have you heard the expression 'raise a hare?'

[maryknmercer]

[wildwood]

In Welsh this is codi ysgyfarnog.

'Raising a hare' is making a hare raise (standup, hares don't sleep in holes/burrows) so one can hunt/chase it.

I believe it to mean that it is a bit like "flogging a dead horse" or "futile continuation of a discussion subject".

[BW11111]

In English(and in Portuguese) it means to raise, introduce, or prompt discussion about a controversial topic

[Maitchy]

"Raise a hare" is the same as "start a hare": move a conversation on to a new topic (need not be controversial, but is irrelevant to whatever was being discussed until then; a "red herring" - or simply something more preferred to talk about).