13 - equine - pearce Flashcards Preview

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Flashcards in 13 - equine - pearce Deck (84):
1

do horses have better monocular vision or binocular vision?

what is the approximation of how much of each view the horse has?

better monocular vision -> 146*

binocular vision -> 65*

2

what is the total visual panoramic field of the horse (degrees), btwn both monocular field and bonocular field?

350*

3

where are blind spots in horse?

right in front of eyes and below chin
from behind ears to directly behind butt

4

t/f

loss of one eye does not significantly effect a horse's ability to function as it did with both eyes

false

significantly effects horse -> do NOT tell client the horse will be fine as it was before b/c this may set you up for legal problems

horse can live comfortably in the right environment but it will not function as it did before

one eyed horse at a disadvantage and may be more dangerous b/c of this handicapped -> make owner aware

5

how many cones do horses have?

what colors can horse see?

what type of color blind are horses?

2 cones -> blue and red-green

see 2 basic hues -> yellow and blue; NO intermediate colors

"orange, red and light blue color blind"

6

basic needs for an ophthalmic exam in horse?

bright, focal light source
dark environment
magnification

same as with other species

7

is indirect or direct ophthalmoscopy recommended?

why?

indirect

better view of eye
direct is limited to mostly seeing the optic nerve head

8

what is needed for an indirect ophthalmoscopy exam in horse?

light source
16 Diopter lens

9

what size diopter lens for dog?

horse?

16 for horse

28 for dog

10

how to assess vision in horse?

what does pearce think is the best way?

vision directed behavior in stall
tracking
menace response

*best: vision directed behvaior

11

t/f

a good eye exam on a horse does not need sedation

false

12

what drugs are used to sedate a horse during eye exam?

xylazine
detomidine

13

what logistical things are needed for good eye exam of horse?

restraint - stocks, twitch
sedation
topical anesthesia
nerve block

14

what topical anesthetic agent is used MC?

proparacaine

15

what motor nerve block is necessary for exam?

auriculopalpabral nerve block

16

what does the auriculopalpebral nerve block block?

what muscle is paralyzed?
what motion of the horse?

auriculopalpebral branch of the facial nerve (CrN 7)

orbucularis oculi M - akinesia of upper eyelid - horse cannot close eyes well

17

t/f

during the auriculopalpebral nerve block, insert the needle directly into the nerve for most effective block

false

do NOT hit nerve

sub Q injection should be around nerve - then massage the injection site to help with absorption

18

what drug used for the auriculopalpabral nerve block?

2% lidocaine or 2% mepivacaine

19

how long does the auriculopalpebral nerve block last?

lasts 1-3 hours

20

what are landmarks for the auriculopalpebral nerve block?

high point of zygomatic arch
Cd to bony process of frontal bone
Cd to posterior ramus of mandible

N lies on the zygomatic arch

21

t/f

the auriculopalpebral N block blocks both motor and sensory function

false - only motor

22

what regional nerve blocks are done to accomplish sensory nerve block?

lacrimal N
zygomatic N
frontal N
infratrochlear N

23

when are sensory blocks done?

during some exams
for eyelid laceration repair
3rd eyelid surgery
biopsies of periocular area

24

what is NORMAL intraocular pressure (IOP) in horse?

17-28 mmHg

25

what is necessary for accurate IOP measurement?

calm animal
avoid pressure on globe / lids
natural, physiologic head position
sedation and lid block

26

if there is over ____ mmHg pressure difference btwn the eyes, something is wrong

5 mmHg

27

what are 3 MAJOR equine ophthalmologic issues?

keratitis
SCC
equine recurrent uveitis

28

what type of infection are horses prone to in their cornea?

fungal

29

presentation of an acute superficial corneal ulceration?

- distinct borders of epithelium lost
- corneal edema
- absence of cellular infiltrate or malacia of the stroma

30

Tx of superficial corneal ulceration?

ID underlying cause
Px 2* bacT infection
atropine
antifungal***

31

frequency of abx for Tx of acute superficial corneal ulceration?

Tab QID for a week

32

what is fxn of atropine to Tx acute superficial corneal ulceration?

pupillary dilation

33

what is a concern for using atropine in horses?

what is max use to lower risk of this occurring?

gut stasis / ileus may occur

2x day use MAX - more than that inc risk of ileus

34

how to Dx melting or deep stromal ulceration?

corneal cytology and corneal culture

*use sedation and lid block to scrape cornea, NOT eyelids b/c different flora there

35

when should a corneal ulcer be referred?

