Farm Animal Ophthalmology

Question 1

What viruses cause ocular issues in cattle?

Answer 1

BVD
IBR
Malignant catarrhal fever (Ovine herpesvirus-2)

Question 2

What bacteria cause ocular issues in cattle?

Answer 2

Moraxella bovis (New Forest Eye)
Listeria monocytogenes (Silage Eye)

Question 3

What neoplasias are common in cattle ophthalmology?

Answer 3

SCC

Question 4

What nutritional issues can cause ocular issues in cattle?

Answer 4

Hypovitaminosis A
Lead poisoning
CCN

Question 5

What are the clinical signs of BVD in terms of ocular?

Answer 5

• Retinal atrophy
• Optic neuritis
• Cataract
• Microphthalmia with retinal dysplasia

Question 6

What are the clinical signs of IBR?

Answer 6

• Affects URT (aka ‘red nose’) and eyes
• Conjunctivitis: Hyperaemia and oedema (chemosis)
• Diffuse corneal oedema possible too
• Usually presents as bilateral serous ocular
discharge

Question 7

What is the treatment for IBR?

Answer 7

Symptomatic

Prevention through vaccination and biosecurity

Question 8

What are the clinical signs of malignant catarrhal fever in cattle?

Answer 8

• GI signs: Anorexia and Diarrhoea
• Agalactia
• Pyrexia (41-41.5C)
• RT signs
• Mucopurulent nasal discharge
• Severe dyspnoea with stertor due to obstruction of nasal cavities with exudates
• Enlarged lymph nodes

Ocular signs including:
• Opacity of the cornea is very commonly seen
• Unilateral at first with progression to bilateral
• Hypopyon may develop (often die first)

Question 9

What is the diagnosis and treatment of malignant catarrhal fever?

Answer 9

• Diagnosis - viral DNA by PCR

* Frequently advise PTS

Question 10

What is Moraxella bovis?

Answer 10

• Gram-negative, aerobic bacteria causing New Forest Eye
• Found in the eyes of many recovered and
apparently normal cattle

Question 11

When is New Forest Eye commonly seen?

Answer 11

Summer/early autumn

Question 12

How is New Forest Eye transmitted?

Answer 12

Cattle are carriers, flies, dust and long grass

Question 13

What are the clinical signs of New Forest Eye?

Answer 13

Tearing and photophobia
Conjunctival hyperaemia and chemosis
Corneal changes may follow: corneal oedema corneal ulceration may follow, corneal abscess may develop hypopyon may ensue
Vision loss may develop within 3 days

Question 14

What is the treatment of New Forest Eye?

Answer 14

Treatment
• Cloxacillin (topical treatment)
• Tetracycline (advisable as often 2º mycoplasma spp)
• Bulbar conjunctival injection
• NSAIDs
• No topical steroid (corneal ulcer risk)
• Can suture up eye (aids with pain control and prevents further damaging by trauma)

Question 15

What is the cause of Silage Eye?

Answer 15

Listeria monocytogenes, a gram +, microaerophilic bacteria found in poorly fermented alkaline silage

Question 16

What are the clinical signs of Listeriosis?

Answer 16

• Encephalitis and abortion
• Cranial nerve deficits
• Circling
• Ocular clinical signs: strabismus and nystagmus
• Anterior Uveitis

Question 17

What is the treatment of Silage Eye?

Answer 17

Chlortetracycline or penicillin
Given in early stages (IM, subconjunctivally)
NSAIDs to reduce inflammation

Question 18

What ophthalmology issues are seen in sheep?

Answer 18

Infectious keratoconjunctivitis
Silage Eye
Twin lamb
Nutritional as with cattle

Question 19

What is infectious keratoconjunctivits?

Answer 19

Also known as pink eye in sheep, cause by Mycoplasma spp. often seen in winter when sheep are in close proximity spread via fomites such as troughs and can be complicated by secondary infectious such as chlamydophilia.

Question 20

What is the treatment for infectious keratoconjunctivitis?

Answer 20

Oxytet IM and NSAIDs