I've recently received solicitations from both SPCA and ASPCA and am wondering if both are worthwhile and what's the difference? Is one actually a front for PETA (I know one of the "humane societies" is)? If I contribute I want to be sure I'm contributing to a worthwhile group.

I think the SPCA is local by cities and ASPCA according to their web site is western hemisphere. I would just donate to your local city SPCA. Better yet donate to BRAT.

Good point - BRAT it is.