Note: I have a vet appt scheduled in a couple weeks and we’ll find out for sure then!
In the meantime, some fun speculation. Three year old mare I acquired in late February. She was underweight then and quickly gained through the spring. And continues to gain, and gain, and gain 
Recently, her teats have gotten a bit fuller and I can express milky liquid. As a 3yo maiden she had teeny tiny teats you could barely see. They’re still small now, but definitely bigger. Her vulva appears a bit puffy, although not lax.
The farm I bought her from does have a stallion (a tiny pony) although I was told she wasn’t exposed. Her home before that was her TB breeder, also with stallions on premises. She left the breeder’s farm in October.
I put her on regumate when she arrived at my farm because she developed an unhealthy attachment to another mare. So no cycles.
Any breeding would have been accidental I’m sure.
So who wants to take bets?
In March:
In July:
This week:
Teats:
