"...genetics can influence the behaviour of animals in their adult life, as can the attitudes and behaviour of the owners and early socialisation. Sterilisation, castration, lessons in obedience and hormone treatments can help control and modify aggressive behaviour in the animals. But the real problems derive from the irresponsibility of the owner and the lack of education given to them." Australian Veterinary Association
This is a YouTube video of American Kennel Club Grand Champion, White Rock B'Dazzled By A Knight at the AKC Eukanuba Agility Invitational - Long Beach, CA (December 2006) "Joey" continues to be the only Champion/Grand-Champion AmStaff in the history of the breed to hold the Master Excellent and Master Excellent Jumpers title in agility.
I have also attached a copy of his pedigree, so you can view his ancestry.
If you understand what is required of a balanced working dog, you will appreciate this very good example of a working American Staffordshire Terrier.
These are some more examples of working American Staffordshire Terriers and American Pit Bull Terriers