While the thought of dog mess based tanning is disturbing, tanning
hides has traditionally been a very messy operation.  Check out an
ancient method for hide preparations at
http://www.braintan.com/articles/furs/miller1.html

My wife's cousin in Montana makes reproduction Native American pieces
using this exact method.

The other methods are considerably more toxic.  I live in Fort Worth,
Texas, and they have just cleaned up a site here that was an abandoned
tannery.  The site was full of extremely toxic wastes, including
hexavalent chromium of Erin Brockovich fame, that was just left in
rusting and splitting barrels for some poor fool to find years later.

Ted Konetski