Good thing you checked on them. My heart would've been pounding out of my chest if I witnessed my dogs in that situation. Running the aerator the way you do is another great idea.
One of my dogs fell through after I let her out to potty at 11 PM and I don't run my aerator in the winter. She showed up on the back porch soaking wet and shivering. She looked scared and I was horrified. The next day I could see where she fell in even though it had froze over. I never considered the dangers to them until that day. It was well below freezing that night but temperatures were up and down during the day. I still worry, I make sure they aren't out there too long when the ice could be unsafe or I supervise them. If I ran my aerator in the winter one of my dogs would probably go swimming just because they can

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