I couldn't find what it is this year. They posted a list last year though, I remember they had some very nice stuff (like Western pads half-price and so on).
^^ I never received dog deals from them. I assume you have to buy something first? (because I never officially signed for other notifications either, but I shop there from time to time for horse stuff and get horse stuff promotions all the time)
BTW, either horse.com or valleyvet had Days of Christmas too last year. But I haven't received anything for this year as of yet. If I do I'll post it for sure.