If your long haired Chihuahuas shed lots of hair, just feed them some molasses once or twice a week. This will stop the shedding almost instantly. (They love the taste, it's messy so put it on a little piece of bread for them. It's safe & it works)
Reduce Dog Shedding: 10 ways *Rub furniture with dryer sheets to repel future hair/dust from sticking (DON'T RUB SHEETS ON DOGS-> Highly irritating/harmful for them) I've heard, especially with added fragrance and chemicals.. *Try for a weekly bath with your fave dog shampoo.