Mine's a 2yr old Pattrdale Terrier.
Needs to be walked twice a day due his amazing energy levels. I take him on a lead to some nearby fields, where I let him off so he can sprint until he passes out.
Gets very aggresive towards other dogs, regardless of their size.
He could definitely jump your fence... and he'd probably go and kill something (or himself) while he'd escaped.
Very friendly with anyone who will play with him.
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Some people are suggesting that you take a dog from a shelter. While this is a noble gesture, I would recommend buying from a breeder instead.
A lot of the dogs in shelters have some serious psychological issues which will require a lot of attention.