training issues - it is not a quick fix solution; sometimes it works for some behaviours, more often it doesn't
Molo was a total nightmare for recall when he was a teen - I used a long line for nearly 12 months, and held off neutering him......he is still entire, and comes back fine now
Similarly, boisterous behaviour is age related; and certainly won't be cured by neutering
I hope Zack recovers well - are you planning on camping on the sofa with him tonight ?