Diseases Of The Bovine Eye Flashcards
Bovine infectious keratoconjunctivitis (Newforest Eye)
Moraxella bovis - spread by flies (near woodland) in summer
(Others mycoplasma, pneumonia viruses)
CS: lacrimation, blepharospasm, early keratitis (white spot), ulcers / keratitis, ulcers, pannus (vascularisation)
Tx: sub-conjunctival ampicillin, amoxicillin or oxytetracycline best
- cloxacillin (local anaesthetic) BID so impractical
- suture eyelid and 3rd eyelid - similar conditions
- eye patches to relieve irritation
Good response to treatment
Control: Synthetic pyrethroid ear tags / pour ons, permethrin Graze away from woodland Ventilation and fly control indoors Vaccination
Bovine irisitis
Seen in the winter when feeding big bale silage
Listeria monocytogenes
Cs: early - patchy corneal opacity (multifocal unlike NF eye)
Glaucoma
White flecks in the anterior chamber
= uveitis
Tx: atropine - dilate pupil and reduce pain
Dexamethasone sub conjunctival
How can you perform a sub conjunctival injection?
22g light blue needle
Inject into bulbar conjunctiva rather than the palpebral conjunctiva = better absorption
Squamous cell carcinoma
Hereford
UV exposure
White faced animals are at a particular risk
Over 5 years old
Invasive - involves cornea, 3rd eyelid and conjunctiva
Tx- remove the eye
Poor prognosis
Malignant catarrhal fever (secondary eye disease)
Ovine Herpes Virus
Contact with stressed sheep
Usually an isolated case
CS: systemically ill - differentiates from silage eye Pyrexia - 41c Encephalitis - depressed Ulcerations of the oral mucosa Enlarged lymph nodes Respiratory signs Diarrhoea
OCULAR LESIONS: conjunctivitis, eyelid oedema, blepharospasm, corneal opacity (centripetal)
- early lesions start from the outside in, unlike NF eye which starts from the inside out
Euthanise the cow
Infectious Bovine Rhinotracheitis (secondary)
Bovine herpes virus 1
Also causes respiratory disease and abortion
Dx: ELISA
Prev: vaccines
CS: Pyrexia, conjunctivitis and serous discharge, corneal oedema, nasal lesions and discharges
Listeriosis (secondary)
Cs: dry eye keratitis due to facial paralysis (orbital fissure)
= unilateral facial paralysis - droopy ear
Weak jaw tone
Encephalitis - depressed and circling
Tx: high dose penicillin / oxytetracycline
BVD cataracts
Infection between 75-150 days of pregnancy causes cataracts
May also cause cerebellar hypoplasia
What eyes lesions might you see with systemic disease?
Septicaemia - hypopyon and petechiae
Endotoxaemia - injected conjunctiva (petechiae)
Post dystocia - petechiae
Dehydration - sunken
Bracken poisoning - hyphaemia (coagulopathy)
CCN
Causes blindness
Most common neurological disease of calves
Due to a diet change on to a high energy diet - thiaminases are produced in the rumen
CS: early sign - star gazing, negative menace reflex, positive PLR, nystagmus, convulsions, opisthonotonus
Treatment- IV thiamine every 4 hours
Dx - PME
Lead
Causes blindness
Seen at any age
Source - old car batteries, lead
CS: negative menace response, dilated pupils, tremors and convulsion
Dx: lead in the kidney
Tx: CaEDTA and xylazine
Hypovitaminosis A
Causes blindness in calves
Fed on a roots and straw based diet
Increasingly seen in barley beef
CS: OEDEMA OF THE OPTIC DISC
night blindness , negative menace response, dilated pupils
