A slicker brush, which has wire pins angled so they don't dig into the dog's skin. This will lift out any loose hair and you then remove it from the brush. A chamois leather can then be used to rub down the dog gently to pick up any loose hair remaining and to polish to dog's coat. A teaspoon of vegetable oil a couple of times a week in the food will help the coat condition.
I wouldn't have thought a smooth coat chihuahua would have enough fur to lose to warrant a furminator.