I had this happen on a construction site I was a foreman on many years ago. I happened to be working in a unit on a large housing tract when I noticed a car come onto the property by an access road.
Unfortunately I was some distance from the area but I saw a person get out of the car, open up the rear drivers door and pull out a Golden Retriever. Sure enough the driver pushed the dog away from the car and took off. None of my guys were nearby and I jumped in the company truck and tried to catch the guy but I was too far away. There was an animal shelter nearby so I took the dog to them and called the cops. The dog was old, a male and very friendly. The shelter said they'd do what they could( Me and my guys chipped in about a hundred bucks for the care of the dog). I gave the cops the best description of the car I could, a light blue Ford four door. Couldn't see the plate, the driver was a white guy, looked to be in his mid thirties.
I guess if there is a good news component to these stories, it is that the dogs may end up living with better owners.