Ok, heres my 2 cents for whatever it might be worth..
My first dog ever came from the humane society..(My dad told me he was "allergic to dogs" even tho I found out later he had had one growing up 
Tara was such a sweetie..She was a bit neurotic, but hey..I was back then too 
When I got her from the humane society..She had kennel cough and skin problems..
Regular visits to the vet helped..
She taught me a lot about dogs..And because of her I found out I was a "dog person" 
She passed on a couple years back during the dog food recalls..
Just before she passed on (at 15 years of age) Sheila and Mac came into my life..
Sheila is the cream colored dog in my avatar..
She is an escape artist and devious as can be..When she came to me, I was in my back yard (hobbling around on a cane from a bad car accident) picking up trash..She was nipping at my trash bag and I could see she had recently had pups..
Mac is one of her pups..(he is the spotted dog in my avatar)
We didn't have a fence then..And because she was so good at escaping..We got her fixed as soon as possible..
Mac..I never did get fixed..
He is the sweetest gentlest dog I have ever known..
And smart too..If I wasn't so attached to him..He would be a good candidate for being a service dog..
They sleep in my room at night..And we now have a fence that is 6 foot high/privacy panels..Saved for almost a year! Cost $1400 but worth every penny..I love watching them play 
These 2 dogs have totally changed my life!
I dealt with major depression most of my life..
I no longer have those feelings..
I wake up every morning with a smile and laughing because of them..
I am so truely blessed!!!!!!
I hear that Sheila used to live on the corner up the road..When they moved out..They left her here..Her name back then was Zena..Dunno if that was just what the neighborhood kids called her or what..
When she came to me..There is no way I could have afforded to adopt her from a shelter..We had no fence at the time, so I probably wouldn't have qualified anyways..
Since then however..I have given up whatever it takes to make sure she and Mac have what they need..
I even had a broken leg that I didn't see a doc about (hey it wasn't my -first- broken bone..lol!)
But they get regular checkups, flea meds, quality kibble, beef bones/rawhide for their teeth and heartworm preventative..
Sheila is a chicken killer..Some folks have said I should put her down..But I just do my best to make sure she never gets loose..
At least it was -my- chickens she got ahold of and not the neighbors 
Mac is learning to "protect the babies"
I will probably never leave him alone with chickens..But when I am with him..He minds and knows better..
Ok, this has ended up a lot longer than I planned..
Just my own personal experience