Untrained Dog or specific breeds of dogs like the Beagle, are very emotionally attached to their owners. So much so that they can howl the full time you are away, now imagine that you live in a condo with 6 other units and share a common space and all the dog does during the day is sing sad songs! 

If treated right away with most breeds that will not last long and with the continuous training and application your dog will learn to be ok without for hours at a time, you know because you need to work to buy them food :) 

Dogs are like children and they get attached you need to learn to control the level of attachment without compromising the love given