Thanks everyone - I may be wrong but it feels like she is more anxious in open spaces than excited........?

I must admit I dont even bother with hacking out on the fields in the winter, I always stick to the railway track or road, dougal lites up when he even feels the grass under his feet and I agree, its probably the open spaces etc or, if the horse has been previously 'hunted' in the winter, then this seems to effect their behavior. Once, my horses are out 24.7 and they have a belly full of grass and the sun on their backs, then I go out accross the fields as they are much more calmer.

Am going to guess its because she can see more space and think ooooohh  Lots of place to run about then on a track its a bit more closed in so :-) hope this helped :-D
chloexx