Linda Ryan,

We also decalcify whole mouse paws, because the investigator wants to look
at the joints.  We use Cal-Rite from Richard Allan.  This contains formic
acid and formaldehyde.  We've had really good success with the front paws
(which are smaller than the rear paws), and the knees.
 
We decalcify the front paws for 24 hrs, with 3-4 changes of the Cal-Rite
and we also  put them on a rotator.  We leave the knees on for  approx.
16-24 hrs, depending on what fits best with our work schedule.  We also
change the solution 2-3 times and keep them on the rotator.

We haven't perfected the time point with the rear paws yet, but we are
putting them in Cal-Rite for 48 hrs, on a rotator, with 3-4 changes of
solution per day.  They are decalcified well, but tend to fall apart on the
water bath.  It helps to pick them up really quick.  We also use coated or
charged slides for paws and bone.  Sometimes the rear paws turn out really
well, and other times they don't.  We always get really good results with
the front paws and knees.

I have a procedure that helps you determine the endpoint of decalcifying
procedures using ammonium oxalate, but it takes about 30 minutes to get
results.

I hope this helps you some.  If you have any further questions, please feel
free to email me.

Rita Angel, HT (ASCP)