While your dog isn't thrilled about reading a sweet card maybe consider dropping by the pet store and bringing a bone, a treat, or an annoying squeaky toy home for the loyal Valentine.
If you walk outside and think to yourself that it is way too hot, put your hand to the ground, literally and if the back of your hand can't handle the heat on the pavement for more than 5 seconds, guess what, your dog can't handle it either!