hind end problem

[TddWil@aol.com]

To make a long story short, this horse was abandoned by its owner and my 
friend is stuck trying to care for it. He moves very funny behind. If he has 
to rock back on his hocks to turn around he almost falls down. He trots very 
uncoordinated, doesn't seem to bend the back legs much and they look weak 
during the weight bearing phase. At a canter he seems to hop up and down in 
back - alot. He is also impossible to keep weight on, whether or not this is 
connected to the rear end thing I don't know. He has been wormed and his 
teeth seem in good order. EPM? Injury? Spine out of alignment? Help! Oh, he 
is about 6 and arab. 

                                                 Shelly in DE