Record-breaking Gestations for Minis?

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Dontworrybeappy

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Abbie (whom some of you may remember was born at 292 days gestation - with a single hand-breeding date as guide) is now at 369 days along in her 2nd pregnancy (her first went about 330 days). She is a young mare, healthy, no signs of distress (except in her owner!
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Live foal palpated by vet at 343 days along. Hand bred by stallion owner and delivered here 2 days later, we have had no stallion escapes here, and no stallion near the mare's corral at all.

How long have you had a MINI mare go.... and still have a healthy, live foal?

I've read the following, but I'm going to assume these are mainly regular (large) horse breeds and not minis!

"Here are some important facts to consider about gestational lengths:

  • Foals born prior to 300 days are unlikely to be viable.
    Their lungs are not fully developed and they will not be able to breath.
    Unlike similar premature situations with humans, the use of a surfactant in the foal to assist with development and breathing has not proven succesful.
  • Note that this is referencing a normal, healthy pregnancy. Mares that manage to support a pregnancy threatened by something such as placentitis to term may have shorter-than-"normal" pregnancy duration, and yet still present a viable foal. It is unusual that the gestational period will be lower than 300 days in this case, but it can happen. This is thought to be as a result of elevated cortisol levels - due to fetal stress - causing accelerated fetal development.

[*]It should be noted that considerably shorter Miniature Horse pregnancies (~280 days) have resulted in healthy foals.



[*]Foals born after 300 days but prior to 320 days are at risk of being born in a premature condition.

  • Premature foals will require neonatal intensive care;
  • The closer to 300 days the foaling, the more intensive the needed care will be;
  • Foals born from mares that suffered from infectious placentitis during pregnancy may be born between days 300 and 320 and yet not show prematurity as there is an accelerated developmental rate in utero with many of these foals;

[*]The average range of gestation is between 320 and 370 days.
  • 340 or 341 days are accepted as the most common foaling days, but they are not a "due date", merely an average of the average.

[*]Foaling days after 370 days of gestation are not uncommon and usually do not represent a problem.

  • The longest live foal delivery on record is 445 days!
  • Foals born after a prolonged gestation are often small in size as a result of a delayed uterine development period, and rarely present foaling problems as a result of "having grown too big".


Some other important points for consideration:

It should be noted that if the mare is displaying severe signs of discomfort, she should be evaluated by a veterinarian. "Severe signs of discomfort" are not represented by a mare looking miserable, but rather by colic-like symptoms or extreme depression (no interest in feed, turnout, other animals etc.).

Induction of foaling simply because it is convenient for the mare owner, manager or veterinarian and not because of the presence of a medical problem with the foal or mare should be a crime that carries a mandatory life sentence! Induction of foaling results in a higher-than-normal number of dystocias (presentation problems), premature foals, and premature placental separations ("red bag" deliveries) than are seen with regular presentations. Do not induce foaling except in the face of a very clearly defined medical need, and only under strict veterinary supervision.

It is also important to note that while mammary gland development may be indicative of impending foaling (note that "waxing" is not a reliable indicator across the board, and other methods of prediction such as the one described in the article available by clicking here should be used), an absence of mammary development when in concert with prolonged gestation may be indicative of a problem with endophyte-infected fescue toxicity, and immediate veterinary involvement should be sought, as drug therapy (Domperidone) and other protocols (removal of the animal from the endophyte source) can be used to reverse the symptoms. Just to confuse the issue however, some mares do not show mammary development prior to foaling, and yet have not been exposed to endophyte-infected fescue!

Horses are not humans! They have different needs, and while the gestational period for humans is quite closely defined, there is a wide range of "normal" for the equine! Consequently, if you are reading this as a result of being concerned about your mares pregnancy duration, while we certainly encourage you to consult with your veterinarian to be on the safe side, you are, in all probability, merely losing sleep and worrying for no reason!"
 
