Bovine ophthalmology Flashcards
What are the main primary diseases of bovine eyes?
Infectious bovine kerato-conjunctivitis - pink eye, new forest eye
Bovine iritis - silage eye
Squmous cell carcinoma - cancer eye
What causes Infectious Bovine Keratoconjunctivitis/New Forest Eye? Clinical signs? Treatment?
Morexella bovis
Poss also Mycoplasma, Pneumonia viruses etc
Lachrymation
Blephorospasm
Ulcers
Treatmnet:
- LA eye ointment (cloxacillin)
- subconjunctival injections (oxytetracycline, ampicillin, amoxycillin), best on bulbar conjunctiva
- suture - third eyelid and eyelids or eyelids only
- eye patches
- photophobia = keep inside
Risk factors for IBK? Prevention?
Flies Woodland Dust Chaff UV light "Virus pneumonia"
Prevention:
- fly control (ear tags, pour ons, permethrins)
- graze away from fly habitat (woodland)
- ventilation and fly control inside
- vaccine in USA
What causes bovine iritis/silage eye? Clinical signs? Treatment?
Associated with big bale silage feeding in winter - uveitis, hypersensitivity reaction?, anecdotal link with Listeria
Clinical signs:
- constricted pupil in early cases
- patchy or multiple areas of corneal opacity
- glaucoma
- white floccules in anterior chamber
- vascularisation later on (inside surface of cornea)
- negative to fluorescein
Treatment:
- antibiotics alone ineffective
- subconjunctival (bulbar) injection of atropine or dexamethasone +/- antibiotic
Which cows get ocular squamous cell carcinomas? Significance? Treatment?
Breed disposition in Herefords >5yo Related to UV exposure Locally invasive - can involve cornea, third eyelid, conjunctiva Remove but may recur
When is Malignant Catarrhal fever seen? Clinical signs?
Associated with sheep or wildebeest cograzing - ovine herpesvirus 2 "Head and eye form" most common Persistent pyrexia 41C Depressed - encephalitis Nasal and mouth erosions Lymph nodes enlarged Respiratory signs Diarrhoea Eye lesions - conjunctivitis, eyelid oedema, blepharospasm, corneal opacity (centripetal)
Infectious Bovine Rhinotracheitits - Aetiology? Diagnosis? Vaccines? Clinical signs?
BHV1 Latent carriers in trigeminal ganglion Recrudescence with stress ELISA serology or swabs for IF Intra nasal or IM marker vaccine - protection in face of outbreak Clinical signs: - pyrexia 41C - conjunctivitis and serous discharge - corneal oedema - nasal lesions and discharge - severe milk drop
Where does Listeriosis infect? Clinical signs? Treatment? Recovery rate?
Infection via V or VII nerve to brain Encephalitis Circling disease Unilateral facial paralysis - droopy ear Dry eye keratitis Depressed Menace test - retraction Treatment - oxytetracycline or penicllins 65% recovery rate
What eye lesions can be caused my BVD, septicaemia and endotoxaemia?
BVD: cataracts - infection between 75-150d of pregnancy but most cataract cases BVDv not found (can be Ag and Ab +ve or -ve), also micropthalmia
Septicaemia: hypopyon
Endotoxaemia: injected conjunctiva
Causes of petechiae in the eye?
Septicaemia
Endotoxaemia
Post dystocia
Potential cause of blood in the anterior chamber?
Bracken poisoning
Causes of blindness?
CCN
Lead poisoning
Vitamin A deficiency
Twin lamb disease in sheep only
What causes cerebrocortical necrosis? Diagnosis? Signs?
Thiamine (vitamine B1) deficiency in young growing cattle/sheep Diagnosis - PME: brain fluoresces under UV light Signs: - star gazing in early cases - -ve menace test: blind - +ve pupillary response to light - nystagmus and convulsions - opisthotonus Treatment: - IV thiamine every 3-4 hours - advise diet change - monitor rest of group
Lead poisoning presentation/clinical signs? Diagnosis? Treatment?
Any age - usually young cattle
Batteries, lead paint etc
-ve menace test
Dilated pupils
Tremors, convulsions
Treatment – Sodium Calcium Edetate (EDTA) IV, sedation, magnesium
Withdrawal periods – inform DVM re: lead in milk and meat
Diagnosis - Pb in kidney, history.
Walk the perimeter of the field to look for sources of lead
Vitamin A deficiency - when seen in cattle? Signs?
Growing cattle indoors Roots and straw diet Night blindness -ve menace test Dilated pupils Oedema of optic disc
