Chapter 15 ERU Flashcards
What is Equine Recurrent Uveitis (ERU)?
A condition characterized by multiple recurrent bouts of inflammation of the iris, ciliary body, and choroid, with periods of remission.
What are other names for Equine Recurrent Uveitis?
Moon blindness, iridocyclitis, and periodic ophthalmia.
What is the peak age for the initial uveitis episode in horses?
4-6 years old.
Which horse breeds are predisposed to ERU?
Appaloosa, Warmblood, and American Quarter Horse.
What are the three clinical syndromes of ERU?
Classic, insidious, and posterior ERU.
What characterizes classic ERU?
Active inflammatory episodes in the eye, followed by periods of minimal, chronic ocular inflammation.
What are typical clinical signs of active ERU?
Photophobia, blepharospasm, corneal edema, aqueous flare, hypopyon, miosis, vitreous haze, and chorioretinitis.
What clinical signs are associated with chronic ERU?
Corneal edema, iris fibrosis, posterior synechia, corpora nigra degeneration, miosis, cataract formation, vitreous degeneration, and peripapillary retinal degeneration.
What is insidious ERU?
A form of ERU where inflammation remains at a constant, low-grade level, leading to chronic clinical signs.
Which breeds are most commonly affected by insidious ERU?
Appaloosa and draft breed horses.
What characterizes posterior ERU?
Clinical signs existing entirely in the vitreous and retina, with little or no anterior signs of uveitis.
Which breed is most commonly affected by posterior ERU?
Warmblood horses.
What is primary uveitis?
Acute uveitis caused by various infectious and non-infectious agents.
What systemic disease is commonly associated with ERU?
Leptospirosis.
What role do leptospiral antigens LruA, LruB, and LruC play in ERU?
They cross-react with equine ocular proteins, contributing to the immunopathogenesis of ERU.
What is the blood-ocular barrier?
A barrier that consists of the blood-aqueous barrier and the blood-retinal barrier, preventing large molecules and cells from entering the eye.
What happens when the blood-ocular barrier is disrupted?
Blood products and cells enter the eye, leading to inflammation and immune responses.
What type of inflammatory cells predominantly infiltrate ERU eyes?
CD4+ T cells.
What cytokines do CD4+ T cells secrete in ERU?
Interleukin 2 (IL-2) and interferon-gamma (IFN-gamma).
What role do Th17 cells play in ERU?
They produce IL-17 and IL-23, contributing to the pathogenesis of ERU.
What is epitope spreading?
The diversification of epitope specificity from the initial immune response to other epitopes, contributing to disease progression.
What diagnostic tests help identify primary uveitis causes?
Complete blood count, serum chemistry profiles, serologic tests for specific infectious organisms, and conjunctival biopsies.
What indicates intraocular production of anti-leptospiral antibodies?
A positive C value (intraocular titer greater than serum titer) and detection of organism DNA via PCR.
What are common clinical signs of acute anterior uveitis?
Photophobia, blepharospasm, corneal edema, aqueous flare, hypopyon, miosis, vitreous haze, and chorioretinitis.
What are the main goals of ERU therapy?
Preserve vision and control ocular inflammation.
What treatments are used for acute ERU episodes?
Systemic and local therapy, including antibiotics, corticosteroids, and anti-inflammatory drugs.
What role does cyclosporine (CsA) play in ERU treatment?
It helps prevent recurrent episodes of uveitis by inhibiting T lymphocyte activation.
What are the clinical outcomes of CsA-releasing devices in ERU?
Significantly fewer flares and improved long-term control of ERU.
What is the prognosis for vision in horses with ERU?
Guarded, especially in horses with multiple or frequent episodes of uveitis.
What percentage of horses with leptospiral-associated ERU have unilateral disease?
50%.
What percentage of Appaloosas with ERU have bilateral disease?
Over 80%.
What happens if ERU is unilateral and no bouts occur in the opposite eye for two years?
It is uncommon for uveitis to develop later in the contralateral eye.
What is the long-term prognosis for horses with ERU?
Guarded, with a significant percentage losing vision in one or both eyes.
What is the prevalence of vision-threatening ERU in horses?
At least 1-2% of the horses.
What percentage of horses in Dr. Dwyer’s study lost vision in one or both eyes?
56%.
What percentage of horses with ERU became completely blind in Dr. Dwyer’s study?
20%.
What is the role of molecular mimicry in ERU pathogenesis?
It contributes to the immune response against ocular tissues due to similarity with infectious agents.
What role does bystander activation play in ERU?
It leads to the activation of immune cells that cause tissue damage in the eye.
What are the key clinical signs for diagnosing ERU?
Corneal edema, aqueous flare, posterior synechia, corpora nigra atrophy, cataract formation, vitreous degeneration, and retinal edema or degeneration.
What distinguishes primary uveitis from ERU?
Primary uveitis is a single event, while ERU involves multiple, recurrent episodes of uveitis.
What is the significance of detecting organism DNA in intraocular fluid?
It strongly suggests that the organism is playing a causative role in the uveitis.
What are the suspected antigens associated with the immunopathogenesis of ERU?
Retinal S-antigen, interphotoreceptor retinoid-binding protein, cellular retinaldehyde-binding protein, malate dehydrogenase, neurofilament medium, and leptospiral antigens LruA, LruB, LruC.
What are typical clinical signs of chronic ERU?
Corneal edema, iris fibrosis, posterior synechia, corpora nigra degeneration, miosis, cataract formation, vitreous degeneration, and peripapillary retinal degeneration.
What is the role of immunohistochemistry in studying ERU?
It helps identify the types of inflammatory cells and cytokines involved in the disease.
What are the benefits of CsA implants in ERU treatment?
They reduce the frequency of uveitis flares and help maintain vision in affected horses.
What systemic diseases can cause primary uveitis in horses?
Leptospirosis, onchocerciasis, Streptococcus equi infection, brucellosis, toxoplasmosis, equine herpes virus, equine viral arteritis, parainfluenza type 3, generalized septicemia, endotoxemia, neoplasia, and tooth root abscess.
