Murray E. Fowler, DVM
Basic Wound Healing
A wound into the subcutaneous tissue follows sequential stages of healing, namely inflammation, debridement, proliferation, epithelization and contraction (scarring). Elephant wounds go through the same sequences if allowed to do so. Basic mammalian wound healing involves the epidermis, germinal epithelium, dermis and subcutaneous tissue. In the elephant foot the epidermis becomes the cornified sole, pad or nail, which is produced by the germinal epithelium. The dermis becomes the corium (vascularized fibrous tissue connecting the cornified shell to the digits).
The healing process may take weeks, months and even years. Particular emphasis will be given to anatomy as it relates to foot infections, basic principles of wound healing in mammals as applied to elephants, predisposing factors and factors that inhibit wound healing.
Predisposing Factors of Foot Infections
Genetics (conformation defects), malnutrition (rickets), abnormal behavior (stereotypy, pawing, resting with pressure on a specific area of the foot, excessive pressure to compensate for pain in another limb), degenerative joint disease, poor sanitation, no variation in the enclosure substrate, and minimal opportunity to exercise are such factors.
Cardinal Rules Governing Wound Management, Specifically Foot Infections
1. Elephants should be trained to allow foot inspection of all feet on a daily basis.
2. Minimize or eliminate predisposing factors.
3. Remove all necrotic material, dirt, feces, urine and debris from the wound cavity.
4. Obtain adequate drainage for an exudate to exit the cavity.
5. Prevent recontamination of the clean wound either by packing the wound cavity with disinfectant soaked gauze or by applying a protective boot.
6. Avoid over-zealous trimming once the cavity has been thoroughly cleansed of necrotic tissue and debris and adequate drainage obtained. Avoid trimming back the germinal epithelium as it attempts to cover the granulation tissue.
7. Foot soaks may be used judiciously to accomplish specific purposes. Avoid any solution that may be caustic to the delicate granulation tissue or germinal epithelium. Do not use concentrations higher than recommended.
8. The presence of excessive granulation tissue is likely an indication of the continued presence of debris or foreign material in the wound cavity.
Inhibition of Wound Healing
Factors that act locally include lack of vascularity, denervation, infection, necrotic tissue, hematoma, foreign bodies, mechanical stress, drugs (disinfectants) and trauma (continued débridement). Factors acting systemically include malnutrition, anemia, systemic infection, compromised immune system, temperature at the wound site and age of the elephant.