Best second dog?? Suggestions?

  I have a year and a half old maltipoo and she generally is home alone. I really want to get a second dog preferably one medium or large sized. Any suggestions?
Just go for opposite sex, different breed, size and age but try to match their energy. This will help them not have issues. Then go to the local shelter looking for the right dog. Once you find what you think it is, find out what it's dominant breed is come home without adopting yet. Do your homework on the breed and see if it is a match to your lifestyle, space and exercise regime. Than go back and adopt if it's a fit.
Shelties are usually good inside breeds and they are easy to train.
chow

papillon

whatever you want to train