Dog Identification-Brands

I just freeze branded some of my dogs with the dry-ice and alcohol method. Hold time was 30 seconds. But about 10 seconds into it, the dogs really started to buck around. I upped the tranquilizer for the rest of them. I was stupid enough to do one without the drug, and that dog hates me!

Years ago, I had my dogs done by a man that used liquid nitrogen and the holding time was 8 seconds. It made good white haired brands on all the dogs, but not on one older female plott, and her skin must have been thinner, because the hair did not grow back and she then had a burn scar for a brand.

I have read on some forums the liquid nitrogen hold time is 15 to 25 seconds (!!!???). Does not make sense to me, because liquid nitrogen is 2-3 times as cold as the dry-ice and alcohol mixture.

Anyone know for sure what the hold time in seconds is for dogs when using liquid nitrogen?

Appreciate an answer if you know! Thanks!