One possible theme could be the experience of seeing the world from a different perspective, that of a dog. Another might be about loyalty and friendship, as dogs are often seen as loyal companions in real life. Also, it could touch on the idea of survival in an environment not fully understood from a dog's point of view.
Well, friendship might be a theme. The dog could form bonds with other animals or humans in the story. Also, the concept of home and belonging is likely present. Does the dog find a place where it truly belongs? It may be constantly searching for that throughout the novel.
The main character is likely the dog whose life the story is about. There may also be other characters like the dog's owner, other animals it interacts with such as cats or other dogs, and perhaps some humans in the neighborhood where the dog lives.
The main plot could be about a person who wakes up one day and discovers they are turning into a dog. They might struggle to adapt to their new canine body, like learning to walk on four legs and communicate in a different way.
One possible theme could be freedom. Just like a dog might feel a sense of freedom when running around naked (in a metaphorical sense perhaps), it could symbolize a lack of constraints in the story.
Loyalty is a major theme. In most dog's life short stories, the dog is shown to be extremely loyal to its owner, like in 'Lassie Come - Home'. Another theme is survival. For example, in 'The Call of the Wild', Buck has to fight for his survival in the wild.
Another theme could be the simplicity of life. A dog's life is often centered around basic needs like food, sleep, and play. The story might highlight how these simple things can bring great joy and contentment. Also, the theme of friendship might be present. Whether it's with other animals or with humans, the dog's relationships could be explored to show the importance of friendship.
Probably the dog itself is a main character. It could be a normal dog with a unique personality.
One main theme is the difference between domesticity and wildness. The dog symbolizes domestic life, and the wolf represents the wild.
Survival is often a theme. If the story is set in a tough environment like a cold winter or a dangerous city, the brown dog has to find food, shelter and stay safe. It might have to fight off other animals or avoid getting hit by cars.
The main character is surely the dog. Depending on the story, it could be a specific type of dog like a poodle or a bulldog.