What a fantastic experience. One with a pack of dogs in nature. There are several companies which organise dog sledding. We strongly recommend booking this activity well in advance. Especially over Christmas/NY and mid-term weeks the dog sledding is an extremely popular activity.
There are several companies and we found “Tanaka Camp” the absolute best. This camp moves around, so you may have to drive to the other side of the valley towards Ste Foy Tarentaise, but it is absolutely worth it.
Closer to home there is “Le Trappeur” in the village of Nancroix (down from Peisey&Vallandry).
In La Plagne there are several. Please consult the La Plagne website.