Well I have had the stallion for 2 yrs before i sold him because she wasn't getting pregnant and I knew 20yrs old was just too old, she is perfectly healthy and the vet said she seemed healthy enough to deal with a pregnancy and it would be alright. So I tried for 2 yrs then, even though the vet said it was fine to breed her in her early 20's, I decided no, enough was enough. So it was either neuter Ity Bity, the stallion, or sell him and because I had financial tightness I sold him.
She has done this udder development last year and the vet did come out and said it was due to the lush grass playing with her hormones. All she said was keep her off the grass until the udders go away then limit her grass. I have been doing just that and at first her udder went down but when I was away, it grew larger. My mother was watching over her and assured me she had no access to grass at all, just hay and water.
I'll try to get images today to show her belly and udder but because of her age someone mentioned horse menopause or a false pregnancy but if it's either, what do you do to stop it? What do horses do when they are old? Do they stop coming in heat? If so, would that trigger a false pregnancy? She has had one other foal, back when she was around 5yrs old. The pregnancy and labor went fine but she did abandon the foal, but she is also blind in one eye and I think the old owners were too hands on and dryed the baby off before Missy got a chance to see the baby.
She is currently stretched out in the sun, obviously very worried about her health. haha