It is possible that a mare could be slip a foal very early on and miss a cycle before coming back into heat at any age. Older mares have a higher chance to become infertile or less fertile. Each mare is different and so is each pregnancy. Have a good relationship with your vet, check via ultrasound to make sure she is pregnant or not (coming or not coming into heat isn't the most accurate method to determine pregnancy since some mares may start a false pregnancy and others may still have "heat cycles" while they are pregnant.
Thank you so much for answering my questions!
Has she previously been bred?
Personally, I'd be working with my vet on this.
Yes, she has been bred before (to the same stud I'm breeding her to this time), but it was a long time ago (her foal from that breeding is now seven years old).
Why did you not get her ultrasounded?
Did you even have a pre-breeding exam done on her to ensure that she is healthy at 19 to be bred?
I didn't get her ultrasounded because it's personal preference to do that, and I chose to not ultrasound. I've never known anyone personally to ultrasound a pregnant mare and every mare's pregnancy I've been around has turned out just fine without ultrasounding, so, in my opinion, it's not something that I feel like I 'absolutely have to do'. Now, if my mare or the stud in question threw twins in the past or something, I'd consider ultrasounding, but it's just not something I feel like I 'must do'. Personal preference and all.
As far as making sure she's healthy enough to be bred, I've spoken to both my vets and outlined her issues with arthritis (and the supplement she's on), her (now fixed due to a better feeding program) issues with keeping weight in winter, etc... and both were in agreement with each other that she'd be fine to breed this year.
You need to have her checked by a vet... Ideally she should be checked 14-16 days after breeding to check for twining.
This is, I am guessing, the same nieghbor who bred you mare to the wrong stud in the first place because he "forgot" right? I would be taking what he says with a grain of salt and dealing with a vet in regards to your mare and not the stud owner.
Please don't tell me what I 'need' to do. It's personal preference to have her ultrasounded by a vet and I chose not to and have already explained my reasoning. Twins are extremely rare, in any case, and I highly doubt she'd have twins anyway, since they are so rare.
And yes, this is the same neighbor and the same stud. For a few minutes, upon realizing she was in heat again, I debated rebreeding her with the other stud, but in the end I chose not to because I like Bear better and he better suits my mare. My neighbor may be older, but he's been a breeder for most of his life and, while he does tend to forget some things, I still trust him and respect him.