Hi Helen,

I  don't have an answer for you but am very interested to see any responses you get.  I just started my mare on Chasteberry this spring too and it  has helped with her shedding for sure.  But, her heats are just as you describe---atypical and extreme---her lot has another adjacent where another mare is kept, so her "buddy" is constantly there.  She also can get quite spooky.

Tina
4/2014  Santa Rosa, California
Honey Case History:  https://ecir.groups.io/g/CaseHistory/files/Tina%20and%20Honey  .
Photo Album:  https://ecir.groups.io/g/CaseHistory/album?id=36565  .