Intralesional and topical chemotherapy and immunotherapy.

Surgery is the mainstay of treatment for equine tumors. Conservative treatment approaches which preserve function and appearance are increasingly used in clinical practice. This article covers the principles and applications of two conservative treatment modalities including local chemotherapy and immunotherapy. The therapeutic benefit of local chemotherapy is based on the direct drug delivery to tumor tissue, i.e., topical and intratumoral administration of cytotoxic agents in slow release formulation. This treatment modality is very effective for cutaneous tumors and does not result in any permanent damage to normal tissue. Immunotherapy produces antitumor effects primarily through the action of natural host defense mechanisms against tumor cells. Although the use of immunotherapy is still under investigation there are many examples of its successful application to treatment of selected equine tumors.