[RWebb]

I'm no dermatologist, but does look like poison oak, etc.

try a lipid (olive oil or Kendall MS-NP) and mop it toward the center of the "wound" - not away; discard the paper towels or cloth you use; Technu is the commercial product made for this IIRC

calamine after that

maybe the dog rubbed against her?

also when you bite her back try not to chew so hard