Legal Question in Personal Injury in Massachusetts

I rather doubt that there is any negligence liability here, especially in light of the contributory negligence law (the neighbor's negligence, compared to yours, must be more than 50%). I am not aware of any special rules for dogs that attack other dogs in their own yards, but am happy to be educated by those more expert in dog-bite law. If you had been bitten, there would be strict liability; that may apply to dogs.

I would definitely bring the matter to the attention of the neighbor's homeowner's insurance carrier.

I would agree-I dont see any negligence on your neighbor's part.

I do not agree. It is one thing to have your dog stray, it is another to have the other dog kill yours. I think the problem is your neighbor's. You may consider reporting this matter to the animal control of your town, and seek full indemnification.