title: Porphyrins are not present in feline ocular tissues or corneal sequestra.
abstract: OBJECTIVE
  To determine if feline lacrimal glands, glands of the third eyelid, corneas, and corneal sequestra contain porphyrins, which could be responsible for the brown/amber discoloration of corneal sequestra and tears in affected cats.
  
  
  METHODS
  Samples of grossly normal cornea, lacrimal gland, gland of the third eyelid, and sequestra obtained via keratectomy were collected. Porphyrin concentrations of the homogenate were determined by spectrofluorometry with protoporphyrin IX and coproporphyrin III dihydrochloride used as standards. A hamster harderian gland was used as a positive control.
  
  
  RESULTS
  Normal tissues were harvested from one eye each of 14 nonclient owned, adult, mixed-breed, short-hair cats euthanized for reasons not associated with this study. Eighteen sequestra were acquired from cats undergoing unilateral lamellar keratectomies. Breeds of the affected cats included eight Himalayan, five domestic shorthair, and one each of four other breeds. Only the positive control and standards contained levels of porphyrins above background. All feline samples examined were histologically normal with no evidence of porphyrins.
  
  
  CONCLUSIONS
  Porphyrins are absent in normal feline lacrimal glands, corneas, and corneal sequestra. Porphyrins do not appear to be the cause of the brown/amber color of feline corneal sequestra.
authors.affiliation: Department of Pathobiology, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA. knewkirk@utk.edu
authors.forename: Kim M
authors.initials: KM
authors.lastname: Newkirk
authors.forename: Diane V H
authors.initials: DV
authors.lastname: Hendrix
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Keller
mesh_terms: D000818:Animals; D002415:Cats; D003315:Cornea / Q000737:chemistry*; D003316:Corneal Diseases / Q000378:metabolism / Q000662:veterinary; D005123:Eye / Q000737:chemistry; D006243:Harderian Gland / Q000737:chemistry; D007765:Lacrimal Apparatus / Q000737:chemistry*; D010860:Pigments, Biological / Q000032:analysis; D011166:Porphyrins / Q000032:analysis*; D013666:Tears / Q000737:chemistry
chemical_list: D010860:Pigments, Biological; D011166:Porphyrins