So sorry to hear about this Glen
. Losing pets is so hard. I had an experience like this a few years back, at my exes parents' house. They had two dogs and this exact thing happened to them. Thankfully we were all home when it happened, but it still took about an hour to get the dogs loose from each other and they were both very very distressed, we thought we were going to lose the one who started making a mess all over herself as she flailed. These types collars are quite dangerous. We ultimately got them loose by managing to get scissors under the collar to cut it.
If you need a special collar to help control your dog, I might recommend the Halti collar. Have always used it with my own labs, and it's awkward enough that you definitely won't leave it on after returning from a walk.