VPT 421: Veterinary Toxicology (2+0)

CLASSIFICATION OF PHOTOSENSITIZATION

• Photosensitization is often classified according to the source of the photodynamic agent. These categories are
  • Primary or type I photosensitivity
  • Aberrant endogenous pigment synthesis or type II photosensitivity
  • Secondary (hepatogenous) photosensitivity type III
  • Idiopathic type IV photosensitivity
• A wide range of chemicals, including some that are fungal and bacterial in origin, may act as photosensitizing agents.
• However, most compounds that are important causes of photosensitivity in veterinary medicine are plant-derived.
• Photosensitization occurs worldwide and can affect any species, but is probably most commonly seen in cattle, sheep, goats, and horses.