If your cat is positive for  feline leukemia or feline AIDs and it receives (ed) raltegravir (Isentress ®) = a human AIDs  medication, 
thiamine supplement, feline interferon omega or slippery elm bark  in its treatment plan; I would very much appreciate 
knowing what the results  have been. RSH email
  I drew this fanciful image to show you where acral lesions commonly occur. The green circle surrounds two other locations where this problem is common. The amount of scaring and contraction surrounding the wounds tell me that the problem has been present for quite some time. Because this dog is young, large, lean, in apparent good-health and quite apprehensive, I would be suspicious that this dog's problem had a psychological basis rather than an organic one. But every dog that suffers from acral lesions like these should have a complete health work-up in any case, to rule out organic (physical) disease.