Sure...it should not be a problem. I have changed the name of dogs much older than that. One was named 'Spade' when we rescued her off the streets after she was deprived of food and water by her previous owner before being turned out to fend for herself, but she was such a sweet girl who just loved little boys, and the name was just 'not her' so I changed her name to Samantha...Sammie, for short. Because of the differences in the names, and her age, we called her "Sammie Spade" or "Samantha Spade" interspersed with just "Sammie" or "Samantha" until she got used to the new name...which didn't take long, then never called her "Spade" again after she started responding to "Sammie." We found a great home for her...with a family that had little boys, of course.
You may find your dog likes the new name and you will have no problem changing the name, too. I have had dogs and cats who 'preferrred' a different name from the instant they heard the new name, and quit responding to their original name as soon as they had a 'new' name.