There are many theories about genetics, hormones, eggs, breeding times, re-absorption, high protein feed, age, blaming the buck, little competition for space and nutrients in the womb, and more as to what causes a doe to have a fetal giant, but whatever the cause, which you may never know, the results are simply one kit becomes far larger than a normal kit at birth and it seems that it can happen to any doe at any time. First timers and older does seem to be more susceptible, but some does have a tendency to have fetal giants during their breeding life periodically.
Kindling a fetal giant is particularly difficult and risky for the doe. She can experience trauma and internal bleeding. Some have even died during labor or a few days later. Although, some breeders practice re-breeding immediately after a doe loses a litter, in this case it might be prudent to give the doe a few weeks to fully recover before breeding her again.
Typically, the doe carrying a fetal giant will go pass her due date. She may kindle live or dead, normal kits and/or more developed kits having fur and/or undeveloped ones before or after birthing a fetal giant. I have read where a doe will kindle one or more and then nothing for several hours to two days or even more before passing the fetal giant. If a doe passes one or perhaps two normal or smaller sized kits, she probably is not done, because if there were only two, they would be on the larger side, but not necessarily fetal giants.
I warn you that pictures below of fetal giants are disturbing, because the strong contractions and size limitation of the birth canal not only results in the kit dying during birth but the kits have a crushed, elongated, and even twisted appearance. Fetal giants may be a bit more developed than kits usually are birth, such as having some fur already coming in.
One of my does kindled a normal sized kit and that was it. When I palpitated her, I felt a large mass in the birth canal and just knew it was a fetal giant. She finally birthed it two days later. Although my doe lived after passing this fetal giant, the only one we have had in seven years of breeding rabbits, she was pretty torn up from it. It was to be her last breeding as she was an old doe, so we culled her. Inside, she had three underdeveloped fetuses and blood in the urinary bladder.
The pictures above were posted on a message board about rabbits and I was given permission to post them here. Unfortunately, her doe died a day later.
I had not heard of a doe having two fetal giants in the same kindling and I thought that it would be unlikely, but not necessarily impossible. Soon after my own fetal giant experience, another came into my life through a member of a rabbit group on Facebook, who was in the process of assisting her doe in birth. The two below were from a dwarf breed, but whether that had anything to do with it is unlikely. Fetal giants can happen to any breed and size of rabbit. In this case, the doe seemed to be recuperating well a few days later.
