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Equine Clinical Immunology > Chapter 15 ERU > Flashcards

Chapter 15 ERU Flashcards

1
Q

What is Equine Recurrent Uveitis (ERU)?

A

A condition characterized by multiple recurrent bouts of inflammation of the iris, ciliary body, and choroid, with periods of remission.

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2
Q

What are other names for Equine Recurrent Uveitis?

A

Moon blindness, iridocyclitis, and periodic ophthalmia.

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3
Q

What is the peak age for the initial uveitis episode in horses?

A

4-6 years old.

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4
Q

Which horse breeds are predisposed to ERU?

A

Appaloosa, Warmblood, and American Quarter Horse.

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5
Q

What are the three clinical syndromes of ERU?

A

Classic, insidious, and posterior ERU.

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6
Q

What characterizes classic ERU?

A

Active inflammatory episodes in the eye, followed by periods of minimal, chronic ocular inflammation.

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7
Q

What are typical clinical signs of active ERU?

A

Photophobia, blepharospasm, corneal edema, aqueous flare, hypopyon, miosis, vitreous haze, and chorioretinitis.

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8
Q

What clinical signs are associated with chronic ERU?

A

Corneal edema, iris fibrosis, posterior synechia, corpora nigra degeneration, miosis, cataract formation, vitreous degeneration, and peripapillary retinal degeneration.

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9
Q

What is insidious ERU?

A

A form of ERU where inflammation remains at a constant, low-grade level, leading to chronic clinical signs.

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10
Q

Which breeds are most commonly affected by insidious ERU?

A

Appaloosa and draft breed horses.

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11
Q

What characterizes posterior ERU?

A

Clinical signs existing entirely in the vitreous and retina, with little or no anterior signs of uveitis.

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12
Q

Which breed is most commonly affected by posterior ERU?

A

Warmblood horses.

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13
Q

What is primary uveitis?

A

Acute uveitis caused by various infectious and non-infectious agents.

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14
Q

What systemic disease is commonly associated with ERU?

A

Leptospirosis.

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15
Q

What role do leptospiral antigens LruA, LruB, and LruC play in ERU?

A

They cross-react with equine ocular proteins, contributing to the immunopathogenesis of ERU.

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16
Q

What is the blood-ocular barrier?

A

A barrier that consists of the blood-aqueous barrier and the blood-retinal barrier, preventing large molecules and cells from entering the eye.

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17
Q

What happens when the blood-ocular barrier is disrupted?

A

Blood products and cells enter the eye, leading to inflammation and immune responses.

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18
Q

What type of inflammatory cells predominantly infiltrate ERU eyes?

A

CD4+ T cells.

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19
Q

What cytokines do CD4+ T cells secrete in ERU?

A

Interleukin 2 (IL-2) and interferon-gamma (IFN-gamma).

20
Q

What role do Th17 cells play in ERU?

A

They produce IL-17 and IL-23, contributing to the pathogenesis of ERU.

21
Q

What is epitope spreading?

A

The diversification of epitope specificity from the initial immune response to other epitopes, contributing to disease progression.

22
Q

What diagnostic tests help identify primary uveitis causes?

A

Complete blood count, serum chemistry profiles, serologic tests for specific infectious organisms, and conjunctival biopsies.

23
Q

What indicates intraocular production of anti-leptospiral antibodies?

A

A positive C value (intraocular titer greater than serum titer) and detection of organism DNA via PCR.

24
Q

What are common clinical signs of acute anterior uveitis?

A

Photophobia, blepharospasm, corneal edema, aqueous flare, hypopyon, miosis, vitreous haze, and chorioretinitis.

25
Q

What are the main goals of ERU therapy?

A

Preserve vision and control ocular inflammation.

26
Q

What treatments are used for acute ERU episodes?

A

Systemic and local therapy, including antibiotics, corticosteroids, and anti-inflammatory drugs.

27
Q

What role does cyclosporine (CsA) play in ERU treatment?

A

It helps prevent recurrent episodes of uveitis by inhibiting T lymphocyte activation.

28
Q

What are the clinical outcomes of CsA-releasing devices in ERU?

A

Significantly fewer flares and improved long-term control of ERU.

29
Q

What is the prognosis for vision in horses with ERU?

A

Guarded, especially in horses with multiple or frequent episodes of uveitis.

30
Q

What percentage of horses with leptospiral-associated ERU have unilateral disease?

A

50%.

31
Q

What percentage of Appaloosas with ERU have bilateral disease?

A

Over 80%.

32
Q

What happens if ERU is unilateral and no bouts occur in the opposite eye for two years?

A

It is uncommon for uveitis to develop later in the contralateral eye.

33
Q

What is the long-term prognosis for horses with ERU?

A

Guarded, with a significant percentage losing vision in one or both eyes.

34
Q

What is the prevalence of vision-threatening ERU in horses?

A

At least 1-2% of the horses.

35
Q

What percentage of horses in Dr. Dwyer’s study lost vision in one or both eyes?

A

56%.

36
Q

What percentage of horses with ERU became completely blind in Dr. Dwyer’s study?

A

20%.

37
Q

What is the role of molecular mimicry in ERU pathogenesis?

A

It contributes to the immune response against ocular tissues due to similarity with infectious agents.

38
Q

What role does bystander activation play in ERU?

A

It leads to the activation of immune cells that cause tissue damage in the eye.

39
Q

What are the key clinical signs for diagnosing ERU?

A

Corneal edema, aqueous flare, posterior synechia, corpora nigra atrophy, cataract formation, vitreous degeneration, and retinal edema or degeneration.

40
Q

What distinguishes primary uveitis from ERU?

A

Primary uveitis is a single event, while ERU involves multiple, recurrent episodes of uveitis.

41
Q

What is the significance of detecting organism DNA in intraocular fluid?

A

It strongly suggests that the organism is playing a causative role in the uveitis.

42
Q

What are the suspected antigens associated with the immunopathogenesis of ERU?

A

Retinal S-antigen, interphotoreceptor retinoid-binding protein, cellular retinaldehyde-binding protein, malate dehydrogenase, neurofilament medium, and leptospiral antigens LruA, LruB, LruC.

43
Q

What are typical clinical signs of chronic ERU?

A

Corneal edema, iris fibrosis, posterior synechia, corpora nigra degeneration, miosis, cataract formation, vitreous degeneration, and peripapillary retinal degeneration.

44
Q

What is the role of immunohistochemistry in studying ERU?

A

It helps identify the types of inflammatory cells and cytokines involved in the disease.

45
Q

What are the benefits of CsA implants in ERU treatment?

A

They reduce the frequency of uveitis flares and help maintain vision in affected horses.

46
Q

What systemic diseases can cause primary uveitis in horses?

A

Leptospirosis, onchocerciasis, Streptococcus equi infection, brucellosis, toxoplasmosis, equine herpes virus, equine viral arteritis, parainfluenza type 3, generalized septicemia, endotoxemia, neoplasia, and tooth root abscess.

Equine Clinical Immunology (32 decks)

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