My springer spaniel bitch is what my vet once described as 'the dog version of autistic'.
I absolutely know that she isn't autistic as such, but she runs up to people she doesn't know as though she is longing to be stroked and fussed - and then when the person tries to do just that she screams, like a banshee, and behaves as though she has been fatally injured.
She is 5 now, we have had her from a puppy, she came from a lovely home - mum & dad are family pets, and the litter was a one off of 4 puppies - the other 3 are all fine.
She is REALLY hard work, everyone has to be told not to look at her, talk to her or stroke her - she is also very pretty, so taking her for a walk anywhere busy is a complete nightmare as people always want to touch her. As is having visitors - unless they completely ignore her and then she is usually sat on their lap after an hour.
She responds well to cheese, so going to the vets involves taking a lot of cheese cut up, having my arm around her so she can't see the vet and constant pieces of cheese into her mouth - the vet can do what she wants to her then and she doesn't flinch.