question on twins
Moderators: Roguelet, hpkingjr, WaveMaster
My vet told me that twins are caused by the mare herself, ie: a genetic pre-disposition to releasing two follicles or a follicle that divides (fraternal vs maternal twins). In other words, a mare that shows/produces twins once will likely show/produce them again. I passed on an otherwise nice mare recently because of her history of twinning and the resulting projected vet bills.
The reason for the filly being sterile in a colt/filly pair is that the male develops the sex characteristics weeks before the filly, so there is too much testosterone for her to produce ovaries correctly (more like she has internal testes). I believe there is a better explination in the book "Blessed are the Foals" however, I loaned my copy out and it never returned. 
Thoroughbreds have the highest percentage of twin pregnancy which is probably from all the years of selective and in-breeding.
Thoroughbreds have the highest percentage of twin pregnancy which is probably from all the years of selective and in-breeding.
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sulphurfire
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This is a curiousity question in regards to twins/possible twins. I saw a mare get bred then when she came out of heat after having a full heat cycle they induced heat and bred her again(this was end of breeding season and she had been open 2 years, 10 year old mare). Palpation showed she was bred two months later. She foaled two foals, colt (big foal) and an underdevoloped filly. Neither foal made it.Is it possible that she was actually bred twice, as there was not enough time in between naturla heat and induced heat to determine pregnancy?
Oh gosh... thinking back to High School Biology and I had one teacher that was SO fascinated by genetics we spent an entire year on this...
There have probably been many advances in understanding twins since I learned about this but I think this is very much dependent upon how the "twin" is formed.
In fraternal twins, the mare releases two entirely separate follicles, each gets fertilized and attaches somehow to the uterus, and two entirely separate animals are created. The DNA they share is that of true siblings, as if they were born in different years with the same parents, and they can be of a different sex.
In maternal twins, the mare releases one egg which is fertilized once, and later divides. This creates identical twins. They share identical DNA, 100%, are the same sex, etc. It is also possible, however, in maternal twins, for the mare's one egg to be invaded by two sperm causing the egg to divide. If they were an X and a Y, this might result in a female offspring that was studdish/sterile, because of the presence of ANY Y chromosomes in the female. Note that males always have X chromosomes anyway...These offspring would share at least 75% of their DNA. These twins are usually physically extremely alike, but not identical.
There have probably been many advances in understanding twins since I learned about this but I think this is very much dependent upon how the "twin" is formed.
In fraternal twins, the mare releases two entirely separate follicles, each gets fertilized and attaches somehow to the uterus, and two entirely separate animals are created. The DNA they share is that of true siblings, as if they were born in different years with the same parents, and they can be of a different sex.
In maternal twins, the mare releases one egg which is fertilized once, and later divides. This creates identical twins. They share identical DNA, 100%, are the same sex, etc. It is also possible, however, in maternal twins, for the mare's one egg to be invaded by two sperm causing the egg to divide. If they were an X and a Y, this might result in a female offspring that was studdish/sterile, because of the presence of ANY Y chromosomes in the female. Note that males always have X chromosomes anyway...These offspring would share at least 75% of their DNA. These twins are usually physically extremely alike, but not identical.
Here's a bizzare one - I met a gal who had purchased a TB mare that was represented to be in foal to a TB stallion. She was well along in her pregnancy, and looked every bit of 9 months along. She ended up foaling a little early - but to the horror of the owners she delivered a paint foal. Then, a few minutes later, another plain bay foal followed.
Apparantely, the mare was living in the pasture with a TB stud. She somehow got into the other pasture with the paint stud. She was covered by each stallion on her heat cycle - each fertilizing a separate egg. So, she delivered twins that were 1/2 siblings. Both foals ended up dying, so getting a TB registered that had a paint as a twin was a moot point.
Apparantely, the mare was living in the pasture with a TB stud. She somehow got into the other pasture with the paint stud. She was covered by each stallion on her heat cycle - each fertilizing a separate egg. So, she delivered twins that were 1/2 siblings. Both foals ended up dying, so getting a TB registered that had a paint as a twin was a moot point.
hi guys
After what appears to be a "normal" birth...and the placenta has passed...the foaling-man/woman may lay-out the placenta to make sure it's all been passed.
Often the placenta is then placed in a bucket (or whatever) to be discarded.
But closer inspection of the placenta may expose a mini-twin that never got past the very early stages. Many may not look for it...but I suggest it may happen more often than you might expect.
Respectfully
After what appears to be a "normal" birth...and the placenta has passed...the foaling-man/woman may lay-out the placenta to make sure it's all been passed.
Often the placenta is then placed in a bucket (or whatever) to be discarded.
But closer inspection of the placenta may expose a mini-twin that never got past the very early stages. Many may not look for it...but I suggest it may happen more often than you might expect.
