If you have the time to groom your baby then i would keep it long. At 9months old your dog is still shedding its puppy coat which will cause matting. This stopped on my yorkie after he hit a year. But the long hair is high maintnance. Pasta gets combed twice a day to keep his coat silky and matte free. Here is the name of a leave in detangler that i got from my groomer. You can purchase it online. It is AMAZING! Worth every penny. Its by Best Shot Pet Products and its called Ultra Vitalizing Mist. Go to
Best Shot Pet Products Intl. Manufacturer - All Natural Dog Shampoo, Horse Shampoo & Cat Shampoo. Professional Pet Care and Grooming Products! for more information! Whatever you choose to do, your yorkie will still be a cutie!