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Photosensitization

Photosensitivity, Plant-Induced Photosensitisation, Phytophotodermatitis

Photosensitization is an inflammatory skin condition induced by ultraviolet (UV) light exposure. It is caused by ingestion of or direct contact with certain photosensitive-causing plants or medications. Ducks are particularly sensitive on their non-feathered areas of the body, such as on their webbed feet, legs, eyes and bill.

There are several different plants known to contain photosensitive chemicals. The following plants have been reported to cause photosensitization in ducks in the past.
  • Parsley (Petroselinum sativum)
  • Bishop's weed (Ammi majus)
  • Toothpickweed (Ammi visnaga)
  • Cymopterus longipes: This is a perennial herb from the Parsley family. It contains two phototoxic furocoumarins, oxypeucedanin and isoimperitorin, that cause severe acute photosensitization in ducks upon exposure to sunlight.
  • Cymopterus watsonii: This is a phototoxic rangeland plant that is a member of the Parsely family. The leaves and seeds of the spring parsley plant contains furocoumarinas, which cause acute photosensitization in ducks. The stems and roots don't contain the photoactive compounds. Affected birds may later develop leg and feet, beak, and comb and wattle deformities as well as reduced eyesight.
  • Hypericum spp. berries
  • Giant hogweed (Heracleum mantegazzianum): This is a large perennial weed that can reach heights of 15-20 feet. Giant hogweed causes photosensitivity upon contact and subsequent exposure to sunlight. The plant exudes a clear watery sap which contains several photosensitizing furanocoumarins; several of which are known to be carcinogenic and teratogenic. The leaves and roots have the highest concentrations of toxins, during the early part of the growing season.
In severe cases, affected ducks may develop severe crippling deformities to their beak and feet, and sometimes blindness when it affects their eyes.

Symptoms

Chronic lesions of the beak, footweb and eyes
Stunting of the upper beak
Scar tissue formation and thickening of footwebs
Swelling
Sticky eyelids
Lower eyelid ectropion
Dilation of pupils
Redness of eyes
Blindness

Diagnosis

  • History
  • Clinical signs
  • Physical exam
  • Laboratory tests

Treatment

MethodMethod Summary
Reduce or eliminate sunlight exposurefor at least 3 days following ingestion or contact with photosensitive plants.

Prevention

  • Don't allow ducks access to plants which are known to cause photosensitivity in ducks.
  • Do not feed parsley to ducks.

References

Risk Factors

  • Allowing ducks access to areas containing photosensitive plants
  • Feeding ducks parsley

Seasonality

WinterSpringSummerAutumn