Why not purchase a small bag of the regional red for cats? There's even regional red freeze-dried treats for cats (available on Chewy.com).
Doing a quick glance, there are a few differences between the dog and cat formulas, mainly being licorice root and fennel in the dog, and freeze-dried meats in the cat formula. Not sure how licorice/fennel affect cats?
My cats love it too which is so...weird. One of my cats sneaks bites of the dogs food when I'm not looking. He can't eat the Orijen RR for cats though because its too rich and it makes him throw up. Good to know someone else's cat loves the dog version too
I try not to let him eat it because its the dog version so its deficient in the proper nutrience cats need.