Abstract
Chitosan is one of the natural bioactive materials known for its wound healing effect. Healing of equine’s wounds are often delayed and complicated. This study aimed to evaluate efficacy of chitosan gel on healing of equine skin-wounds in comparison to povidone-iodine (as control). Six adult male donkeys were used and divided equally into two groups; group A (2x2 cm skin-wound) and group B (4x4 cm skin-wound). Full thickness skin-wounds were created on forearms and shoulders. Wounds at the right side were irrigated using povidone-iodine, while wounds at the left side were dressed using chitosan gel. Clinically, chitosan treated wounds contracted faster than control wounds, and shoulder-wounds contracted faster than that of the forearm. By the end of the experiment all chitosan treated wounds were completely healed with intact epidermis. In contrast, 10.4 % and 13.3 % of wound’s area treated with povidone-iodine in group B at the shoulder and the forearm regions, respectively, still unclosed. Grossly, povidone-iodine treated wounds in both regions, were covered with scab in group A, and had an area of granulation tissue in the wound-centers in group B. Chitosan treated wounds, in both groups in both regions, were completely covered with cornified epithelium. Microscopically, the re-epithelialization was uncompleted in povidone-iodine treated wounds in both groups in both regions. In contrary, complete epidermal layer was observed in wounds treated with chitosan in both groups in both regions. Finally, chitosan gel may be better than povidone-iodine in healing of equine skin wounds.

Key words: Chitosan gel, Donkeys, Histopathological changes, Wound healing