So sorry about your loss . . . was your neighbors dog on YOUR property when it happened? Had you warned or said anything to your neighbor about his/her dogs tendencies beforehand? Do you know if anyone else has said anything to this neighbor or if there were prior incidences in which this dog has shown aggression to which the dogs owner was aware of?
Sadely, under the law as it stands now, dogs don't have rights unto themselves. They are considered "chattel," in other words, property. This means that you may be able to get compensation for your economic loses, the purchase prise of your dog and vet bills, perhaps, but that's about it.
Like I posted for the "My Yorkie is too big post," I'm limited in what advice I can give you but the best advice I can offer is to speak to a local attorney, familiar with tort law in your jurisdiction (a local civil trial attorney) and discuss your case with him or her. You may also want to approach the owner of the dog to see if he/she will be reasonable and at least cover your economic losses.
Again, my heart goes out to you.