I second this. Get a dog. You never know who you'll meet when spending time with that guy, you two might even find yourselves a new family.
Do it, OP.
Do it, OP.
Pets can go both ways. I've been in depressed states where my pets were the only thing keeping me going. I didn't want to live any more, but who would take care of my pets? I had to force myself to function so that the pets didn't starve or live in their own feces. That constant, gentle kick in the ass was what I needed a lot of the time.
Like you say, it can unfortunately cut the other way as well. Dogs are an especially high-risk proposition because they are a big time and money commitment, and if a person is feeling overwhelmed already... that could be trouble.
Possible compromise: volunteer at an animal shelter?
When you're in a low, low, low place you might not care about yourself enough to get out of bed. Or the world might be too painful. Or both things, plus one hundred other things.
But you will not stay in bed when you have that dog depending on you. You will not let the dog go hungry nor unwalked.
That said, a dog is not a magic pill! A dog is a huge commitment, nearly on the level of having a child, and if feeling overwhelmed is one of the causes of your depression, a dog could exacerbate that.