A dog's tale - a lesson from this story?

hi, i am newbie and more than that English is not my native language. I post this thread to know more about you guys' ideas about this story.
I think many of you did read this story because its short and easy to read. Not bla bla like classic novel , right :lol:
But after reading this story, sth still stuck in my head. It made me confuse, think over/ Whats the lesson Mark Twain wanted to aim?

About the story : ITs a very simple story about a dog ;of course; this dog told about her thoughts and her life. She rescured her master's baby and then her puppy got killed by master himself.

So i think , Mark Twain wanted to point the cruelty of human and the unfair things of this life , right?.A very dramatic scene : one saved the child of the other when her child got killed by the other.
you guys , can you tell your ideas about this story and your comment. Really appreciate your joining:)