@ibi_n_sane:
the ears of the basenji of the pictures you show look like their is really something wrong, but it is not right to think that a basenji with a bit thin fur on his ears also has a condition/ disease that causes this.
Of course, this dog is diagnosed with pattern baldness. And no, you can't say that every basenji/dog with less fur on the ears has this condition. Like Tanza said: it could be flies, or maybe cold, malnutrition..
I do think that Tillo's bald blackish ear rims are more than just 'loosing hair because it's winter/spring/summer..' And I would love to know what's causing it. That's why I wanted to ask it at the University and that's why I was suprised to see the B-ears on the screen and to hear about this 'pattern baldness' 🙂