Photoactive vasculitis is a type of photosensitization wherein inflamed blood vessels allow fluid to leak out into the surrounding tissues causing painful swelling (edema). It is caused by a variety of toxins, viral and other infections, as well as allergic skin reactions. Vasculitis may be caused by toxins in feeds, especially clovers (alsike), goatweed (St. John’s wort, klamath weed), and some varieties of alfalfa, either in hay or grazed.
These toxins interact with sunlight to damage blood vessels in pink skin. This results in blockage of these vessels and lack of blood flow to areas of skin.
This usually appears as hot, painful swelling of pink skinned limbs, especially the hind limbs. The affected areas start out reddened, swollen and very painful to pressure. The skin may slough, leaving open wounds that must heal slowly and require careful wound care for the best cosmetic outcome.
Vasculitis results in patches of severely damaged unpigmented skin resulting from damage to larger vessels and loss of blood supply to skin. Sometimes, however, vasculitis is not confined to these white haired/pink skinned areas.
Diagnosis is usually through clinical exam. A vet usually recognizes this syndrome in unpigmented limbs. Conformation of the diagnosis would require skin biopsy.
Treatment requires protection from light, treatment of damaged skin, and change of management to avoid the photoactive toxins.
Other Diagnoses Considered
Treatments May Include
Prognosis & Relevant Factors
The prognosis is fair. Management must change in order to prevent recurrence.
I Might ObserveRelated Observations
Skills I might need
QUESTIONS TO ASK MY VET
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