Aminolevulinic acid based photodynamic therapy and diffuse optical reflectance spectroscopy

This thesis explores aminolevulinic acid (ALA)–induced photodynamic therapy (PDT) as a potential treatment for equine sarcoids and canine acanthomatous epulis. ALA is a relatively inexpensive photosensitizing agent that can be administered locally, either topically or by injection, or systemically, and does not cause prolonged photosensitivity. After administration, ALA is metabolized through the heme biosynthetic pathway into protoporphyrin IX (PpIX), the active photosensitizer. Because PpIX is a naturally occurring intermediate that cells efficiently metabolize under normal conditions, treatment‑related photosensitivity is limited in duration. These characteristics make ALA‑based PDT a promising and practical therapeutic approach for veterinary tumors.