Hello,
I’m new here and was turned to this site by my animation and gaming teacher. We are doing basic character rigs for our final projects. I’ve been having a bit of trouble with my cat’s front legs. Until now I’ve been trying to go off of a giraffe rig tutorial from the Mastering Autodesk ® 2011 book. Since the joints are a bit different, it’s not really working. The back legs are fine, it’s just the front ones that don’t work.
I was hoping someone here could help me understand what I’m doing wrong. 
The constraints of the front joints don’t allow the elbows to collapse, they just keep moving down. Is this an IK RPsolver issue? Should the IK be configured differently?
This is what the front legs are doing when I try to move the rig down:
This is what it really should not be doing.
In this one, the joint still needs to be able to move like this, but stop moving down at about this point, allowing the joints higher up to collapse down.