Ophthalmology Flashcards
How is an eye examined in cattle?
- Restrain in a crush and tie head round with halter
- Consider sedating if restraint inadequate
- Perform an auricopalpebral block
- Amethocaine?
- Local?
What primary diseases commonly affect cattle eyes?
- Infectious bovine kerato-conjunctivitis (new forest eye, pinkeye)
- Bovine iritis- silage eye
- Squamous cell carcinoma- cancer eye
- What causes new forest eye?
- How does it present?
- How is it treated?
- Morexella bovis
- Lacrymation, blepharospasm, keratitis, ulcer
- Tx
* LA eye ointment- cloxacillin every other day
* Sub- conjunctival injection- oxytet, amoxycillin
* Suture- 3rd eyelids or eyelids only
* Eye patches
* Keep indoors
What are risk factors for pink eye in cattle?
- Flies
- Woodland
- Dust
- Chaff
- UV light
- ‘virus pneumonia’
How is new forest disease prevented in cattle?
- Fly control- ear tags, pour-on, permethrins
- Graze from woodlands
- Ventilation and fly control outside
- Vaccine- USA
- What is bovine iritis also known as?
- What is it associated with?
- What are the clinical signs?
- Silage eye
- Big bale silage feeding, winter
- CS
* Early cases- constricted pupul
* Patchy or multiple areas of corneal opacity
* Glaucoma
* White flocules in anterior chamber
* Later- vascularisation
* Negative to fluorescin
Pathology
Uveitis, hypersensitivity?, listeria?
How is bovine iritis treated?
ABs alone ineffective
Sub-conjunctival injection:
* Atropine
* Dexamethasone
* ± AB
22G needle
What breeds are predisposed to SCC?
What other factor is known?
Herefords
UV exposure
How are SCC treated?
Invasive: remove- may recur
When should enucleation be considered?
- Eyes recover well- give time
- Some clients want to get on
- Warn about handling
- Same approach as SA
- Sedation, local
- Retrobulbar/Peterson block
- What are likely causes of FBs?
- What can it lead to?
- How is it treated?
- Grass seeds, straw
- Keratitis
- Remove- Local
What is secondary eye disease?
- Eye lesions as a feature of a specific disease
- What is malignant catarrhal fever associated with?
- How does it present?
Sheep or wildebeest
* Ovine herpes virus 2
‘Head and eye form’
Persistent pyrexia
Depressed- encephalitits
Nasal and mouth erosions
Lympg nodes enlarged
Resp signs
Diarrhoea
Seology ELISA
What are the eye lesions caused in MCF?
- Conjunctivitis
- Eyelid oedema
- Blepharospasm
- Corneal opacity- centripetal
What is the differential for MCF?
How can it be distringuished?
Blue tongue virus
* Inflammation of the mms- congestion, swelling and haemorrhages
* Sheep worst affected
* Cattle and goats do not show CS
- What causes infectious bovine rhinotracheitis?
- What can cause recrudescence?
- How can it be diagnosed?
- How can it be prevented?
- Herpes virus- BHV-1
- Latent carriers (trigeminal ganglion), recrudescence
- Serology (ELISA), Swabs (immunofluorescence)
- Intra-nasal or IM, marker vaccine
What are the clinical signs of IBR?
- Pyrexia- 41 degrees C
- Conjunctivitis
- Corneal oedema
- Nasal lesions and discharge
- Severe milk drop
Describe the pathogenesis of listeriosis?
How is it treated?
- Infection via V or VII nerve to brain
- Encephalititis
- Circling disease
Unilateral facial paralysis
Depressed
Menace test- retraction
Treatment- oxytet or penicillins
65% recovery
What generalised disease can cause eye lesions?
BVD- cataracts
* can be +ve/-ve
Septicaemia- hypopyon
Endotoxaemia- injected conjunctiva
When might the two following conditions be seen?
Left- sunken eye- dehydration
Petechiae- septicaemia/endotox/post-dystokia
What can cause blood in the anterior chamber?
Bracken poisoning
What can cause acquired blindness?
- CCN
- Lead poisoning
- Vitamin A deficiency
- Twin lamb disease- sheep
What causes CCN?
How is it diagnosed?
- Thiamine (vit B1) deficiency
- Young growing cattle
- Dietary change
- Production in rumen
Diagnosis
* PME- brain fluoresces under UV
What are the signs of CCN?
- Early- star gazing
- -ve menace test
- +ve pupillary response
- Nystagmus and convulsions
- Opistothonus
How is CCN treated?
- IV thiamine every 3-4 hours
- Diet
- Monitor rest of group
- What agents cause lead poisoning?
- What are the clinical signs?
- How is it treated?
- What else needs to be done?
- How is it diagnosed?
- Bateries, lead paint
- Dilated pupils, tremors and convulsions
- Sodium calcium edetate
- Inform DVM- withdrawal
- lead in kidney and history
- Whis is affected by vitamin A deficiency?
- What are the clinical signs?
- Growing cattle indoots- roots and straw diet
- Night blindness, -ve menace, dilated pupils, oedema of optic disk
- Whis is affected by vitamin A deficiency?
- What are the clinical signs?
- Growing cattle indoots- roots and straw diet
- Night blindness, -ve menace, dilated pupils, oedema of optic disk
