If you're concerned about growth plate injuries your best best is to have your vet do a quick xray. It's so hard to estimate when a dog's growth plates have closed; given the fact that he's medium sized I'd guess they'll be done around 1 year of age.

I don't know if the impact on snow makes a difference; I know you're not supposed to run long distances with young dogs on hard surfaces.

 

18 months before serious excursions. Especially since he's smaller so you'll have to help a lot. Dogs can pull about 2-3 times their weight flat out but this can be mitigated when biking, scootering, or skiing since the person being pulled can take some of the pressure off the dog.
I do short little skijor runs (MAYBE a half mile at MOST) with my 42lb 8 month old Spaniel, but I would do more than that. She's also well conditioned which helps a lot. @zoorun, want to weigh in?

 

Oh my goodness, Alaskan Huskies are awesome! I would love one someday. Most mushers start dogs at about 12 months for training and yeah, I would wait until 18 months for anything serious. 9 months is a good time to be training line out, ger, haw, stop etc though! If he's from working lineage he likely won't need much work training to actually pull I think low impact stuff will be fine though for now.

 

Oh my goodness, Alaskan Huskies are awesome!

Yep, they're pretty cool

 

Thanks everyone! Just for clarification: The reason we need to wait until 18 months is because he will have completely stopped growing and "filling out" by then, correct?

 

It's so his growth plates fully close in order to prevent injury to his joints. :thumbsup: