Opthalmology Flashcards
farm animal - primary eye diseases
infectious bovine keratoconjunctivitis - fly eye (pink eye/new forest disease)
iritis - silage eye
squamous cell carcinoma - cancer eye
foreign body
farm animal - secondary eye disease
eye lesion as a result of other disease
malignant catarrhal fever
IBR
Listeria
farm animal - systemic state indication in eyes
BVD - cataracts - youngstock, no associated blepharospasm or excessive lacrimation
septicemia - hypopyon - pus in anterior chamber (associated with meningitis)
endotoxemia - congested conjunctiva (Red puffy looking)
dehydration - sunken eyes
Fly eye - causes
spread by flies - more common in summer
moraxella bovis (gram -ve)
more common in youngstock
fly eye - signs
lacrymation - serous initially, can become mucopurulent
blepharospasm
varying degrees of keratitis - fluoroscein
ulceration and corneal pannus - vascularisation and reduction in vision
photophobia - can make handling difficult
pain
unilateral or bilateral
fly eye - treatment
topical antibiotic - cloxacillin - always need this
systemic/subconjunctival antibiotic injection - amoxycillin/oxytetracycline, behind eye
suture - local nerve block then either eyelids together or 3rd eyelid to eyelid - protect eye
eye patch
NSAIDs - very painful
fly eye - risk factors
flies
woodland
dust/chaff
UV light
viral pneumonia - reduced immune system and ocular discharge
fly eye - prevention
fly control - pour on, tags, parasitic wasps, slurry management, ventilation
graze away from woodland
good ventilation
vaccination available
Silage eye - causes
big bale silage feeding - listeria monocytogenes in badly bailed silage
could be secondary to trauma
more common in winter
silage eye - signs
miosis - contricted pupil
blepharospasm
corneal opacity - diffuse or multifocal
glaucoma
fibrin accumulation in anterior chamber
corneal vascularisation in advanced cases
differing from fly eye -
signs on inside of cornea
no corneal ulceration - -ve fluorescein
silage eye - treatment
acute - oxytetracycline and dexamethosone into conjunctiva, topical atropine if miosis
chronic - usually not effective, can resolve without treatment but slowly and can have permanent blindness
silage eye - prevention
remove ring feeder - roll out silage
attention to bailing and wrapping of silage - prevent listeria growth
don’t leave bales open too long
cancer eye - risk factors
squamous cell carcinoma
older beef cattle - <5 yo
breed disposition - hereford and simmental
UV exposure - higher incidence in tropics
cancer eye - signs
unilateral
usually 3rd eyelid but anywhere in conjunctiva
swelling as tumour grows
local invasion of tissues
bad smell
cancer eye - management
surgical excision of 3rd eyelid
enucleation
usually just to hold them over to abattoir - reoccurrence high
encucleation
standing surgery - xylazine and retrobulbar block
elliptical incision around orbit
blunt dissection of conjunctival tissue to access retrobulbar space
ligate optic vessels - orbital packing to control haemorrhage
remove eye - cut optic nerves and vessles
suture eyelids together - simple interrupted - leave space to remove packing
packing removed 3-5 days later
foreign bodies - farm animal eye
straw, grass seed etc
can progress to keratitis
local blocks - easier examination
remove irritant and assess damage
antibiotics and pain relief
malignant catarrhal fever - cause
ovine herpesvirus2 - transmitted from contact with sheep or goats
cattle don’t transmit
malignant catarrhal fever - signs
runny eyes and nose
sudden depression, anorexia, and pyrexia
bilateral eye congestion, keratitis, and corneal opacity from outside in
mucopurulent discharge
leads to blindness
nasal discharge and crusting/sloughing off of muzzle
stomatitis
generalised peripheral lymphadenopathy
enteritis –> diarrhoea
malignant catharral fever - prevention and treatment
diagnosis - antibodies in serum, clinical digns, post mortem
no treatment - euthanasia
prevention - avoid contact with sheep/goats