Check out the Model railroad section of your LHS. O gage is 1/43rd scale which may work for you.
http://www.oakridgehobbies.com/o_scale/o_woodlandscenic_figures.html
http://www.oakridgehobbies.com/o_scale/o_41-42.html
Otherwise there are a couple of sets of which include dogs with them.
http://www.quarter-kit.com/catalogus/itemEng-kshg31.html
http://www.quarter-kit.com/catalogus/itemEng-dmm48008.html