Thanks to all the wonderful people on this forum, I found out about HYPP I've heard about it before but was unaware it was also known as the Impressive Syndrom. My mare has Impressive in her 5th generation. She only has it on her dad's side, and she's clear on her mom's side (thank goodness). The person I bought her from never disclosed any information about her being HYPP N/N, N/H, H/H. I read Fancy's story and that just broke my heart. Vega is also 4 and I can't even imagine losing her. Does anyone have a horse out of Impress Me Shanon that was tested for HYPP?