My clinic does not induce unless medically necessary. This has been changed with in the last 2 years. To much risk to induction.I'm guessing within 6 days post due date as doctors are rarely right. Every "mare's" cycle is different and they go by a perfect 28-day cycle(Who is normal?) Unless you were early with your first naturally or they push you to induce (which they almost always do). What I wouldn't have given not to have been induced both times lol.
Why don't we induce mares? Because they are rarely ready when we are. Why do they induce women? Sometimes for a good reason. Sometimes it's just out of convenience.
That said I know the exact day I conceived, and this "mare" doesnt have a 28 day cycle. Thus I say my due date is 11/11 based on my cycle length which is only 2 days longer then there due date of 11/9.