Oh boy, well the ADVISE you have been given on the Chihuahua getting mean is false. While it is true any dog can turn mean and without training if dogs like Chihuahuas are treated like babies or dolls they will turn mean. Leash walk your Chihuahua a couple of times a day, teach it the basics, sit stay down and LEAVE IT. Dogs are naturally attracted to kitty poop because cats dont completely digest their food, leaving undigested food around for those ultra sensite dog noses to pick up on and devour. Give your new pup a quality pet food without to many fillers, and keep the table scraps to a minimum, walk and train your dog and if you can remove the cat box to another area where your dog can not get to it, placing it behind a gate (cats can jump from the ground to the top of a refrigerator without issue) or clean it right away until you teach your dog to leave it.
You need to catch your dog in the act, Tell it to drop the offending material, you can shake a soda can which has been filled with dried beans at her, or you can take a dab of toothpaste (you dont need alot) and place it on her tongue after she has grabbed the poop, most dogs hate toothpaste, if you are adverse to toothpaste you can use tobasco sauce. It only takes about three times before they get it and will leave it. Be certain you are feeding your dog enough food tho. Chis should eat small protions a couple times a day since they are so little, Good luck

I totally agree with Mazer that Chihuahuas do NOT turn mean. The mean ones are generally the dogs whose feet never touch the floor, they get carried around every where, never get any kind of training whatsoever, and then suddenly they are not the center of the universe (such as with a child) and they decide whatever is causing them to lose the #1 position in the house must die. If you treat the dog like a dog, with training, you won't have any problems. I know many nice Chis, who are nice even at the vets where they are stressed and getting poked and such.

Thanks for the advice....while we do let her sit on laps during tv time we dont carry her or coddle her,and she is disciplined and taken out for walks on a leash.She seems to adore the baby,sometimes I have them both on my lap at cartoon time...I would think if she was going to be agressive she would have shown signs by now, so I wont worry.She seems to like everybody,even strangers,,so maybe things will be ok. I would hate to give her up,I really like her,and I was one of those people who hated those little yappy lap dogs,especially Chis!!!

Get a covered litter box?

Good luck with your wonderful new puppy.

Dogs love kitty-roca. I bought the self cleaning LitterMaid. It was expensive but I LOVE LOVE LOVE it. My dogs can't eat kitty-roca anymore.

Just make sure that children are not allowed to be mean to the dog. Things kids can do to a larger dog, like lay on it, pull ears, grab tails/legs are things small dogs have to fight against quickly, due to their much more fragile structure.

We had a brindle Chihuahua/terrier mix----we frequently told people he was a miniature pit bull and they believed us---which made it to 20 years of age before getting terminal cancer. He never was afraid of family/friends kids or their friends since all kids were required to treat him with care.