Sorry for your loss. This is one of the reasons I can't STAND overly aggressive animals whether it be males or females, human aggressive or chin aggressive
Cause you just never know when something like this will happen and unfortunately even if you check your chins 3x a day, you know WHEN they get loose it WILL be between checks
That said, I too do the rivet trick...I also double collar some but, in general, not because of aggression issues. I have a VERY small few animals that are THAT aggressive. One is a male, and he's "selectively aggressive" He's beat 3 females where their ears were shredded and their scalp was pretty beat up. Any other male and he'd have been gone but, well, this male has the right stuff and it'd be a total shame to loose him. He's also impregnanted (quickly) several other females and is currently sweet with all his current ladies but I have to be super vigilant introducing new girls to him because he'll either love them...or try to kill them. Otherwise, I have maybe one or two females that would fight with other girls if they got loose but in my herd, that's still pretty minimal.
MOST of my chins are very placid with other chins. For instance (odd story coming). Sometimes when a female is known to be pregnant I shut her off and remove her collar so she can relax a little better. Well, story is one day I was cleaning cages which I do once a week. I don't often weigh my breeding females unless I suspect they're pregnant and want to confirm with weight chart. SO, I spaced out on this one. I was lookin' my girls over and one in particular caught me "odd". After checking her over for a few minutes it dawned on me...where the heck is her collar?!? She was in her cage, never found in another cage? So I began searching her bedding. This turned up NOTHING?!? This leaves two possibilities, either I'd removed it when she littered...forgotten about it and never put one on when I opened her back up to her male (meaning she was uncollared in her cage for at least a month by that point) OR she'd gotten it off the previous week, it'd been buried and discarded in the bedding during cage cleanings (meaning she'd been uncollared in her cage for at least a week). Regardless, she'd never left her cage and caused no problems!
I've double collared several females that had gotten singles off more than twice. NOT because they were aggressive, simply because they like to block the run and live in it when they get the collar off. It's not possible to be bred in the run
Anyhow, knowing your animals and having few aggressive animals really helps minimize horrific instances such as this. Proper collar fitting, spread rivits, and double collaring those that need it also helps. Checking a few times a day doesn't hurt either, but as I said...when things go bad they go bad quickly and it will NEVER been during a collar check
aside from aggressive animals getting their collars OFF...one of my FIRST horrific incidents involved a collar put on too loosely. That particular day I did my morning check and did not check again until late at night when it was feeding time
A girl had apparently tried getting her collar off via slipping it over her head. Well, it was JUST loose enough to get her bottom jaw through wedging the collar into her mouth
she was unable to get the collar back down (or up and over) and was "laid up" for quite a while after that as I recall, from stress.
Again, so sorry for your loss.
