The expression, to lead a dog's life, describes a person who has an unhappy existence.

VOA: special.2010.05.30

They say that to be successful, a person has to work like a dog.

VOA: special.2010.05.30

President Obama has promised his two daughters a dog.

VOA: special.2009.02.23

"But then it became so affecting and really important as far as recognizing a wounded veteran like Bill Campbell and the dog that really has saved him and the inmate that trained the dog.

VOA: standard.2010.05.18