A friend of mine has a broodmare just over 375 days.  Vet looked at her and said all seems fine.  Has anyone else had one go well over 370 days?

Bump

I'd bet money the foal will be born dysmature.  It is not normal for them to go that long.  

Worked at a breeding farm in OK.  We had a young appy mare go 392.  Baby was born small but completely fine.  AI so breeding dates were confirmed and not a mistake...  She was on foal watch forever... Definitely not the norm, but a few mares would hang on until that 370 or so mark.

Horses can go 10 1/2 to 12 months.  She should be popping quick.

I had a mare go 13 months and had a healthy lg. colt. My inlaws had 2 Arabian mares that would go 13 months everyyear. Not un common.

I've had 3 mares go 365-372 days. All three mares were Biankus bred on the top. (That shouldn't make any difference. Just strange.) The babies were all normal size and development. 

There's someone that has a mare right now bred to my stud.  She was last covered live on 3-25-19 then shipped home. She's not foaled yet.  Tick toc.

I and one go just a few days from 14 months, it had been planned to intervene in the next week. Maiden mare, foal was still born, very small but developed normal, we assume foal died during labor because mare looked to have been in labor a while when I found her and then it took over an hr to get a vet to me. We think mare had trouble with placenta attachment or something because foal was so small and I kept saying are we sure this mare is bred?? Because she never gained a lot of weight to look pregnant. I’ve heard of 2 others going this long and they did fine.

Just an update. The mare I mentioned above that was last bred on 3-25-19 just foaled last night. 389 days.  Normal, healthy baby. 

Wow that's a long time! Glad momma and baby are fine, just needed to cook a little longer I guess

We currently have a maiden mare at 367. She's just starting to get some edema in her bag, but no milk yet. She's a bigger framed mare and she didn't really look heavily pregnant until recently. She's in foal to Jesses Topaz, so we are hoping all is well (is definitely still in foal, has been palpated recently and can see the foal moving around). My husband has seen mares go over a year multiple times with no issues, some just have more room to keep them cooking for longer until they reach capacity, their bodies get stressed, hormones change and it's time to foal!

Update: the maiden mare foaled that afternoon (367 days) and had a beautiful, healthy stud colt!

My 7 year old was in utero 372 days. A I so no miscalculations. Born perfectly normal in every way.