Ethics - When buying a mare listed for breeding at sale. But choose to race her

I assume there is no clause preventing the new owner for racing a mare once they take ownership.

My Question is.

What happens if horse breaksdown in race from known problem?

I also feel the previous owners can rather send the horse to a farm if they are that worried for the horses future.

My opinion if marked for breeding should on a sales shuld not be allowed to race without special VET clearance before each future race until retirement.