Hi Jen,
I am so sorry to hear this.. I am, by no means, a rabbit expert but your rabbits might be suffering from a couple of different things. (and I'm taking a shot in the dark without knowing rabbit breeds, feed content, rabbitry set up etc) The one that jumps to mind is "Young Doe Syndrome". What I am telling you is also coming straight out of "Rabbit Production" by McNitt.
When the doe is 4 to 10 days after kindling (or longer) they just unexpectedly die. Enterotoxemia or Staphylococcal mastitis can cause this problem.
If it is enterotoxemia a postmorteum will show an inflamed cecum. If it is the mastitis the toxins from the bacteria invade the blood and eventually kill the doe. The common denominator between both diseases is the doe goes off her food. And the enterotoxemia kills within 12 to 24 hours. The mastitis is slower.
Good news is both are treatable if caught in time.
Hope this helps or at least gives you a starting point on clues to look for. There are several other diseases that might be causing the deaths but these are the two that come to mind first. And you might have different things happening to each doe.
And not trying to be offensive, how much does your vet know about rabbits? Did they specialize in rabbit studies. I am really lucky because our veterinarian specializes in rabbits. They are worth their weight in gold.
Good luck.
Carolyn
