With my rescue, I've become pretty adept with keeping e-collars on uncooperative dogs. First, make sure it's attached to a regular dog collar which you then snug up pretty tightly. You can use gauze strips to tie the e-collar to the dog collar, or like my permanent "cone of shame", use wire ties. Don't clip off the wire ties and leave the long ends outside the e-collar, alongside the plastic. For the hard core cases, you may have to use duct tape on the seam where the collar folds over on itself. We had a Corgi mix who went through five collars and two crates and who managed to chew open her spay sutures before I managed the combo that stuck - wire ties, duct tape, and a Kennel Aire Commander crate. Good luck!
Debbie Nosse
Tri-State Corgi Rescue
tscorgirescue.petfinder.com <- home of Princess, the 75lb Corgi