Thank you everyone, for your responses!
My GSD came into heat the other day (when I first wrote on this thread). She is like a clock every 6 months (she has never been bred), so I wondered if Anthea would soon be following her. And she did - her first heat started yesterday. I think it will be a long week for my poor male, Roni. He misses his women!
Now I think I have some idea of what to expect!
Marcy