Why is it 10 mins box walk?

[Gingerwitch]

Just wondered why the figure of 10 mins is usually given out? I pretty much keep to what my vets tell me and do the 10 mins - well sometimes its 12 if we stop for a nibble of grass- but have seen people who have been told 10 mins walk in hand have done - 20 mins twice a day and then let em graze in hand for upto an hour. I have also seen folks trot up their box rest horse every other day to see if it has improved! -

 

[Flicker]

I think it is given as a useful guide for an approximate time that walking can be tolerated. So a few minutes either way is not going to make that much difference, but the vet doesn't want them out for, say, 1/2 hour, but wants them to have longer than 2 minutes.
When my lad was on box rest, for the first weekend, I was literally only allowed to walk him gently round the barn twice a day to just allow him to move a bit (so vet said '2 minutes walk at the most'), then I could build him up to 5, then 10 and finally 20 minutes in hand walking as he got better. These times gave me an idea of how much activity he should be given.

 

[Flicker]

Also, meant to say - I suppose grazing in hand is ok as they are not moving much more than they would do in the stable.
However, if my vet said 'box rest with 10 minutes walking in hand' I would never, never trot up without discussing it in detail with the vet first!