Regardless of the reason for doing it, killing the dog in the story feels like a cheap emotional ploy. I think it's a common trap for new writers to fall into because we learn pretty quickly that "happy" stories are boring and even a little juvenile. Killing the dog is an easy way to impose grief on a reader because virtually everyone likes dogs.
When I first started college I found the whole experience somewhat perplexing. How do I keep up with all the coursework? How do I pretend to look interested in football? What even is a Student Union??? I attempted to track my progress throughout the year by listing my newfound knowledge in a Word document.
My brother and I grew up in the river. Like tadpoles or insect larvae, we spent our youth maturing in the fetid water. We collected things that floated and things that sank. We collected bottle caps, rubber tires, shiny glass, and rusty old cans. We collected scabs and rashes more than once, and we cleaned each other’s wounds.
The first memory I have of stealing a word was when I was ten years old. It came from a brochure crammed in the pocket behind the driver's seat in a shuttle bus that was taking my family to a beachfront hotel. "Waves crash rhythmically upon the sandy shoreline," it advertised. I plucked the word from the page and I tucked the brochure back into its pocket.