How do you figure out due dates?

I was told to just use 11 months plus 6 days. Anybody have other methods they could share?

I've been told several things....11 months and 11 days and just straight 11 months are the most common.

The thing I've learned is that each one of these blasted mares is different...we've had mares foal at 11 months to the day, 360 days, just short of 11 months and 11 months 11 days and everything in between...

The mares sort of set their own pattern...consistent buggers...
Double S Farm in TX has a foaling calc on their web page...its pretty handy for when you give vacs etc...Ronnie Stewart is amazing...he is a great guy to work with and he has some great stallions in the line up this year! (as always)
http://www.doublesfarm.com/calculator.htm

I've found that the due date just helps with my impatience. I've got some textbook foalers, and then i've got some that don't barely bag up, don't wax and what do you know, there's a foal in the stall. Last year I would have swore Trouble wasn't close to foaling when i turned her out in the morning, but by lunch, there was a foal laying beside her.
I make sure my foaling kit is handy at least 2 weeks before I think they ought to be due.

Dream horse has a program on the web site you just pop in the last date bred and it will give you the dates..

340 days is full gestation. So, you can take 12 months and minus 26 days if you want to strain your brain.. Or, just go to DH and pop in the dates.. And, knowing your mares and how long they carry them helps. I have one that foals early every time. She foals at 320. The nice thing about AI is I know exactly what day they ovulate..

I just do the 11 months 10 days. But as you know their gonna have them when they have them.

I do the - 11 months since last breeding date. But yes, mares are usually fairly consistant in their gestations, of course depending on other factors...

I have one mare who won't be stalled... it stresses her too much, but is fine to be in there with her new born, just wont put up with it any other time.... But I've had 2 foals out of her, and can't seem to catch her. One morning I had her in with her 2 best buddies, and she was "overdue". I checked on her at 8am before I headed to work (no signs of impending birth other than what she had already been showing for 2-3 days) and asked my mom to check her at 8:30... and bam, foal at side. stinkin silly mares. Thankfully she births without issues.

then I have a mare who literally tells you when she is ready to foal, she will be "sucky" for 10 days prior to foaling, and on the tenth day follows you around and wont leave you're side... lol she must get nervous. She also drips on the last day and waxes on the second last day. Once she's dripping, she foals within the hour.

What i've made a point of doing for every mare and every foal is writing in a "log book" stating all the different factors to ensure I remeber, and have the best luck of being there for parturition. Also, its good for having on hand if your mare has issues to provide for the vet so he knows her "history". I record;

beg-end breeding dates, each gestation length (in days), any complications (from actual foaling complications, to retained placenta, to neonatal issues), birthing signs, mood changes close to parturition, pregnancy complications, and I will also record the time for each foaling... and compare... if it begins taking longer than an indefinate "normal foaling"... I will either help myself, or request guidance from my vet.

The DH is way less brain strain.. And, true about them foaling when they are ready just like humans.. Knowing your mares is most important. Pasture breeding does leave a lot of guess work.. Much of the breeding that is done that way happens at night when no one is looking.. I would hope that everyone is ultra sounding for twins that is doing pasture and live cover..

Keeping a log is very helpful.

I hand breed all mine, so I have a better idea than if I pasture bred.
The ultrasound that Wade's dad bought back when they had PMU doesn't show the foals on a screen, just does some measurements. Can also be used for measuring back fat on cattle for cying out loud. But try to tell them that it isn't good enough for my horses. So I usually take my mares to the vets office by myself and get it done. This year I snuck mares over when Tony the Welsh was getting x-rays and treatment after getting kicked.