sit

1:At what age do i have to crop my Doberman's ears? He is 4 months already. 2: How can i teach my dog to sit from down? he gets confuse with the down and sit command. 3: Sometimes in the house he starts to run like crazy, how can i calm him down? Thanks.

I shot this little video this morning of Margot showing off how she's mastered the "sit" command. I just started teaching her "lie down" a couple days ago, but we still have a bit of work to do on that one. Anyway, I'm not really sure how to add a video in this forum, so I'm going to try...