Can anyone give some advice? A friend has been asking for help and I have seen first hand the aggression. In 18 years owning border collies I have never had this problem so hoped someone can help. The pup was neutered at 6 months old, which some behaviourists have said is too young, but it is done now so they can't change anything there.
From 6/7 months of age the dog would growl at any family member that corrected it's behaviour even putting a lead on. He has never been hurt physically by the family.
If he was being stroked he would suddenly flip, start growling and then try to bite, (I saw and example of this) He has become very unpredictable, just someone moving can set him off. They were told to ignore him when he growled at them, so he was the one to back down, but as he is now lunging and biting them if they ignore him they can't continue to do this.
The funny thing is up until 6/7months of age he was as good as gold, going to puppy classes then progressing well in basic training. He is loved to bits, but they cannot continue to live in fear. Their vet has said he is well medically.

Any ideas they can try?

Could be time to get in touch with a professional behaviourist?

no advice i'm afraid but it sounds like they need professional help with a recommended behavourist.

some others on CD may be able to advise.

I have to say I am also in agreement, if this were a pup under 6 months we could advise, you could follow with commitment and turn the pup around, at 18 months this adolescent is in a pattern of behaviour, he has already sussed out what he can and can't get away with he knows his humans very well.

So your friend needs a fresh mind and pair of eyes who can watch and determine the best course of action, someone who will put into action how to control this dog and back up the owner with visits and be on call as they will get to know the dog.  Often a behaviour described by the owner is seen in a different light by the behaviourist, what some think is aggression, is often fear, guarding, pain, that's why you need a proffessional to watch and not an owner to assess.

The problem with neutering a dog so young before fully mature is that the testosterone can act as a back bone with some dogs once neutered before hormones are settled and maturity gained the dog then needs to assert aggression to feel confident, it seems very likely that this is the reasoning for the dogs change in behaviour and unfortunately the clock can not be turned back.

Please get a behviourist, there may even be more than one issue to conquer here. :-)  Any good behviourist should offer reward based therapy, along with time outs, stern voice with strong eye contacts or ignorement, try to look for a recommended behaviourist and please tell your friend to avoid any alpha dominant behaviour, if this is fear aggression brought on by early neutering, then it would be the absolute worst thing to ever do.

Best of luck, by the way plenty of time to still trun him around he is still young, it will take time and patience, but with a good behaviourist it will be done. :-)