OK - well, you know about German Shepherds and Rottweilers, so Max is out of the way.

Shelties are from the Shetland Islands, where they herded sheep. It was necessary for them to develop a good, loud bark to be heard above the sounds of the wind and waves while they were watching the sheep.

Chihuahuas are descendants of the Techichi dog from Mexico. It was a sacred, mute dog which was held in such high esteem that the Tolcechs (sp?) thought that they had to be buried with one to increase their chances of going to heaven.