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Medical Index
First Posted: Nov 18, 2010
Nov 17, 2010

Vasculitis, arteritis or anglitis in Horses

by Debora Johnson


What is vasculitis? Can it be cured? Is it hereditary? Can drugs cause it? Can other diseases cause it? Is it caused by bacteria or virus?

What Is Vasculitis?

Different triggers can cause vasculitis. Vasculitis could be described as a condition. It is usually the horses's reaction to its own immune system which is fighting a bacteria, virus, drug reaction, reaction to medication or reaction to an herbal that causes vasculitis. This may lead to inflammation and leakage of fluid which causes pain and edema.


  • Distal limb dermal lesions
  • Lesions on the mucous membranes of the mouth and lips
  • Visual: Reddened areas appear that rapidly form shallow erosions. A scab quickly forms over dermal erosions. (Merck Vet Manual) These lesions are not usually symmetrical.
  • Sometimes the nose, ears, eyelids, cornea, and anus can also have lesions.
  • Edema of the limbs
  • Respiratory, central nervous system or cardiac dysfunction
How Is Vasculitis Diagnosed?

  • Biopsy
  • Blood test (Strep M-protein ELISA (SeM) This may indicate exposure to strangles bacterium. It can indicate purpura hemorrhagica. (Antibodies combine with the bacteria or virus and are deposited in the walls of the blood vessels, leading to inflammation and leakage of fluid. This causes pain and edema (fluid swelling)).
  • Has your horse recently had equine influenza?
  • Vaccination for strangles can trigger purpura hemorrhagica if a horse has been previously exposed.
  • Rickettsial organisms (such as the one that causes Potomac horse fever) can be the cause.
  • Examine any use of drugs or herbals to determine if they may be the offending agent.

  • Determine the cause
  • Penicillin or a similar antibiotic are often used if the cause is determined to be Strep bacteria.
  • Suppress immune system
  • Reduce Inflammation
  • Glucocorticoids are often used
  • Azathiioprine or cyclophosphamide are often used along with the glucocorticoids in the case of non-drug induced cases
  • If drug induced: Stop using the offending drugs

The prognosis often depends upon what caused the vasculitis. If purpura hemorrhagica is the cause horses usually recover without further complications.

For More Information:

Merck Vet Manual/Diseases Involving Immune Complexes
Vasculitis: Just What Does It Mean? (An excellent article)

Medical Index