My last yorkie, Chelsea, was 5lbs. ZoE is almost double that.
Other than ZoE being much heavier to carry & taking up more room in the bed when she stretches out, there isn't much difference. Chelsea easily jumped on the sofa, chairs, her window seat and mine & my kid's beds and ran up & down stairs no problem. ZoE does all those things too. Neither had any joint issues. I think good breeding & sound health are more important than size.
__________________ (ZoE  )(Chelsea  ) |