Hi Ronnie, You were completely right about the XXX small being the proper size for both my dogs – great customer service! In fact, even after I cinched the boots tight the Chi’s microscopic hind feet tend to come out of the foot area somewhat – although it didn’t slow her down when she was running. I think when I measured her feet I mostly measured fur. I’m going to try her with some tiny socks I made to see if that fills up the extra space. Both dogs had a 60 minute walk in the snow wearing the boots on separate days and although they acted weird in the house they started running as soon as they got outside – no adjustment period at all! Krista Hewitt