I was amused list the various breeds and types of creatures has hooves, this is the result in the wiki ^^
http://e621.net/wiki/show?title=hooves
I also completed the purification tags on research "dragon" (3040 pictures :P)(pokemon and digimon summers are ignored during this treatment)
Now, the tags "animal" "zoo" "quad" and "non-anthro" There are over.
The research dragon + feral only gives results on dragons quadrupeds non-anthro, with just two tags.
http://e621.net/post?tags=dragon+feral&commit=Search
There is still much work but I felt that starting with the dragons would be a good start :)
Updated