I know they make break away collars for cats for this very reason. You may want to check and see if they have anything like this for dogs.
Accidents happen. You can't fault yourself for that. Now that your mindful of it, you can make sure it doesn't happen again.
I'm glad your dogy is ok!
Diesel pickup, lift kit, 10mm, loud exhaust, big dog.... You didn't get enough attention as kid did you?