He manages to keep them short on his own. Probably due to how stubborn he is on walks at times (really digs into the asphalt/concrete).
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My girl Shaye is the same - - she's now 3, and I'm trying the Gentle Leader. Her "sister" Gemma is settling into it quite nicely, not pulling any more - Shaye still throws herself on the ground, digs her face into the dirt, lays down and won't get up - won't pee or poo on walks - obviously it's going to take longer for her to decide to just cooperate with it. She will or she won't, I can't have her digging and pulling constantly, my hands are nearly useless from it.