Equine related

[guntersmead]

if 'S from T H M translates as 'Straight from the Horses's mouth' ...what does 'To B T W H' translate as gor quiz purposes?

[douglas9401]

To back the winning horse?

[Old_Geezer]

beat the wife heartily
(but possibly only if she's part of the horsey set ?)

[rsvp]

I think it means 'to back the wrong horse'