Horse biting at his own knees and stifle?

[Jerry & Susan Milam <milamj@agtelco.com>]

Hey Y'all,

I've noticed a behavior in my youngest gelding that is quite strange to me.

I noticed him doing it a few summers back when we bought a bug zapper to use
near our house. I turned on the zapper and went back down to the barn. Dandy
was in his stall about 50yds away from the zapper and began pacing at first
and then started biting at his knees and his stifles. He was obviously
anxious about the zapper so we never used it again and later found it wasn't
good for what we bought it anyway.

It's been raining quite a bit lately and to save my pasture I bring the herd
into their stalls at times like this  for a few day up to a week. Today I
took the herd out to the round pen so they could roll and romp- head butt
and generally be social creatures. After Dandy had a good roll, he plays
with some of the otheres and then proceeds to start biting himself as I
described already. It seemed as though he wanted to keep playing and nobody
else was in the mood.

That's just my take on the behavior. I see it as a sign of frustration and
anxiety. Anybody have any other ideas what this might be and should I worry
about it?

Thanks,

Susan and Dandy- where it is quite wet right now