im not a expert but i would say that tilly is maybe sencing that smartie is getting on in years and the balance is maybe shifting, as for what you can do about it im not to sure maybe another member may be able to help , i have only experianced it once that was with 2 males i had and the younger one was trying to get the better of the older but it was resolved by the younger dog going to live with some one else as he was not getting on with the older one at all after a while, hope you get some help soon

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