Growling, snapping/biting

Our second JRT [Jake] came to us at approximately 1 1/2
years of age - we have two - one female and one male. We do not know much about Jake's early years;
how he was treated, etc.-- we get the feeling that perhaps he was not treated very well. We have had him now for approximately one year and his aggressions seems to be getting worse. He will try to bite the vet when medication via a needle s being administered and if we try to move him for instance, he will growl. I'm not sure of the way to correct him at home when he gets nasty with us or our other pets. At present, I try to do as his Mom might do -- grab him by the scruff of the neck and hold him to the floor/bed or sofa [wherever he happens to be when he acts up] and wait until he submits/calms down. However, sometimes he is in another room or across the room from me and I feel that I can't get to him quickly enough so I usually end up yelling which upsets me, and our other pets who by the way are very loving and kind. I read somewhere about throwing a set of keys so that they land next to the dog to scare him. I haven't done this but I'm getting desperate.

What can I do when he growls/snarls and lounges at our cat or other JRT when he is not within arms reach? Am I doing the right thing by grabbing him by the scruff of the neck and pinning him to the floor, etc?