[LadyEarth]

My two shorthorn in calf cows have got patches of hair missing over their rumps.  The skin looks very healthy and pink, no scabbiness or exudate.  I watched them for a while and they don't seem to be itchy.  The patches are fairly small (satsuma sized), maybe 6 or 7 in number radiating forwards from the tail.

I can't see any lice or anything that would explain it.  Everything I look up describes scabby or scaly skin and seems to be focussed over the head and neck.

Does anyone have any suggestions as to what it might be?

The yearling calf (AA cross) shows no similar signs...

[darkbrowneggs]

I doubt that is is this but it might be worth googling ringworm


http://www.nadis.org.uk/bulletins/dermatophytosis-“ringworm”.aspx

[farmvet]

lice would be the most likely. Or they're riding each other...is the calf jumping?