I only started giving it to Raf because he had that terrible mud fever caused by e coli and enterococcus that wouldn't clear up despite repeated courses of different antibiotics and steroids. I was searching for something to boost his immune system and came across the info on vitamin e. I think some horses can store it better than others but I did read that cushings horses are particularly likely to need supplementing - maybe they can't store it so well?
Anyway, not only did Raf's infection magically clear up but since then he has held his condition in winter, whereas before he always used to lose muscle and be quite sickly
.
What I'm trying to say in my long winded way (sorry!) is that you can probably tell by Chloe's general condition (and whether she loses condition when she's not getting much grass) as to whether or not she would benefit from a vit e top up.