Multimodal therapy of the periorbital equine sarcoid

The treatment of periorbital equine sarcoids can be challenging for practitioners and owners as well. As reported for equine sarcoids in general, tumor growth is independent from gender and can affect horses at all ages. Furthermore the pathogenesis can be multifactorial and all six types reported in literature can occur (occult, verrucose, nodular, fibroblastic, mixed and malignant). The most common complications in correlation with sarcoids without or inadequate therapy are obstruction of the nasolacrimal duct, the functional impairment of the eyelids, exposure keratitis and as a possible result the loss of visual acuity. A total of 15 horses affected by periorbital sarcoids were introduced to the Tierarztliches Kompetenzzentrum Karthaus. Various, modern and already established therapy procedures were used in individual combination. Due to the localisation and restricted resection tissue complete regression could not be achieved by surgical excision alone. The tumor surface was revisoned by a diode laser 810 nm 30 W and fully removed in several sessions. Furthermore the diode laser was used as part of the photodynamic therapy including methylene blue derivate as a photosensitizer. The accumulation of methylene blue with light of specific wavelenght produces reactive oxide, which cause damage to tumour cells itself and the microvaskulature of neoplastic tissue. Chemotherapy included the intratumorale application of mitomycin 1 to 8 times every 2 to 3 weeks. Furthermore each patient received Aciclovir, an antiviral, as topical treatment once daily. Elaborately follw-up care and periodic checkups are essential to achieve satisfying long-term results. Of the 15 treated horses total regression was accomplished in 13 cases and no tumor recurrence could be detected during observation period of at least 11 months. In one advanced tumour case attenuation of symptomes was reported. Unfortunalety therapy was cancelled in one patient due to restricted financial means. The cases described above could reveal, that combined use of several modern therapy procedures, a so called multimodal therapy, represents an effective and targeted treatment of periorbital sarcoids in horses.