I know you are definite that this is dominant dog aggression. I guess I am not so sure. The puppy is 4.5 months old. That is pretty young for that. My girls hump their mothers. They certainly are not more dominant than their mothers. It is just something they do when they are having fun or when the hormones are going crazy because someone is in heat.
I think you need to call in a trainer because you are using all kinds of devices and treating this as dominant dog behavior, and shock collars can actually create problems if used improperly or for some things, and I would not use one with a pup under six months for sure. Same with a prong. People may use the collar to agitate when working the dog in some situations. In any case we are talking about a puppy that is under five months old. These devices really should be used on older pups/dogs if at all. I am not sure that in these circumstances they would not necessarily be the right tool.
I think you got a puppy mix that plays really rough with other dogs. It may have left the litter too soon and have no comprehension of dog-dog communication. Maybe he isn't the right puppy for your situation.
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