BLUE DOGS: Naomi sent this picture:

Naomi wrote: "This was taken last year around Barstow, California, from a man that used to work with Richie. Notice it appears to be a female but it also has those pads on the back."

Well this is a game changer!  Until now, I have always taken it as gospel that only the male blue dogs have the weird pouches on their haunches.  But, as you say, this photograph does definitely appear to be a female; no external genitalia, and, what appear to be nipples hanging down.  I would hazard a guess that this is not just a female, but a female that is, or has recently been, nursing.