I liked the rhyme pattern. It was unique and I kind of want to try it out. On the third to last line in the last stanza, I would probably change it to "Unbind your heart...", but that's completely your decision.

The parallels of life become apparent when we can empathise in others their difficulties. How do we know what it is like to feel unloved, an outsider and different from the pack. A litter of puppies has its top dog, who looks down to the second in command and so on. The poor 'little puppy' who is left out is something many will be able to relate to.
I am sure that little puppy will find the sun, its new confidence and of course the love it deserves.

Take care.