At my barn, a 3 year old Percheron/Thouroughbred mare, Jazz, is getting introduced to riding. I've been working with her since she was 6 months old and abandoned at an auction. As far as I can see, she is such a sweet girl and naturally talented in dressage. One thing that I am worried might make things harder for her is her neck. Being half Percheron, her neck is a little short. Are there any ground excerisizes or anything I can do so she can flex it easier as she moves on her dressage career?