Effects of chitosan on experimental abscess with Staphylococcus aureus in dogs

An abscess was developed experimentally by a subcutaneous inoculation of Stapylococcus (S.) aureus T-6 with a 4-cm silk suture in dogs. After draining the pus, the abscess was treated with a suspension of finely granulated chitosan (chitosan group), ampicillin (ampicillin group), or saline (control group) (Day 0). The chitosan group was further divided into 3 subgroups (0.01, 0.1, and 1.0 mg/subgroups). Similar treatment was repeated after 4 days (Day 4), followed by euthanasia on Day 8. The wound cavity contraction rate was calculated by measuring the wound cavity diameter by a sound on Days 0, 4 and 8. The wound cavity contraction rate was significantly higher in the ampicillin, 0.1 mg chitosan, and 1.0 mg chitosan groups than in the 0.01 mg chitosan and control groups on Days 4 and 8 (p < 0.05). In the 0.1 and 1.0 mg chitosan groups, the abscess healed completely in 6 out of 11 (55%), and 9 out of 10 cases (90%), respectively, by Day 8. In the ampicillin group, 4 out of 10 cases (40%) healed completely by Day 8. No healing occurred in the 0.01 mg chitosan and control groups. Histologically, the granulation tissue formed had abundant vascularization in the 0.1 and 1.0 mg chitosan groups on Day 8.