I think it's about a dog, because they "dug a hole in fall" but "she's gone just before the new year" so they probably knew the dog would have to be put down in the near future.
However, I don't think it necessarily has to be a dog because of the chorus, since dogs run and hide when it thunders, I think it's just an interesting reflection on something that happens. Maybe her mind just wanders.
I think it's about a dog, because they "dug a hole in fall" but "she's gone just before the new year" so they probably knew the dog would have to be put down in the near future.
However, I don't think it necessarily has to be a dog because of the chorus, since dogs run and hide when it thunders, I think it's just an interesting reflection on something that happens. Maybe her mind just wanders.