Not sure if there is an exact age that a pup is considered a senior. I am guessing about 10 for a yorkie. But...it probably also depends upon the health of the pup.
At the age of 8 they are considered adults....and some are healthier than others. I have lost pups at the age of 12 and they were definitely showing their age when they passed. Right now I have a 15 year old foster that is healthy as a horse and actually prances when she is outside. She cracks me up!
