Most dogs give a warning and most people do not see it.. and so the dog ends up biting.
There is VERY little information in this post and it is all 2nd hand so it is very difficult to advise you. I would recommend you get Jean Donaldson's book "The Culture Clash" as it has extensive discussion about dogs biting people. The book will give you insight as to why and when dogs bite people.
Beyond that, wisdom dictates that the owner get a certified behaviorist (not a trainer) to come and assess the dog and its interaction with its owners and people. There is usually a LOT more going on at some point in the dog's relationship with people than can be described on these threads. A behaviorist (trained and certified) would be able to assess and recommend actions for the owners to take.
There is VERY little information in this post and it is all 2nd hand so it is very difficult to advise you. I would recommend you get Jean Donaldson's book "The Culture Clash" as it has extensive discussion about dogs biting people. The book will give you insight as to why and when dogs bite people.
Beyond that, wisdom dictates that the owner get a certified behaviorist (not a trainer) to come and assess the dog and its interaction with its owners and people. There is usually a LOT more going on at some point in the dog's relationship with people than can be described on these threads. A behaviorist (trained and certified) would be able to assess and recommend actions for the owners to take.
