Dog hates being lead on collar

Question
We got our blue heeler/Samoyed male dog when he was 4mths old he is now 6mths old. I am not sure how his home life was before we got him but in our house we give him lots of love and attention, he's very smart so he was easy to train.  Whenever I take him by the collar with my hand he will fight me with his paws and pull back.  As soon as I let go he is fine.  He comes when called and listens... and he is not generally in trouble when I take him by the collar.  It could be just to show him something and he will not let me take him by the collar.  I would really appreciate some insight into this problem.
Thank you

Answer
Your dog most likely developed this problem because he was forced/coerced by someone, using collar and lead (or possibly just the collar.)  Perhaps someone dragged him to a pile of poop on the floor by his collar, or forced him on leash toward something of which he was quite afraid, or any number of things that entailed hand to collar.

The immediate fix is to fasten a very lightweight nylon leash around a martingale that you can slip over your pup's head without using your hands (but leave his normal collar on as you will be working with  it.)  You can control him by gently coaxing him, with praise and reward, from one place to another.  This will work providing he doesn't have the same fear response to being led on leash, and it's a quick fix while you rehabilitate the collar issue.  If he DOES have a fear of being led on leash by a collar, use a body harness.  Remember to remove the martingale and leash, or the leash on the body harness, if you are not at home.

Once you have a way to lead the dog from one room to another, etc., while praising and rewarding him, you can then begin to change his association with the collar.  Stepping on the end of the leash (so he can't run), squat alongside the puppy and touch the collar lightly while popping a very good treat into his mouth (make sure he smells the treat before you touch the collar).  Tell him he's a good boy, get up and walk away.  Repeat this at random intervals for a week or so until you see absolutely no sign of stress (no ducking of head, flattening of ears, slight backing away, etc.)  Watch the tail. When his tail begins to wag slowly and at body height, you can then hold the collar in your hand lightly while he consumes his treat (while still squatting alongside him, not standing over him).  First few times you do this, make the treat larger than usual (handful of fat free cheese, chicken hot dog, liver treats, etc., rather than just one.)  This is called a "jackpot reward" and should be offered each time the rehabilitation reaches a new threshold.  Next threshold would be for you to be able to grasp and hold the collar while you are standing next to the dog.  Hold it for a few seconds, jackpot; repeat again for several days at random intervals.  Each of these exercises must be done in the least threatening way possible.  At some point (especially when you are now standing next to him) you may see signs of fear returning.  If that occurs, go back to square one for that day and proceed more slowly.  Your goal is to be able to stand IN FRONT OF the pup, reach DOWN and grasp/hold his collar.  These are all very dominant gestures and must be arrived at quite slowly and carefully, observing the pup's body language for any returning fear.  Because your pup is so young, this desensitization routine and retraining might go quite well and easily; however, if he obtained this fear response during the normal puppy fear phase (8 to 10 weeks), it may be far more difficult to rectify.  Please repost and report on how it is going.