Equine ocular disease- miscellaneous Flashcards Preview

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Flashcards in Equine ocular disease- miscellaneous Deck (23)
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1
Q

What 2 breeds of horse develop uveal cysts from anterior segment dysgenesis?

A

Rocky Mountain Horse (of course)

Connemara pony

2
Q

What can help differentiate uveal cysts from iris melanoma?

A

They do not invade the iris (they are also round and smooth)

3
Q

What location for cysts appear to cause more vision issues in horses?

A

If they are ventral

4
Q

If a uveal cyst is not causing problems in a horse, why might you laser it?

A

They are sometimes associated with behavioral problems and can cause some vision issues, and they get harder to rupture with laser the longer you wait.

5
Q

Horse with BILATERAL lesions at the limbus filled with eosinophils, what is your likely diagnosis? What if there are yellow “sulfur granules” also seen?

A

Eosinophils: r/o eosinophilic keratitis

Eosinophils + sulfur granules: r/o Habronema

6
Q

What type of cyst is uncommon, but can cause exophthalmos in horses?

A

Dentigerous cysts

7
Q

Big, pink fleshy lumps on the conjunctiva/limbus/cornea of a horse. What are 3 DDx, and 1 DDx that is NOT seen in horses that you would include in dogs?

A

1) SCC - usually older (11 yrs)
2) Lymphocytic proliferation - think this in very young horse
3) Orbital fat prolapse - this will be SOFT (vs SCC)

NOT pannus (that is a dog disease)

8
Q

SCC on the third eyelid of horse– how aggressive should you get?

A

Remove 3rd eyelid quickly; these can grow behind the eye, and can kill the horse (note– there are other options available for ocular SCC)

9
Q

What chemotherapeutic is sometimes used topically in horses with SCC?

A

Mitomycin C

10
Q

What breeds of horses are more associated with SCC?

A

Haflinger! Also Appaloosa, Paint, draft (Belgian, Shire, Clydesdale)

11
Q

Where can SCC originate in horses?

A

Cornea, conjunctiva, limbus

12
Q

Although many SCC appear as nodular in horses, how can some appear (making them harder to diagnose)? How is it diagnosed?

A

Stromal infiltrate – keratectomy

13
Q

Is SCC painful?

A

NO

14
Q

Phenylephrine in a horse eye– when does it dilate?

A

Only if used with atropine

15
Q

What causes anterior segment dysgenesis?

A

Issue with the mesoderm or the optic stalk during fetogenesis

16
Q

What is the significance of anterior segment dysgenesis?

A

Generally no huge disruption of vision unless severe

17
Q

What DDx do you need to r/o if you are concerned about anterior segment dysgenesis?

A

Anterior uveitis

18
Q

In severe cases of anterior segment dysgenesis, what can be seen?

A
  1. Microphthalmia
  2. Microphakia
  3. Corneal opacity
19
Q

What are the 4 locations you see SCC?

A
  1. Third eyelid
  2. Limbal
  3. Corneal
  4. Eyelid
20
Q

Which SCC location is most associated with death? Why?

A

3rd eyelid– likes to invade into orbit

21
Q

Which SCC location is most associated with loss of globe?

A

Limbal

22
Q

Which limbus is most commonly affected?

A

Lateral

23
Q

When should MMC NOT be used for SCC?

A

When there is an ulcer (so delay its use post-surgery)