Respectfully
Hi folks went and seen my mare today she is big but not as big as I thought she would be (since maybe holding twins) but is fine and healthy and was even lovy dovy. Will have the vet check her in a few more weeks she was on a april first cover. she was checked a few months ago and the vet thought she still had two foals then. I'm hoping they are all wrong and she gives us just one healthy one. thanks for info.
onalimb
FOS Out of 8 foals born here, I have had 3 of those little sacs show up. I even have one on video tape with me dissecting it and a friend watching making grossed-out noises. 
All of those mares had been checked at 15, 21 and 30 days with no twins being seen.
Also as an aside, every foaling on this farm has produced a hippomanes (the blob of liver-like substance) which as far as I know no one has found its exact purpose.
All of those mares had been checked at 15, 21 and 30 days with no twins being seen.
Also as an aside, every foaling on this farm has produced a hippomanes (the blob of liver-like substance) which as far as I know no one has found its exact purpose.
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Elusive City
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The man I bought my mare from had a vet bill saying she was pinched. When I called for her vet records it said he was unable to pinch too close. When I recived her at my farm she was 4 monthes along which left me with no options but to wait it out. I had her checked by a vet with ultra sound at 6 month, he could only see and feel one but it was up high and he said it should have droped down below pelvic, so he was guessing there was another foal allready down low. but of course no one knows for sure. she is a mr p line mare and she is 16.3 and built like a tank. I have her at a breeding/ foaling facility till she foals but I can't hardly stand it.
onalimb
I wonder if there's any truth to a mare having a predisposition to twinning. We have a mare who we bred in 2003, she took on one cover... twins. We pinched one and she ended up resorbing the other. So, we bred her again. Again she took on the first cover... twins again. Again we pinched, and this time the other twin survived and went full-term. We joke about this filly being one of four that we could've had.
On a side note, some of you remember we had a mare last year who tore badly at foaling... complete recto-vaginal tear. You guessed it... this "one in four" filly is the one that tore her mom. We had her repaired, most of it held, but the mare's back at Purdue right now getting the end portion re-repaired (is that a word?)
The part that didn't hold was very small, so it's looking really good for a 2005 breeding.
On a side note, some of you remember we had a mare last year who tore badly at foaling... complete recto-vaginal tear. You guessed it... this "one in four" filly is the one that tore her mom. We had her repaired, most of it held, but the mare's back at Purdue right now getting the end portion re-repaired (is that a word?)
The part that didn't hold was very small, so it's looking really good for a 2005 breeding.-
acharmer
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Mahubah wrote:NYBreeder wrote:If you have a male/female set the filly is almost always sterile and can act very studdish.
Interesting; I didn't know this was the case in horses, although I've seen this reported for cattle, where the female twin of such a pair is referred to as a "freemartin." Haven't the slightest idea where that term came from.
according to ENCARTA..
sterile female calf: a sterile female twin born with a male calf
[Late 17th century. Origin uncertain: perhaps from free + Irish mart “cow.”]
hi Roguelet
Have you considered that maybe the stallion you bred your mare to...not so much the mares proclivity toward twinning...was responsible for the multiple twinnings?
I suggest that some stallions produce semen that is viable for quite extended periods of time...say 72 to 96 hours (or even longer).
Conversely some stallions (such as Nureyev was) were viable for merely a couple of hours (more or less).
I suggest that if your mare ovulates and conceives off a cover...then ovulates again (yet another follicle) while the semen is still viable...voila...possible twins.
When selecting a stallion for your mare...I suggest you consider discussing with the standing farm issues relating to the stallion's semen (and libido, for good measure). You might then share this info with your vet (or have your vet discuss it with the standing farm) so that this important information can be taken into account when booking...in hopes of accomplishing the best result.
Respectfully
Have you considered that maybe the stallion you bred your mare to...not so much the mares proclivity toward twinning...was responsible for the multiple twinnings?
I suggest that some stallions produce semen that is viable for quite extended periods of time...say 72 to 96 hours (or even longer).
Conversely some stallions (such as Nureyev was) were viable for merely a couple of hours (more or less).
I suggest that if your mare ovulates and conceives off a cover...then ovulates again (yet another follicle) while the semen is still viable...voila...possible twins.
When selecting a stallion for your mare...I suggest you consider discussing with the standing farm issues relating to the stallion's semen (and libido, for good measure). You might then share this info with your vet (or have your vet discuss it with the standing farm) so that this important information can be taken into account when booking...in hopes of accomplishing the best result.
Respectfully
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Intrinsic Worth
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Many farms breed twice for double follicles and the chances of twins is very high due to this. Also, many mares go through a cycle in the spring of having multiple small follicles which tends to lead to more twins. One vet thought that a mare had twins, when she actually had a cyst and an embryo. He pinched the embryo and left the cyst. This is why it is important to scan a mare and not just palp in the first 20 days of pregnancy. If he would have scanned the mare the second time, he would have noticed that the cyst hadn't grown and the embryo had
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