I am no help as the only two I have had go over 330 days were 1) a mare that went at 335 days and had an overly large foal that came with one hind foot forward and 2) a mare with iodine deficiency combined with nitrate poisoning--she went at around 340 days, which was way overdue for her (normally foaled at 300-315 days)--foal had congenital hypothyroidism and was born so weak she never got up, died within the hour.

I know people who have had mini mares go a full year or a little more and the foal was born healthy, with no difficulty for the mare. For myself--I want them to foal closer to 300 days than to 365 days, and if they get to 330 days without foaling--yes, I worry, a lot.

In big horses, 330-340 days was the norm. I had one mare foal right at 365 days, no problems, but the foal was very big and fat--he came out looking like he was almost a month old. So--the info above regarding a long gestation foal not being extra large is not always accurate. That same year a neighbor had a mare (QH) go a full 365 days--her foal was very large and the mare was fatally injured while delivering the foal.

They are all different and unfortunately there isn't a darn thing we can do except wait--and worry. Most likely your foal will be born healthy, but I know that you are still going to worry in the time between now and when it arrives.
 
Not "one size fits all" when it comes to gestation. I've had one mare that religiously foaled (history of 4 foals) at 300 to 305 days and babies were fully cooked. And another that ALWAYS foaled at 12 full months. Her babies were not abnormally large. However, this mare herself was a slow developer and did not lose her caps until almost 5 years old. Hmmmmm.....
 
One mare I bred usually foaled at 326 days. One time she foaled at 363 days - the foal was not particularly large, about 23" tall, but was very developed, like minimor's foal, he looked like he was one month old, very mature. He matured at 30.5"! so foal height was not an indication of mature height. The mare was experienced and had no trouble foaling, just popped him out. He was very smart, born, jumped up and went right to the udder without all that wandering and figuring out where it was, if you all know what I mean.

I know you are concerned, but if the foal is not ready to be born he is better off. Do you still see kicking, movement, etc? I looked at your camera feed, she looks relaxed and content.
 
Yes, honestly, if I didn't have confirmed breeding dates (as in, the mare was delivered back here within days after she went out of heat!) I wouldn't be so concerned. And Abbie is a mix of ready/not ready signals.... but she's also now 370 days since her last breeding date! My longest big mare gestation in the past 35 years of breeding was 372.... foal was fine but had a (temporary) kink in her tail from literally sitting on it, in diving position, for the last month!

I've been foaling out mini mares for the past 15 years, sometimes as many as 30 a year in my capacity as a mini mare midwife, and I think the longest we've had a mini go was 350. (Abbie herself was our shortest gestation at 292.... my vet says she's making up the time by cooking this one longer!)
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She was a mix of ready/not ready signs when she foaled her last foal at around 330....
 
I stopped breeding and foaling out mini mares after 20 years of it (miss it), 40 live foals and one aborted at 9 months because of the cord wrapped around the foal. You have sooo much experience I am sure Abbie is in the best of hands! These mares like to do their own thing, don't they. I had a few mares foal with no bag to speak of and milk came right in after foaling and others dripping milk, so I know they can be little rascals with their signs or lack of! My shortest gestation was 302 days and it was a healthy and viable foal after I had the vet tube it with a good dose of colostrum and milk. My average was 323 days. I bet you can relate some interesting stories of sneaky mares. Good luck with Abbie, by the way, your little colt is so cute in the other stall.
 
here's a friend holding Abbie on the day she was born (at 292 days along!) She was my earliest live foal and was born out in the turnout with a group of mares, I found her at breakfast... obviously I wasn't expecting a foal at 292 days and her dam hadn't even had a bag! We lucked out and all was well, just needed a bag of plasma to fix her low IgG levels - either mom didn't have colostrum, or, more likely, Abbie's tummy wasn't developed enough to absorb any antibodies!

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and here she is from yesterday, 370 days along.


Yeah, I have a lot of stories - good/bad, silly/fun/serious... mostly we've done well and if a foal CAN be saved, we've managed to save them... my vet even tells people "Well, if it were at Karen's, it'd probably be OK...."
 

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