According to this ad, the pups that worked on the Game of Thrones pilot
are were for sale. Assuming the ad is correct, they used Siberian Huskys to stand-in for direwolf pups.
Fantastic litter of pups. MOVIE STAR PUPS,have been filmed in the fantasy adventure ‘GAME OF THRONES’ as orphaned wolf pups featuring the famous actor SEAN BEAN aka the hobbit from Lord Of The Rings. Come and pick one of these stars to be part of your family at a bargain price.1 STUNNING BLUE EYED DOG PUP LEFT, charcoal/wolf grey and white, Pure bred but NOT REGISTERED. Both parents can be seen. pup will be wormed to date. Ready to go to his new home NOW!!!
[Thanks to Daniel for the link!]