Young rabbits ears are drooping

Question
We are foster-caring for a mother rabbit and her four young bunnies.  They are approximately 4 weeks old, we think--eating regular food & not nursing anymore.  They have been in good health.  WE've had them about two weeks.

All five rabbits are "regular" breed--not lops, as far as we know.  All have had "normal" bunny ears--upright and extremely mobile.

Today we noticed one (a female) suddenly has droopy ears--like a lop.  This morning it seemed like they drooped but she could still raise them up and move them.  Tonight, they seem even droopier and she can't seem to raise them up anymore.

Is this anything to worry about?

Answer
Dear Luann,

The most likely explanation is that she has inherited copies of recessive genes for lopped ears that were not expressed in either parent.  The parents were probably "carriers" of the lop alleles, but since wild type (up eared) genes are dominant, they had up ears.

Lop bunnies usually start to drop their ears at about the age you describe, though some wait until 6-8 weeks.  

In some cases, ears can droop due to infection or infestation with ear mites.  If you suspect this is the case, bring the wee bun to a good rabbit vet for a good look into the ears.  If they're clean, she's probably a lop!

You can find a good vet here:

www.rabbit.org/vets

Please also read:

www.bio.miami.edu/hare/breeding.html

Dana