A great dog to me is the perhaps the bet dog there is but a dog tht even once retired or dead still lives in both genetically and thoughtfully. A dog that stocks in your mind when things happen, things that would be trivial to most of people but when a rabbit is caught on a field and you think of that dog or when there offspring no matter how many generations away from the 'great' dog does something you think of tht dog.
A great dog is a loyal dog that has bought joy to the owner and perhaps other people in one way or another