a friend of mine has got a 12 week old black cocker spaniel from what I assume is a puppy farm( a place that has several breeds for sale  all the time) Anyway, since she bought it home it hasnt had any encounters with dogs but both times she took her to the vets it was terrified of other dogs and screamed and tried to bury itself in her neck, even though the dogs were not particularly interested in her.
i was going to introduce my dog to her but on hearing this thought the better of it. we let them "see" each other at a distance of 10 feet with mine in the car looking out the window and hers being held, even this was too much for the dog. my question on her behalf is how best to go about socialising this puppy?

Oh dear, that is not a good start is it, you know pups aren't actually born knowing that they are dogs! Even though she has come from a multi dog breeder (being polite, but it may still be the case) she may have never actually seen the other dogs just heard them and so does not recognise her own species, she probably fears them as preditors.  This is what socialising is all about.

Flipside she may have been attacked by one of the other dogs and her confidence is shattered.

First steps, I would have your friend invite you and your dog (who hopefully is calm and really good with other dogs?) over to her house, (that way the pup is feeling safer in her own territory) pop the pup on her lap and sit across from them with your dog, eventually the pup may become inquisitive enough to investigate your dog, but otherwise just get your dog to sit nicely whilst you chat. (Keep your dog on a lead)  If all goes well the pup should make her first friend, if ehe is still terrified then do this as often as possible, until she realises all is well. Your friend needs to get her out and about quickly and experiencing all noises, people and places as well as other dogs.

It can be overcome.  One of my puppies was the same, not through any bad experience or lack of attempts at socialisation.  She didn't run screaming from all dogs though.  The big ones she felt were okay it was just little ones, even the most friendly and placid of them, that sent her screaming for cover.  With patience she over came all of it and now wants to investigate everything. 

All you can do is to keep trying them with other friendly dogs.

surely the pup would of been with the bitch and the litter mates thougth? its mother woudl of been the first living thing the pup would of ever seen. maybe the pup did have a bad experience, maybe it was the vets its self that scared the pup.

my boxer was rescued by the rspca from a puppy farmer, he was with the bitch and 5 other litter mates in a cage. however he had already been docked, vaccinated and microchipped. they want to get the pups done asap so they can sell them asap.

it could even be a behavioural issue, or some sort of mental problem, as a lot of puppy farmers in breed there pups, im sure i read somewhere about there being a link with puppies from puppie mills and behavioural/mental problems.

It does not matter how many siblings or in fact how many dogs are at home, dogs MUST be socialised with others outside their own "pack" just as our children need to meet other than their own family to learn manners and how to read different people etc.

Unfortunately whilst people insist on purchasing animals from these places they will reap the consequences.........

A really good puppy class would help your friend's dog overcome his/her fear.

Tell her to look for one that is very controlled and doesn't just let all the dogs off-lead to sink or swim. A good trainer will assess the pup and will carefully organise meeting s/he can cope with to gradually build up confidence.

She needs to start socialising this pup as soon as possible before the 'window of opportunity' for successful socialisation closes after which the whole process will take much longer and be more stressful for the pup.