As I've been struggling with an essay myself I'm going to take pity on you, heheh, but it's not actually very helpful as these sites aren't really neolithic, or if they are, who's to say when the dog bones arrived. This is only what I found with the search button
http://www.themodernantiquarian.com/site/126
http://www.themodernantiquarian.com/post/38785
http://www.themodernantiquarian.com/post/30687
http://www.themodernantiquarian.com/post/21638
http://www.themodernantiquarian.com/post/11385
Perhaps it wasn't the done thing to be buried with your dog. But what does that mean? It's not the done thing now, and people love their dogs very much. Perhaps it's never been nice to sacrifice dogs. They are useful after all and you can't eat them.