DS: Farm Animal Opthalmology Flashcards
What pathogens may cause opthalmolgical problems in cattle?
Viruss
How do viruses affect cattle? Which virsus affect cattle?
- transplacental infection of foetus @ d125-175 of gestation
- final stages of organogenesis of nervous sytem
- development of foetal immune system
> IBR, OHV2
How may IBR affect cattle?
> IBR
- retinal atrophy, optic neuritis, cataract and micropthalmia with retinal dysplasia
- often -> blindness
- affects URT -> “red nose” and eyes
- conjunctivitis (hyperaemia and oedema (chemosis) +- diffuse corneal oedema too)
- usually present as bilateral serous ocular discharge
Tx of IBR in cattle?
- symptomatic
- prevention with vax and biosecurity
Which species does ovine herpes virus 2 affect?
Cattle (transmitted from sheep - cattle)
Clinicla signs of OHV2?
- GI: anorexia, D+
- agalactia
- pyrexia >41*
- RT signs (mucopurulent nasal discharge, severe dyspnoea with stertor d/t nasal cavity exudate, ^ LNs)
- ocular signs (opacity of cornea, unilateral progressing to bilateral, hypopyon may develop but often die first)
Dx of OHV2?
- viral DNA by PCR
- frequently advise PTS
Which bacteria may affect cattle optalmologically?
- Moraxella Bovis (New Forest Eye, Pink Eye) G- aerobe also found in many recovered and apparently normal cattle
- Listeria Monocytogenes (Silage eye) G+ microaerophilic bacteria found in poorly fermented silage
Outline pathophysiology of Moraxella bovis
- multifactorial dz
- cattle carriers
- fomites (flies, dust, long grass), commonly seen summer/early autumn
- tends to be UNIlateral
- tearing and photophobia, conjunctival hyperaemia and chemosis
- corneal changes may follow (oedema, ulceration, abscess may develop -> hypopyon)
- vision los within 3d
Tx Moraxella bovis
- tx early to help resolve problem and help prevent spread
- claxacillin
- tetracycline
- bulbar conjunctival injection
- NOT topical steroids (corneal ulceration risk)
> isolate affected animals during tx and use fly control
Pathophysiology of listeria monocytogenes?
- encephalitis and abortion
- CN deficits
- ocular clinical signs: strabismus and nystagmus
- can also present as SilageEye/Red Eye
- originates directly from silage (inoculated into eye)
Dx listeria monocytongenes?
- tiem of year
- clinical signs
Tx listeria monocytogenes
- Abx, chlortetracycline or penicillin
- given in early stages (IM/SC)
- NSAIDs to reduce inflam
Which neoplasia commonly affects cattle?
> SCC
- malignant neoplasma
- > 5yo
- low pigment = pdf (Herefords with white heads, actinic radiation from the sun)
Outline lesion stages of SCC
- plaque (hyperplastic epithelium)
- papilloma (not malignant, high regression rate)
- SCC in situ (non-invasive)
- invasive SCC (past epithlium’s lamina propria)
Where is SCC commonly seen on cattle?
- sclera
- TE
- eyelid
> mets (invasive tumour) - cervical LNs
Tx SCC in cattle?
- excision usually + enucleation
- bone invasion complication tx (prevents enucleation)
- act early (welfare and financial)
- canot travel to market/slaughter with lcerative lesions of the skin
What nutritional causes of ophthalmic pathology are possible in cattle?
- hypovitaminosis A - complete blindness
- Pb poisoning (no menace, mydriasis, can be followed by blindness)
- cerebro-cortical necrosis - blindness
Which infectious ophthalmic pathology is most common in sheep?
> Infectious Keratoconjunctivitis (Pink Eye) d/t mycoplasma spp.
- Often seen winter d/t housing
- spread via fomites eg. feed troughs
- can be complicated by 2* chlamydia infection
Tx infectious keratoconjunctivitis in sheep?
- oxytetracycline IM
- NSAID
Which eye condition can sheep get which also affect cattle?
- Listeria Monocytongenes (silage eye)
- All nutritional problems
Which condition may pregnant ewes be susceptible to?
Twin lamb disease -> blindness in terminal stages
