Charles Louis Davis and Samuel Wesley Thompson DVM Foundation

For the Advancement of Veterinary and Comparative Pathology

info@cldavis.org | Phone: 847-367-4359 | Fax: 847-247-1869

Go Back

Image: F30330

Pathology Image
  • SPECIES:
    • BOVINE
  • SYSTEM:
    • INTEGUMENT
  • ORGAN:
    • SKIN
  • DIAGNOSIS:
    • TYPE II PHOTOSENSITIZATION (UROPORPHYRINOGEN-3-COSYNTHETASE DEFICIENCY)
  • CONTRIBUTOR:
    • WOLFE
  • INSTITUTION:
    • Cornell University
  • GENPATH:
    • TOXICOLOGIC
  • COMMENTS:
    • Type II photosensitization is a uncommon genetic disease of catle, cats and pigs. Affected animals lack uroporphyrogen-3-cosynthetase, which is required in the incorporation of iron into the heme molecule. This reate-limiting step results in the accumulation of intermediates (uroporphyrin I, coproporphyrin I and protoporphyrin III) in the blood and tissues. In the skin, it is a photo-excitable molecule, utimately resulting in the generation of free radicals and damage to the skin in areas with light pigmentation or haircoat. Pigment also accumulates in bones and teeth resulting in a brown-red discoloration, as well as excreted in the urine which turns brown on exposure to sunlight. Of the three species, only cats have a measurable hemolytic anemia.