Eye disease in cattle and sheep SDL Flashcards
What does entropion lead to if left untreated in lambs?
Ulceration
Keratitis
Eventual blindness
what sheep have a genetic predisposition to entropion
Border Leicester
Bluefaced Leicester
List 4 ways to treat ent
Mild cases: manual rolling down of the skin immediately below the eyeball
Subconjunctival injection of AB
Insertion of Michel clips
Rarely: surgical correction
How is subconjunctival injection of penicillin used to treat entropion in lambs?
1ml of procaine penicillin injected into lower eyelid introducing needle parallel to palpebral fissure
What is the aetiology of Bovine Keratoconjunctivitus (IBK)?
Most commonly: Moraxella bovis
Mycoplasma spp
Chlamydia spp
Herpes virus
What is the epidemiology of IBK
Flies, close proximity of cattle and fomites play an important role in spread
The disease will spread through a group within a few weeks, often affecting 50-80% of animals.
There appears to be life-long immunity to IBK, and some colostral transfer of protection probably occurs.
List 5 clinical signs of IBK
Epiphora
Blepharospasm
Conjunctivitis
Keratitis with corneal oedema and cloudiness
Pink appearance of the cornea
Describe how IBK is treated in cattle
Ideally stable animal to reduce light irritation and instigate fly control measures
ABs (systemic or topical) and NSAIDs
What AB and dose is used for systemic treatment of IBK
Oxytetracycline at full bodyweight dose
What AB is used as a topical ointment for treatment of IBK
Cloxacillin
Describe how IBK is prevented in cows
Fly control: parasitic wasps, pour ons, hygiene
Autogenous vaccination
Describe the aetiology of listeria monocytogenes ocular infection/silage eye?
Anterior uveitis associated with conjunctival infection with Listeria bacteria
Listeria is ubiquitous and found everywhere
Listeria often found in dangerous quantities in silage that has not fermented sufficiently
What is the signalment of silage eye
sheep and cattle of all ages
when is silage eye most commonly seen
later winter into spring with peak in March
What are the clinical signs of silage eye in sheep and cattle
Profuse discharge from the eye, often overspilling and causing tear-staining on face
Cloudy discolouration of the eye surface, which may be associated with temporary blindness
Bulges of the iris
Cow/sheep unwilling to open eye or allow examination due to pain
Excessive tear production
What are the treatment options for silage eye in sheep and cattle
Bulbar sub-conjunctival administration of gram+ve antimicrobial.
Bulbar sub-conjunctival administration of anti-inflammatory.
Mydriatic sub-conjunctivally.
Topical application of ophthalmic antimicrobial preparation.
+/- systemic antimicrobial / anti-inflammatory
How can silage eye be prevented in sheep and cattle
Pay attention to detail when baling and wrapping to ensure appropriate fermentation conditions limit growth of listeria bacteria.
Try to minimise exposure to air through puncturing or bird attacks and at feed out.
Making bales or clamp silage with a shorter chop length makes it easier for them to feed without having to bury their heads in the long fibres
How are ulcers up to 50% depth treated in sheep and cattle
AB’s (topical or subconjuntival)
Collagenase inhibitors: autogenous serum, 0.2% EDTA, tetracyclines)
NSAIDs
How are ulcers with a depth of over 50% or progressive ulcers treated in sheep and cattle
Third eye flap or tarsorraphy
enculeation
How long does healing of a uncomplicated surface ulcer in sheep and cattle take
5-10 days
How long does healing of deep ulcers in sheep and cattle typically take
2-6 weeks
What is the most common type of neoplasia effecting the eye in cattle and sheep
SSC- Squamous cell carcinoma
What breeds of cattle are predisposed to SSC ocular neoplasia
Herefords and holsteins
What are the common sites of formation of ocular SSC in cattle and sheep
Third eye lid
junction between sclera and cornea
lower eyelid
What are the 4 stages of development of ocular SSC in cattle and sheep
Stage 1: plaque
Stage 2: keratoma or keratoacanthomas
Stage 3: papillomas
Stage 4: carcinomas
How is ocular SSC diagnosed in cattle and sheep
visual examination
What areas of the body should be checked for metastasis in a cow presenting with ocular SSC
Regional LNs
What are the treatment options for ocular SSC in cattle
If effecting the conjunctiva, third eyelid or cornea: surgical excision
Small eyelid lesions can be surgically removed otherwise enucleation
What is the prognosis for ocular SSC in cattle
Recurrence after surgical excision may affect about 1 in 3 patients
What are some examples of systemic diseases with ocular involvement in cattle
Septicaemia resulting in hypopyo
“Head and eye” form of MCF
Infectious bovine rhinotracheitis
BVD
Bleeding disorders
Blindness caused by central lesions
How do congential nasolacrimal duct disorders present in camelids
A history of a wet face caused by the tears spilling out of the eye, a mucopurulent ocular discharge caused by a secondary dacryocystitis, or both
What are the causes of corneal trauma in camelids
Penetration of the cornea with plant material
Recumbency from prolonged anaesthesia
Tick paralysis
Meningeal worms
Lack of passive transfer
How do corneal ulcers appear in camelids
Yellowish-white collections of purulent material at various depths in the corneal stroma; they are often deep
What are the clinical signs of conjunctivitis in camelids
Mild squinting
conjunctival hyperemia
Epiphora (pictured below)
elevation of the eyelids reveals conjunctival hyperemia and possibly chemosis
What can uveitis be secondary to in camelids
Deep ulcerative keratitis
lens induced uveitis
trauma
infectious disease: equine herpesvirus type 1
What are the clinical signs of uveitis in camelids
Mild squinting
Epiphora
Aqueous flare
Red eye
Synaechiae
Corneal oedema
