The Dangers of Leaving Dogs Outside Alone
Dogs should never be left outside unattended, for many reasons.  Toy
dogs, especially, are in danger when outside alone.  Below are just a few
links to the many tragedies that can occur.  We have included the search
terms used so you can research it for yourself.  
THEFT:  An estimated two MILLION dogs are stolen from their owners each year, the
majority of them taken right from their yards.  Fences are no deterrent whatsoever
(search term "dog thefts"):

http://www.petfinder.com/dogs/lost-and-found-dogs/prevent-pet-theft/

http://moderndogmagazine.com/articles/dognapped-frightening-facts-pet-theft/147

http://www.akc.org/press_center/pet_theft.cfm

http://articles.baltimoresun.com/2013-05-02/news/bs-md-stolen-dogs-20130502_1_mor
e-dogs-south-baltimore-thefts
PREDATORS:  Coyotes, hawks and owls all pose serious threats to small dogs.  
They are in every state in the country, and they are in cities as well as suburbs.  Just
because you haven't seen them doesn't mean they aren't there:

BIRDS (search term "owl kills dog"):

http://birding.about.com/od/birdingbasics/a/Protect-Pets-From-Birds-Of-Prey.htm

http://news.google.com/newspapers?nid=2457&dat=19950106&id=86lJAAAAIBAJ&sjid=WA4NAAAAIBAJ&pg=6121,977375
COYOTES (search term "coyote kills dog"):

http://wtvr.com/2013/10/09/coyote-kills-chesterfield-familys-dog/

https://www.dailyherald.com/article/20131212/news/712129839/
Think coyotes aren't a threat because you have a 6 foot fence?  Think again!
(search term "can a coyote jump a 6 foot fence"):

http://blog.adoptapet.com/keep-your-pets-safe-from-coyotes/
All of these links are reputable news sites or well-known dog sites.  Please take the
threat seriously or your little one may pay the price.  For these reasons, we cannot
adopt to homes with dog doors.