I'm fairly luck too, Zhoie will go in the snow or rain...you know when nature calls...
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I can tell she isn't happy about getting her feet wet in the rain, she will actually leap across the yard, like a deer to find that special dump spot and then runs like a bat out of h~ll to get back to the garage.
When it's colder out and raining, she has raincoats but I've yet to get her to wear the hood.
Try a raincoat, it works wonders and they do get use to walking in boots, just takes awhile. Zhoie wears hers in the snow.