I only went into Superpetz a few times. I'm pretty sure I got pigs ears for my sister's dogs there once, and think I was in there one other time, though I can't remember what for. The place was kind of a Wal Mart for pet paraphernalia, with the non-WalMart touch that you could actually take your pets inside with you.
According to the chain's web site, this was the only Columbia store, which makes me suspect issues with the chain as a whole rather than the standard "things don't do well on Decker" issue. This closing is a further blow to the Fashion Place plaza which housed Superpetz, although it did recently make good the Cici's Pizza vacancy with the opening of Gabby's Pizza in that spot.
(Hat tip to commenter Matt)
UPDATE 8 Oct 2010: Added Phar-Mor to the post title based on the comments.
UPDATE 10 September 2011 -- It appears that Goodwill will be moving across the plaza from its current location in back to this location: