My GSD (now 4 yrs old) had no interest in playing with other dogs. He is still aloof when it comes to other dogs. He just doesn't want to be a social butterfly.
He is not dog aggressive. There is a big difference.
Hondo Von Dopplet L Bauernhof "Hondo"- GSD
Lilie's Tug McGraw "Tug" - Golden Retriever
Maggie - Mini Dachshund (Rescue)
Lonestar Pivo - Texas Blue Lacy
Ashe - Barn Cat
Katie / APHA