My girl's ears never quite stood up all the way unless she was laying or tilting her head a certain way. More or less now she has the half floppy ears and she's 1 and a half year old now. On some occasion when she is suddenly very alert (espcially after getting a haircut) her ears would almost stand up, but not straight up.
We've had in the past a yorkie with total floppy ears and another that had one and a half standing ears lol Our male yorkie had the standing ears and it actually took him over a year for both of them to stand (with one that occasionally flops).
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R.I.P. Mick & Mandy (before 2010), Mila - 4/3/15, Chloe - 2/18/16, Kimchi - 6/2/2021