My chihuahua is easily chilled so we've tried doggie sweaters for him. He is just so humiliated wearing them and looks so sad, that we don't leave them on him. He definitely would not wear a halloween costume.
Sasha would be kicking arse and taking names if someone tried to dress her up. She won't even willingly wear her seatbelt in the car.
I will have a go this year, just for you guys, but I'm not promising anything. The reindeer antlers met a swift demise last Christmas, I expect any Halloween outfit to go the same way.
Back when my ferret Luna was still alive, we put a little biker jacket and backwards hat on him and walked him around on a leash for the day-time children's version of Halloween they have the Sunday before/after the actual holiday in my grandparent's development. He was a huge hit with the kids!
sorry this is late but only just got it uploaded and had to show some one, acctually had to show everyone I can. However I think this picture beats the first one I posted.