Farm Animal Ophthalmology Flashcards
What viruses cause ocular issues in cattle?
BVD
IBR
Malignant catarrhal fever (Ovine herpesvirus-2)
What bacteria cause ocular issues in cattle?
Moraxella bovis (New Forest Eye) Listeria monocytogenes (Silage Eye)
What neoplasias are common in cattle ophthalmology?
SCC
What nutritional issues can cause ocular issues in cattle?
Hypovitaminosis A
Lead poisoning
CCN
What are the clinical signs of BVD in terms of ocular?
- Retinal atrophy
- Optic neuritis
- Cataract
- Microphthalmia with retinal dysplasia
What are the clinical signs of IBR?
• Affects URT (aka ‘red nose’) and eyes
• Conjunctivitis: Hyperaemia and oedema (chemosis)
• Diffuse corneal oedema possible too
• Usually presents as bilateral serous ocular
discharge
What is the treatment for IBR?
Symptomatic
Prevention through vaccination and biosecurity
What are the clinical signs of malignant catarrhal fever in cattle?
- 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)
What is the diagnosis and treatment of malignant catarrhal fever?
- Diagnosis - viral DNA by PCR
* Frequently advise PTS
What is Moraxella bovis?
• Gram-negative, aerobic bacteria causing New Forest Eye
• Found in the eyes of many recovered and
apparently normal cattle
When is New Forest Eye commonly seen?
Summer/early autumn
How is New Forest Eye transmitted?
Cattle are carriers, flies, dust and long grass
What are the clinical signs of New Forest Eye?
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
What is the treatment of New Forest Eye?
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)
What is the cause of Silage Eye?
Listeria monocytogenes, a gram +, microaerophilic bacteria found in poorly fermented alkaline silage
What are the clinical signs of Listeriosis?
- Encephalitis and abortion
- Cranial nerve deficits
- Circling
- Ocular clinical signs: strabismus and nystagmus
- Anterior Uveitis
What is the treatment of Silage Eye?
Chlortetracycline or penicillin
Given in early stages (IM, subconjunctivally)
NSAIDs to reduce inflammation
What ophthalmology issues are seen in sheep?
Infectious keratoconjunctivitis
Silage Eye
Twin lamb
Nutritional as with cattle
What is infectious keratoconjunctivits?
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.
What is the treatment for infectious keratoconjunctivitis?
Oxytet IM and NSAIDs
