# Retain foetus deliver kits later?



## debjane (Feb 23, 2013)

Not quite sure where to post this.. 

Someone elsewhere said this..
'They (rabbits) can retain foetus in one of the horns until hormone changes in the body cause them to grow. Not common but not impossible. Well documented'

Really? And in this particular instance 11 weeks later?
Does anyone know of rabbits or any mammals doing this? I would love to see any papers about this?

:-/


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## OakRidgeRabbits (Feb 23, 2013)

What exactly is your question? Can a kit be retained and then expelled 11 weeks later, alive and well? No, not that I'm aware of.

But they can be retained and expelled weeks later, stillborn. They can also be retained permanently, which I've heard usually makes the doe infertile and occasionally can kill them. That's about all I know of it, from the experiences of other breeders. I don't know of any legitimate studies or papers posted online. Rabbits aren't as heavily researched some other domestic pets/livestock, so a lot of what we know is just through the experience of others.


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## debjane (Feb 23, 2013)

My question is... is there documentation to back up live litters being born many weeks after being conceived. That is to say not the usual gestation period but weeks after that, because a doe 'due to hormones' has retained the embryos and then they have grown much later at a more favourable time? 
I think I have heard in fish/reptiles or something (?) doing this or similar but never in mammals, but was awaiting to see if any one knew of studies/reports to the contrary. 
I feel pretty certain this not accurate and am annoyed as it is information that has been given out incorrectly. 
I'm fully aware of retained, still/late litters etc. Thanks.


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## missyscove (Feb 23, 2013)

There are some species that store sperm and can fertilize an egg much later, but to my knowledge this does not occur in rabbits.


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## woahlookitsme (Feb 23, 2013)

I haven't ever heard of it in 4 years of showing and breeding rabbits. General rabbit gestation can range from 28-35 days. The most they will do is a couple of days over and the kits will come out with hair already. If it is a couple of weeks the kits would be dead and the mom would be very sick


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## OakRidgeRabbits (Feb 23, 2013)

debjane said:


> My question is... is there documentation to back up live litters being born many weeks after being conceived.



No, I don't know this to be true.

Most litters are kindled 31 days after the doe is bred. At that time, the kits are blind and have no fur. However, it occasionally (very, very rarely) happens that someone has a live litter born days after that - sometimes as late as Day 35 or 36. I haven't had this happen, but those people have said the kits are born slightly larger, more developed, as if they've been growing normally and have a little bit of fur, just like they would if they were born on time.

Because of that, I don't think it's possible that a litter would just pause, stop growing, and be born weeks later. I've had rabbits for over 12 years and haven't heard of any evidence to the contrary.


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## debjane (Feb 23, 2013)

No I haven't heard of it either and I've been breeding over 40 years! Just wondered if any one had!


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## LakeCondo (Feb 23, 2013)

I looked up delayed gestation on wikipedia & found out that mammals in the bear & weasel [plus some in the deer] families have delayed implantation of embryos so that babies can be born at the right time of year for the species. But obviously this doesn't apply to rabbits.


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## debjane (Feb 24, 2013)

Once I found the correct name (thanks to LakeCondo) there are some articles out there - search Embryonic diapause. I added rabbits to that and am now doing some reading..


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## RoyalLions18 (Feb 25, 2013)

I had a doe have her baby on day 36 baby was very big and had a full body of hair. Baby died coming out because he was just to big. So i think it would be impossible for a doe to go weeks and have a life baby, they grow to fast.


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## debjane (Mar 12, 2013)

I did find some reference to rabbits but none of the topics I read said by how long it could be delayed before implanting for the fertilised egg to still be viable.


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## Imbrium (Mar 12, 2013)

debjane said:


> Not quite sure where to post this..
> 
> Someone elsewhere said this..
> 'They (rabbits) can retain foetus in one of the horns until hormone changes in the body cause them to grow. Not common but not impossible. Well documented'
> ...





debjane said:


> Once I found the correct name (thanks to LakeCondo) there are some articles out there - search Embryonic diapause. I added rabbits to that and am now doing some reading..



it can also be referred to as delayed implementation or embryonic stasis (which are actually two different things and there's no way to know which one is going on). sugar gliders (and from what I've read, most marsupials) are actually capable of this - the longest anyone has known a sugar glider to hold embryos is, I believe, 11 months! 

overview of sugar glider pregnancy:
~ female is "pregnant" for 16 days
~ at that point, the joey(s) are about the size of a grain of rice. they exit through the female's vagina and she licks a trail from there to the entrance of her pouch for them to follow. the joey(s) then go into her pouch where they latch onto a nipple. if anything causes them to unlatch prematurely, they'll die as they aren't able to open their jaw to reattach.
~ mom has four nipples, meaning she can carry two sets of joeys at once and she actually custom makes different milks for different stages of development!
~ joeys stay in mom's pouch for approximately 72 days, after which they detach from the nipple they were clinging to (but still stick their heads back in to nurse). their OOP (out-of-pouch) date is considered their birth date.

we don't know if it's that the egg is fertilized but not implanted or if the embryo actually grows for the 16 days a glider is normally pregnant but is then "frozen" at that stage of development indefinitely rather than being released so that it can crawl up to the mother's pouch... but gliders can definitely hold onto an embryo or two for a crazy long time.

that said, I'm *really* not buying that it's possible for this to happen in rabbits.


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