Porphyrin Secretions / Red Tears


Chromodacryorrhea / Red Tears

Chromodacryorhinorrhea / Red nasal secretions

Uroporphyrin / Porphyrin in urine


The excessive production and accumulation of pigmented (pink / rust-colored / orange-red) eye and nasal secretions.

Clinical Signs

  • Pink / rust-colored /orange-red tinged discharge from eyes or nose or both (may be mistaken for blood).
  • May be detected in urine in varying degrees in both healthy and ill rats.


Porphyrins are a group of nitrogen-containing, organic; compounds that help form many important substances in the body, including hemoglobin. These molecules are capable of absorbing ultraviolet light in the visible red wavelength. Porphyrins, in oxidized form, gives the characteristic pinkish-red or “rust-color” to secretions and will fluoresce when viewed under ultraviolet light (e.g., Woods Lamp). The exceptions are those porphyrins that act as intermediates in the heme biosynthetic pathway. Within cells those porphyrins are clear and do not fluoresce until leaving the cells to appear in secretions of tears or blood, or when excreted in urine and feces. Several types of porphyrins can be found in the Harderian gland of rats. The main ones are harderoporphyrin, uroporphyrin, coproporhyrin (pentacarboxylic, hexacarboxylic and heptacarboxylic) in trace amounts, and protoporhyrin IX. Of those, protoporhyrin IX accounts for most of the porphyrin found in the rat’s Harderian gland (Edmyr, 2005).

Harderian or Harder’s gland is an accessory lacrimal gland found on the inner side of the orbit in vertebrates that possess a nictitating membrane (also called third eyelid), and are particularly large in rodents. In the rat, the Harderian gland is irregularly shaped, covering a majority of the posterior surface of the eye, and protrudes medially in the space between the eyeball and the orbital rim. The gland is unified medially but subdivided laterally by three clefts, through which the optic nerve and extraocular muscles pass. The gland comes in contact with the temporal muscle posteriorly, and the duct of the gland opens into the conjunctival sac at the base of the nictitating membrane (Payne, 1994).

The main product produced in the Harderian gland tends to vary between the different groups of vertebrates. In the rat the Harderian gland produces primarily lipids (fats), along with melatonin and porphyrin, which is thought to lubricate both the eye and nictitating membrane. The porphyrin produced by the Harderian gland, in rats, is stored within the gland1. In some rodents the concentration of porphyrins in the Harderian glands varies according to gender and species, and tends to be higher in females than in males. In rats, however, this difference in concentration is not found to be significant (Edmyr, 2005).

The production of porphyrin in the Harderian gland normally increases with age for most of the rat’s life. It was found that twenty-month-old rat’s produce more porphyrin than a rat that is 3 months old. This natural increase of porphyrin production tends to reverse as the rat reaches around the age of two. Thus two-year-old rats will normally produce less porphyrin compared to 20-month-old rats (Rodriguez et al. 1992).

Chromodacryorrhea results when rats secrete sufficient amounts of tears rich in porphyrin from the Harderian gland. As these secretions overflow from the eye and drain through the nasal passages to exit the nares dark rust colored staining, or crust, can be seen around the eyes and nostrils. These secretions may be transferred to the paws and muzzle during grooming. It is normal to see an occasional small amount near the eyes or at the nostrils; however, where there is continuing or increasing amounts an underlying health condition may be present.

The causes for over production of porphyrin secretions in rats may be due to any of the following stressors:

  • Poor nutrition
  • Deprivation of water
  • Pain
  • Illness (e.g., respiratory disease bacterial or viral)
  • Environmental stressors (e.g., aggressive cage-mates, handling, over-crowded cages)
  • Environment and airborne irritants (e.g., aromatic bedding, scented detergent in washed bedding, smoking by owners, candles fragrances)
  • Blocked tear duct
  • Eye infection or other conditions affecting the eye (including injury)

Besides those porphyrins found in the Harderian gland that fluoresce, porphyrin substances are also found naturally in urine and feces as well. It was also found that the porphyrin producing red-pigmented secretions from the Harderian gland, when secreted and groomed by the rat from the eyes and nares, is ingested and thought to be absorbed back into the blood stream, accounting for increased concentration in other organs of fluorescing pigmented porphyrin. Although porphyrin fluorescing may be detected to varying degrees in the urine and feces of both healthy and ill rats, it is not deemed to be a significant diagnostic tool other than to rule out hematuria (blood in urine) or hematochezia (blood in feces).