- over 1/2 stromal depth
- rapidly progressive or melting
- no neovascular response
- perforated and actively leaking

36

when is medical management used in tx of corneal ulceration?

until Sx can be performed

if owner cannot afford surgery

37

t/f

if managed carefully, a deep corneal ulcer can be treated at home with the clients

why or why not?

false

ideal situation is a hospital where it can be medicated every few hours

38

what can be placed inferomedially in the horse's eye to aid in Tx equine eye dzz?

sub palpebral lavage tube

39

what are 2 MC fungal corneal pathogens?

filamentous fungi - molds

Fusarium spp
Aspergillus spp

40

t/f

equine ulcerative keratomycosis is a sight threatening dz, even when well managed and treated appropriately

true

41

describe the pathology of equine ulcerative keratomycosis

presence of fungi

epithelial barrier disrupted -> inoculation of corneal stroma

42

how to dx eq ulcerative keratomycosis?

cytology
culture

43

tx of equine ulcerative keratomycosis?

standard ulcer
topical antifungal
surgery - often required

44

what are 3 Triazoles used to Tx fungal infections in horse?

fluconazole
itraconazole
voriconazole

45

whatt are 2 imidazoles used to Tx fungal infections?

miconazole
ketoconazole

46

what are 3 polyenes used to Tx fungal infections?

natamycin
nystatin
amphotericin B

47

what drug is dr perace's favorite to treat fungal infections associated with a superficial ulcer?

silver sulfadiaziazine

48

what 2 fungal drugs are compounded?

itraconazole
miconazole

49

what 2 fungal drugs are available at a human pharmacy?

voriconazole
natamycin

50

which fungal drug is used off label for equine corneal dz but is well documented and proven to be efficacious?

voriconazole

51

in a corneal abscess, is the epithelium intact or broken?

intact

52

in corneal stromal abscess, what does the corneal stroma look like?

white - yellow stromal infiltrate

53

t/f

a fluorescein stain is positive in the corneal stromal abscess

false

it is negative - epithelium is intact

54

what is MC sequelae to corneal stromal abscess?

2* uveitis

55

t/f

Tx of corneal stromal abscesses is simple and very rapid once initiated

false

long term treatment is needed

tissue heals once it is vascularized

56

how are corneal stromal abscesses treated?

- topical abx every 4-6 hours
- topical atropine to effect
- topical antifungal
- systemic NSAIDs
- maybe systemic abx and anti fungals

57

what abx are used to Tx corneal stromal abscesses?

why is abx selection very important in these cases?

fluroquinolones and chloramphenicol used often


abx must get thru the intact epithelium

58

t/f

common Tx for stromal abscess is Sx excision and graft

false

it is an option but is not done routinely - is only done if response to medical Tx is poor and Sx is required

59

MC tumor of the eye and eyelids in equine?

*also the 2nd MC tumor in horse overall

SCC

60

what structure does the SCC occur on?

3rd eyelid
conjunctiva
cornea
eyelids

61

breed predilection to SCC?

draft breeds
appaloosa
color dilute horses

62

describe behavior of SCC typically

slow to met and most will NOT (6-15%)

but locally invasive

63

if left untreated, what will occur in cases of SCC?

local invasion

64

t/f

surgery alone is best and most effective Tx for SCC

false

Sx alone will lead to 40-60% recurrence of SCC

65

Tx of SCC?

Sx and adjunct therapy

66

best Px for SCC?

UV protection

67

what is MC skin tumor in horses?

sarcoid

68

sarcoid tumors are bengign or malignant?

benign - fibrous tissue

69

what specific etiology is associated with development of equine sarcoids?

bovine papilloma virus

not strong direct link but DNA isolated in lesions via PCR

70

what triggers sarcoids to develop?

trauma and biopsy - handle them carefully

71

in addition to around the eye, where do sarcoids also occur commonly?

around legs

72

what adjunct therapies are used to Tx SCC and sarcoids?

freezing
radiation
hyperthermia
immunotherapy
chemotherapy
photodynamic therapy

73

what breeds are at high risk for equine recurrent uveitis?

Appaloosa
European warmblood
draft breeds

74

t/f

equine recurrent uveitis is a widspread dz but is easily treatable

false

is difficult to treat and frustrating...

75

what is the common dz course of ERU?

initial uveitis episode
periodic uveitis episodes
chronic and recurrent

76

what are acute signs of ERU?

aqueous flare
keratic precipitates
keratitis
vitritis
chorioretinitis

77

c/s of chronic ERU

cataracts
synechia
iris hyperpigmentation
corpora nigra atrophy
glaucoma
blindness
phthisis bulbi => end stage

78

what lesions are seen on the fundus in cases of ERU?

retinal detachment
bird-shot retinopathy
butterfly lesion

79

how is leptospira linked to ERU cases?

when horse is infected w lepto bacT, the body develops immune response to the lepto Ag -> eye tissue is similar to the lepto Ag so the body may attack its own eye, after a lepto infection -> ERU cascade begins

80

what parasitic infection may lead to ERU?

oncocerca cervivcalis worm

81

medical Tx options of ERU?

immunosuppressants - systemic corticosteroids
anti inflammatory drugs - systemic and topical NSAIDs
dilating agent
abx
vax

82

sx tx options of ERU?

cyclosporin implants

83

how effective are cyclosporine implants to Tx ERU?

how does this outcome compare with patients who did not get an implant?

good - for early cases and horses who are visual

CSA has good penetration of ocular tissue and inhibits lepto

15% became blind, but much more than 15% who did not get implant became blind

84

t/f

no matter what we do, most ERU horses become blind

true

56% of ERU horses in 2 years will be blind