). We've always considered her pre-brother behavior her "base line" since it's been this way all her life. And even though her hunger has always returned after her periods, her lethargy seems to remain low now except for the occasional energetic day (one day a week or so). Since her brother appeared, however, her cycles have changed to once every 3-4 months and she is even more lethargic than usual despite the fact that I spend about the same amount of time with her as I do him, maybe more, and we walk together (just the two of us) every day. Also, she has gained about 5 pounds in the last 2-3 months. I don't think her issue is depression as she remains bright-eyed and happy when we're together and we spend no more/less time together pre-brother as we do post. She still plays with her brother but not as often and not as energetically. 
What I recall of my GSD crosses at that age, is that it's about then that they gave up the last of their 'puppyish' behaviour. I wouldn't have said they were any less energetic though - it just wasn't directed to play. But then, they were all working farm dogs, so that may have factored in.
As far as I'm aware, GSD's aren't any different than other breeds regarding their menstrual cycles. Combine that change with decreased energy, and I'd suggest that a vet visit may be in order to rule out any underlying causes.
As far as I'm aware, GSD's aren't any different than other breeds regarding their menstrual cycles. Combine that change with decreased energy, and I'd suggest that a vet visit may be in order to rule out any underlying causes.
