I am certain that ADHD exists, and can empathise deeply with parents whose children have this diagnosis.
However, I agree with some ABers that the term is often used as a badge of convenience for children who are poorly parented, neglected at crucial stages of emotional /physical development, and are desperate for love and attention by any means.
It can also be a means by which the parents abdicate responsibility for their failure to nurture their children, prefering a diagnosis to a remedy.
I was absolutely horrified when I read that Jack Straw said that some children come to school not knowing their own names, are unable to hold a crayon, and had never seen (or was it read?) a book.
Of course they're desperate for attention, and without trying to make unsuitable and possibly offensive judgements, a dog neglected and/or left on its own will usually become destructive and develop behavioural problems.
I rest my case.