I definitely would NOT put cat or dog feces in the chicken run. Both cats and dogs can carry tape worms as well as round worms. There are also other diseases which may or may not be animal specific, Toxoplasmosis comes to mind. That's the very reason we're told not to put cat and dog poo in our compost. Also, cat litter would be even more detrimental. If it's the clumping stuff, imagine what it would do inside the chicken when she swallows it... and she will.... she'll think it's some new fangled grit or other chickie treat, well flavored, at that. And if it's the clay based litter, it could also cause a blockage, not to mention any toxins that would be in the clay. It's a bit of a different matter when the chickens are out to free range, and run across Fido's poo, but I wouldn't encourage it, nor would I allow any access to cat litter.