We have 2 Chihuahua... Smooth coats
When you think of them as skinny, shivering taco bell dogs,
you are thinking of the teacup variety.
The Standard Chihuahua is very smart, easy to housebreak and
Crate train.
They have incredible hearing and will bark to alert you of anything
unusual in the house.
Smooth coat variety is easy to keep clean and shed very little.
The standard breed is sturdy and can even play tug of war with toys.
Ours stay in their small kennels in the foyer for several hours while we are away, and even all day occasionally. No accidents.
The only negative is the tone of the bark, as with other small dogs
it is described as yappy.
But believe me, when they bark, they have heard something not right or you are having company they don't know..
My second choice would be a Jack Russell terrier but they have been overbred thanks to the Frasier TV show