>Yes I have horses and you can only feed linseed whole boiled (4hrs or so -
>goes really gluggy) or ground linseed is OK. Great for their coats, and
puts
>weight on them. Cant say I ever knew about any toxic cyanide. Just know you
>have to boil it or they can get sick. Although why would ground linseed be
>OK unless its been treated (say heated) before being ground.
>

Lin seed when rehydrated produce an abundant mucilage around the seed ( kind
of transparant jelly) horses being easely subject to colic ( when fed
unaturally) that might be the reason why it is not good to. give whole seed
to horses who will necessarelly swallow  a lot of them whole and will not be
able to assimilate them   once grounded it will be  fine .
From experience , eating rehydrated flax seed it  is almost impossible to
chew properly ,it is too slippery.

jean-claude ( who raised horses free ranging in the moutains of pyrennees
and who didn't need to supplement his horses with lin seed or whatever.)