The animation was really nice.
The story was heartbreaking for a bit in that the dog was alone and unloved for so long and then when his owner comes home. He has to compete with her lover for affection and attention. Hilarity ensues. Kind of funny how it ends with what seems to be the two starting to get used to each other but the rivalry is going to be quite strong for awhile.
The music used being your own original work is also nice, I liked that a lot.
The graphics were nice and reminded me of some older music videos here on Newgrounds. I look forward to seeing more like this in the future.
Overall, looks nice, you have a new fan now. :)