Aggression is one of the main reasons that dogs are euthanised or rehomed; at least 30% of all dogs in rescue centres are there because of the incidence of aggressive behaviour in one form or another. It is actually unusual to have a dog that is aggressing to have just one type of aggression; most dogs have more than one of the following types of behaviour.

It would be prudent, before embarking on a program of aggressive behaviour modification, to rule out any medical reasons for that behaviour, especially if there is a sudden change in the dog