Changing Prey

[Bogertophis]

so due to being unable to acquire Frozen rats (of the proper size) for going on 3 weeks now, I was basically forced into feeding him a live mouse today.

not going to lie, it was impressive to watch. It's like he instinctively knew this one was different than the F/T that I'd been feeding him.
was much more of a "stalking" type approach. and the strike and squeeze wasn't as violent looking, but seemed much faster and tighter than the F/T kills were.

will giving him live that one time potentially cause any issues with going back to frozen on his next feeding?

It could. Live prey triggers their instincts with a lot more scent than f/t prey has. It's generally best to avoid offering any live prey when what you want to feed is f/t.

And if you couldn't get frozen rats of the proper size, why not just feed two or 3 f/t mice?

Remember that when a snake is accustomed to taking f/t (or fresh killed prey), they're more likely to make a mistake when grabbing live prey & getting themselves bitten & injured by the prey.

Along with the increased likelihood of future refusals to eat, you also risk pain, suffering & scars for your pet, & vet bills for you, when you switch between f/t & live prey. But it's your call.