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Diagnosis and treatment of secondary ocular diseases in horses (Proceedings)

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Aug 01, 2009

Equine recurrent uveitis
Etiology of ERU

  • No Single Cause Identified
  • Infectious Agent Association

o Trigger or Initiating factor
o Disruption of blood ocular barrier
o Activation of immune response in the eye

  • Antibodies to foreign antigens
  • Antibodies to self antigens
  • Ultimately an immune-mediated disease

Equine recurrent uveitis

Any disease capable of producing a chronic or recurrent sensitization of the vascular tunic of the eye. ERU is an immune-mediated disease characterized by delayed hypersensitivity reactions. Potential etiologies include keratouveitis; microbial infections - Leptospira spp. (L. pomona most commonly implicated), Brucella abortus, Streptococcus spp. (Streptococcus equi); Toxoplasma gondii; parainfluenza-3 virus (PI-3); equine viral arteritis virus (EVA); equine influenza virus (EIV); and parasitic infections - Onchocerca cervicalis microfilaria, Strongylus vulgaris. Other suggested inciting conditions include fungi, Chlamydia, mycoplasma, dental abscesses, endotoxemias (pyelonephritis, endometritis), lymphatic neoplasia, blood dyscrasias, and uveal tract trauma with secondary immune reaction.

Leptospirosis and uveitis

  • Strong relationship shown

o Horses w/serum titers >100

  • 13.2 x more likely to show signs of uveitits
  • 4.4 x more likely to lose vision

o Appaloosas w/ serum titers >100

  • 8.3 x more likely to develop uveitis than other breeds
  • 3.8 x more likely to lose vision after developing dz

o Ocular signs come late

  • 12-15 months after inoculation