Ahhh…but there is sort of a way for you to go dog sledding and both do an excursion and your partner not have to pay for/or do the dog sledding part!
Even though it is far better & more fun to do dog sledding on snow (as opposed to a dry land/wheeled sled) it seems that there are no dog sledding excursions being offered on snow (unless I missed it).
The options I saw for dog sledding (both dry land/wheeled sled) were…in Juneau - Sled Dog Discovery & Musher's Camp - 2¾ Hours - $134.95 per person…and in Skagway - Musher's Camp & Sled Dog Experience - 3¼ Hours - $129.95 per person
Here's how to do it…there's an all day train ride in Skagway that goes up to Caribou Crossing (aka Carcross)…cute little town (very small!).
It's called the Yukon Expedition & White Pass Railway - 8 Hours - $199.95 per person
They also have a musher's camp there (dry land/wheeled sledding). Ed and Michelle (both have done the Yukon Quest and the Iditarod) run it…besides the cost of the train I think it's like $60 for the dog sled ride. And there'll be plenty of other Olivians for your partner to stay with while you're on the sled ride…besides they usually have puppies around!!
That way you can do a train excursion (and dog sled ride) in Skagway and do what's great to do in Juneau…go whale watching!!!
Hope that helps…