Awareness of the outside world. In case you were wondering if the issue is still current. A local blacksmith flies a Dixie flag in his vehicle. This means he a) feels strongly enough that he chooses to display it and b) feels confident enough in his clientele that he can.
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In addition to the abscess, Milton’s summer adventures included an intractable case of foot grot. Is it dried mud? Is it ankle scabbies? It is ankle scabbies from the mud.
We threw everything at it. Betadine, steroid cream, pine tar, chlorhexidine spray, Swat, and so on. Some were good. Some were less good. The arsenal kept it from getting worse but couldn’t defeat it. What finally got ahead of the grot was a thorough soaping and letting sit with chlorhexidene shampoo followed by drying followed by generous slatherings of steroid cream.
The Backyard Horse Blog: Spoke Too Soon mentions zinc oxide. We did not use this but I could see how it would work nicely.
YMMV
In fact, the ongoing grot covered up the beginning of the abscess. Apparently an initial mild abscess causes steps that look a lot like a chapped fetlock. Anyone who gets chapped hands in the winter knows how much cracked skin can hurt. I was surprised when I deep scrubbed his fetlocks that I did not find the cracks I was expecting. Hmm, must be something else. Cue abscess treatment.
Rodney had a small amount of grot that cleared up with minimal attention.
Onwards!
Katherine
Virtual Brush Box 
Because we humans think of horses as strong, robust creatures, I’ve always been amazed at how horses can pick up some health or medical issue, that requires some meds and healing. Sounds like you’ve got this one figured out. MM