Not many people here have experience with baby rabbits, but it could have been a runt that just didn’t develop quickly enough. Maybe organs didn’t fully develop to sustain life.

I’m sorry for your lost and wish the rest of your babies good health.

If it was the product of two dwarf breeds breeding, and they were both true dwarf, it could likely have been a peanut and peanuts usually don’t live past 1-2 weeks old.

That’s a true dwarf, so it was peanut, which happens when it gets two copies of the dwarf gene.

I did a cursory search, and it seems there are distinct differences, mainly in the development of the body.

Runts are simply smaller versions of a regular baby bunny.
Peanuts may have underdeveloped features. Their head may be shaped differently, and a few online posters of random forums mention they may not have developed hindquarters (may not be able to move the legs as well, lose balance, etc.). People also mention smaller ears to larger head. Based on your photos, it does seem like the baby who has passed had a more drastic ratio b/n head and ear size.

So maybe a peanut. Again, I’m not experienced.

Also, if you’re not a breeder, will you be keeping the litter after they turn 8 weeks old, or will you be sending them to a rescue for adoption? There are items to consider if you’re hanging onto them, such as separating them for their safety so they do not turn against each other when hormones hit.

Make sure the baby is definitely at least 8 weeks old before the people take them. If they’re taking both, make sure they know to separate them because they won’t get alog forever because they’re siblings!

Keep doing your research and best wishes to you and your buns!

I would post your information and pictures to http://www.rabbitsonline.net/ instead. Users there are much more knowledegeable about these matters.

I am sorry about your baby bunnies. The first one looks like it was a peanut, the head is enlarged with tiny ears and the hind end is less developed, peanuts always die.

In the picture 3 hours before the 2nd kit died, both of them look quite dehydrated like they haven’t been getting mild. See how wrinkled the skin is? This is a sign that it’s been too long since their last feed. After they have eaten they shouldn’t be very wrinkly at all and their bellies will be big and round like ping pong balls. If the mum isn’t feeding the kits you will either have to supplement feeding, or hold the mother upright on your lap and hold a kit up to her teats from underneath so that it can feed. Make sure the babies are always up the right way when feeding, never tilted too far back or upside down as it is dangerous for them to feed that way.

Sorry to hear about the babies. A lot of first-time bunny moms don’t take care of their babies because they don’t quite know what to do either.

Some just don’t have the instinct. It’s not uncommon with first time does.