Ophthalmology

Question 1

How is an eye examined in cattle?

Answer 1

• Restrain in a crush and tie head round with halter
• Consider sedating if restraint inadequate
• Perform an auricopalpebral block
• Amethocaine?
• Local?

Question 2

What primary diseases commonly affect cattle eyes?

Answer 2

• Infectious bovine kerato-conjunctivitis (new forest eye, pinkeye)
• Bovine iritis- silage eye
• Squamous cell carcinoma- cancer eye

Question 3

1. What causes new forest eye?
2. How does it present?
3. How is it treated?

Answer 3

1. Morexella bovis
2. Lacrymation, blepharospasm, keratitis, ulcer
3. Tx
   * LA eye ointment- cloxacillin every other day
   * Sub- conjunctival injection- oxytet, amoxycillin
   * Suture- 3rd eyelids or eyelids only
   * Eye patches
   * Keep indoors

Question 4

What are risk factors for pink eye in cattle?

Answer 4

• Flies
• Woodland
• Dust
• Chaff
• UV light
• ‘virus pneumonia’

Question 5

How is new forest disease prevented in cattle?

Answer 5

• Fly control- ear tags, pour-on, permethrins
• Graze from woodlands
• Ventilation and fly control outside
• Vaccine- USA

Question 6

1. What is bovine iritis also known as?
2. What is it associated with?
3. What are the clinical signs?

Answer 6

1. Silage eye
2. Big bale silage feeding, winter
3. 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?

Question 7

How is bovine iritis treated?

Answer 7

ABs alone ineffective
Sub-conjunctival injection:
* Atropine
* Dexamethasone
* ± AB

22G needle

Question 8

What breeds are predisposed to SCC?
What other factor is known?

Answer 8

Herefords

UV exposure

Question 9

How are SCC treated?

Answer 9

Invasive: remove- may recur

Question 10

When should enucleation be considered?

Answer 10

• Eyes recover well- give time
• Some clients want to get on
• Warn about handling
• Same approach as SA
• Sedation, local
• Retrobulbar/Peterson block

Question 11

1. What are likely causes of FBs?
2. What can it lead to?
3. How is it treated?

Answer 11

1. Grass seeds, straw
2. Keratitis
3. Remove- Local

Question 12

What is secondary eye disease?

Answer 12

• Eye lesions as a feature of a specific disease

Question 13

1. What is malignant catarrhal fever associated with?
2. How does it present?

Answer 13

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

Question 14

What are the eye lesions caused in MCF?

Answer 14

• Conjunctivitis
• Eyelid oedema
• Blepharospasm
• Corneal opacity- centripetal

Question 15

What is the differential for MCF?
How can it be distringuished?

Answer 15

Blue tongue virus
* Inflammation of the mms- congestion, swelling and haemorrhages
* Sheep worst affected
* Cattle and goats do not show CS

Question 16

1. What causes infectious bovine rhinotracheitis?
2. What can cause recrudescence?
3. How can it be diagnosed?
4. How can it be prevented?

Answer 16

1. Herpes virus- BHV-1
2. Latent carriers (trigeminal ganglion), recrudescence
3. Serology (ELISA), Swabs (immunofluorescence)
4. Intra-nasal or IM, marker vaccine

Question 17

What are the clinical signs of IBR?

Answer 17

• Pyrexia- 41 degrees C
• Conjunctivitis
• Corneal oedema
• Nasal lesions and discharge
• Severe milk drop

Question 18

Describe the pathogenesis of listeriosis?

How is it treated?

Answer 18

• Infection via V or VII nerve to brain
• Encephalititis
• Circling disease

Unilateral facial paralysis
Depressed
Menace test- retraction

Treatment- oxytet or penicillins

65% recovery

Question 19

What generalised disease can cause eye lesions?

Answer 19

BVD- cataracts
* can be +ve/-ve

Septicaemia- hypopyon

Endotoxaemia- injected conjunctiva

Question 20

When might the two following conditions be seen?

Answer 20

Left- sunken eye- dehydration

Petechiae- septicaemia/endotox/post-dystokia

Question 21

What can cause blood in the anterior chamber?

Answer 21

Bracken poisoning

Question 22

What can cause acquired blindness?

Answer 22

• CCN
• Lead poisoning
• Vitamin A deficiency
• Twin lamb disease- sheep

Question 23

What causes CCN?
How is it diagnosed?

Answer 23

• Thiamine (vit B1) deficiency
• Young growing cattle
• Dietary change
• Production in rumen

Diagnosis
* PME- brain fluoresces under UV

Question 24

What are the signs of CCN?

Answer 24

• Early- star gazing
• -ve menace test
• +ve pupillary response
• Nystagmus and convulsions
• Opistothonus

Question 25

How is CCN treated?

Answer 25

• IV thiamine every 3-4 hours
• Diet
• Monitor rest of group

Question 26

1. What agents cause lead poisoning?
2. What are the clinical signs?
3. How is it treated?
4. What else needs to be done?
5. How is it diagnosed?

Answer 26

1. Bateries, lead paint
2. Dilated pupils, tremors and convulsions
3. Sodium calcium edetate
4. Inform DVM- withdrawal
5. lead in kidney and history

Question 27

1. Whis is affected by vitamin A deficiency?
2. What are the clinical signs?

Answer 27

1. Growing cattle indoots- roots and straw diet
2. Night blindness, -ve menace, dilated pupils, oedema of optic disk

Question 28

1. Whis is affected by vitamin A deficiency?
2. What are the clinical signs?

Answer 28

1. Growing cattle indoots- roots and straw diet
2. Night blindness, -ve menace, dilated pupils, oedema of optic disk