Case History and Photos

  • Fig. 1: Chromodacryorrhea (Porphyrin secretions), secondary to suspected SDA, in 3 (+) year old rat (Madonna)


Physical assessment

Woods lamp may be used when trying to differentiate if secretions are due to blood or porphyrin (porphyrin fluoresces pink under ultraviolet light source)

Cytology: nose / eye

Urinalysis / urine cytology

X-ray to rule out urolithiasis


Treatment is geared toward the underlying cause for the over-production of the tears or nasal secretions.

Keep eyes and nose cleared of excessive or dried on secretions by gently wiping with warm, damp, cloth.

Nursing Care

  • Ensure healthy environment.
  • Ensure the intake of a healthy diet and fresh water daily.
  • Perform weekly health checks. See Basic and Advance Health Checks in the Health section of Rat Guide.
  • Contact veterinarian at the earliest signs of illness.
  • Follow treatment regimen as prescribed by veterinarian for any suspected illness or injury.
  • Provide any additional supportive care specific to illness or injury determined.
  • Keep eyes and nose clean of secretions.


  • Eyes and nose remain clear and free of accumulated secretions.
  • The underlying condition determined and treated as appropriate.


  • Appropriate cage size for number of rats.
  • Bedding / litter / environment free of dust or aromatic scents.
  • Refrain from smoking in or around rats and their environment.
  • Quarantine of new rats to be added to the existing colony.
  • Identify and correct any issues causing stress.
  1. Hanson, Anne. “Those red tears: porphyrin and the Norway rat” Rat behavior and biology. 6 Feb. 2008. [retrieved 2012]. http://www.ratbehavior.org/porphyrin.htm
  2. Payne AP. The harderian gland: a tercentennial review. J Anat. 1994;185:1–49. [PMC free article][PubMed]
  3. Cui ZJ, Zhou YD, Satoh Y, Habara Y. 2003. A physiological role for protoporphyrin IX photodynamic action in the rat Harderian gland? Acta Physiol Scand. 179(2):149-54.
  4. Edmyr Rosa dos Reis, Ester Maria Danielli Nicola, and Jorge Humberto Nicola. “HARDERIAN GLAND OF WISTAR RATS REVISED AS A PROTOPORPHYRIN IX PRODUCER*.”. Braz. J. Morphol. Sci. (2005) 22(1), 43-51, 17 Mar. 2005. Web. 1 Sept. 2012. .
  5. Cardalda CA, Juknat AA, Princ FG, Batlle A. 1997. Rat harderian gland porphobilinogen deaminase: characterization studies and regulatory action of protoporphyrin IX. Arch Biochem Biophys. 347(1):69-77.
  6. Djeridane Y. 1994. The harderian gland and its excretory duct in the Wistar rat. A histological and ultrastructural study. J Anat. 184 ( Pt 3):553-66.
  7. Djeridane Y. 1996. Comparative histological and ultrastructural studies of the Harderian gland of rodents. Microsc Res Tech. 34(1):28-38.
  8. Djeridane Y, Touitou Y. 2001. Melatonin synthesis in the rat harderian gland: age- and time-related effects. Exp Eye Res. 72(4):487-92.
  9. Payne AP. 1977. Pheromonal effects of Harderian gland homogenates on aggressive behaviour in the hamster. J Endocrinol. 73(1):191-2.
  10. undam Appl Toxicol. 1992 Nov;19(4):538-44. Investigation of factors influencing urinary porphyrin excretion in rats: strain, gender, and age. Bowers MA, Luckhurst CL, Davis HA, Woods JS. Source Department of Environmental Health, University of Washington, Seattle 98195.
  11. Sokolov VE, Bodiak ND, Surov AV. 1994. The possible role of the harderian gland in the chemical communication of the hamster (Mesocricetus auratus Waterhouse, 1839). Izv Akad Nauk Ser Biol. 1994 (6):880-8.
  12. Wetterberg L, Geller E, Yuwiler A. 1970. The mammalian Harderian gland: an extraretinal photoreceptor in neonatal rats? Science 167:884-885
  13. Rodriguez C, Menendez-Pelaez A, Howes KA, Reiter RJ. 1992. Age and food restriction alter the porphyrin concentration and mRNA levels for 5-aminolevulinate synthase in rat Harderian gland. Life Sci. 51(24):1891-7.
  14. Figge, F., Strong, L., Strong, L., & Shanbrom, A. (1942). Fluorescent porphyrins in harderian glands and susceptibility to spontaneous mammary carcinoma in mice. Cancer Research, 2(5), 335-342. Retrieved October 8, 2013, from http://cancerres.aacrjournals.org/content/2/5/335.full.pdf


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