Diseases of the bovine eye Flashcards
What are primary diseases of the eye?
- Infectious bovine kerato-conjunctivitis - New Forest eye, Pinkeye
- Bovine iritis - silage eye
- Squamous cell carcinoma - cancer eye
What causes New forest eye?
- Moraxella bovis
-sometimes mycoplasma spp
What can IBK present as?
- Lachrymation
- Blepharospasm
- Keratitis
- Ulcer
- Pannus - vascularisation
What is treatment of new forest eye?
- LA eye ointment (orbenin-cloxacillin)
- Sub-conjunctival injection - oxytet
- Suture - eyelids
- Eye patches
- Photophobia = keep indoors
What are risk factors for IBK?
- Flies
- Woodland
- Dust
- Chaff
- UV light
- Virus / pneumonia
How can you prevent new forest eye?
- Fly control - ear tags, pour-ons, permethrins
- Graze away from fly habitat
- Ventilation + fly control inside
- Vaccine - USA
What is bovine iritis associated with?
- Big bale silage feeding
- Winter
- Immune mediated reaction due to bacteria in silage going into eyes - problem from inside the eye = doesn’t show damage on fluorescein
CS of bovine iritis?
- Early cases = constricted pupils
- Patchy / multiple areas of corneal opacity
- Glaucoma
- White flocules in anterior chamber
- later = vascularisation
What is treatment of bovine iritis?
- Sub-conjunctival injection of
-atropine
-dexamethasone - +/-antibiotics
What animals get squamous cell carcinoma?
- Breed disposition = herefords
- Older animals (>5y/o)
- Related to UV exposure
What should be done with SCC?
- Invasive = involving = cornea, third eyelid, conjunctiva
- Surgical removal / enucleation
What are common foreign bodies of the eye?
What can it lead to?
- Grass seeds
- Straw
- Can lead to keratitis
What are secondary eye diseases?
- Malignant catarrhal fever
- IBR
- Listeriosis
- BVD
- Septicaemia
- Endotoxaemia
What is malignant catarrhal fever?
- Ovine herpes virus 2
- Invariably fatal
- can be transmitted from sheep or buffalo
What are clinical signs of malignant catarrhal fever?
- “head and eye form” most common
- Persistent pyrexia 41°C
- Depressed - encephalitis
- Nasal & mouth erosions
- lymph nodes enlarged
- Respiratory signs
- Diarrhoea
What are eye lesions in MCF?
- Conjunctivitis
- Eyelid oedema
- Blepharospasm
- Corneal opacity - centripetal
How is blue tongue differentiated from MCF?
- Blue tongue =
– inflammation of the mucous membranes, congestion, swelling and haemorrhages.
– No diarrhoea, corneal opacity or ulceration / erosion in nasal or oral cavity
– Sheep are generally the worst affected while cattle and goats do not usually show clinical signs
– can carry the virus for a period of time
What is IBR?
- Bovine herpes virus 1
- Latent carriers = trigeminal ganglion
-recrudescence = stress
What are clinical signs of IBR?
- Pyrexia 41oC
- Conjunctivitis & serous discharge
- Corneal oedema
- Nasal lesions & discharge
- Severe milk drop
What is listeriosis? CS? Tx?
- Infection to brain via trigeminal / facial nerve
- encephalitis
- Circling
- Unilateral facial paralysis
- Depressed
- Menace test = animal will move away but not blink
- Tx = oxytet or penicillin
What is seen with the eye in BVD?
- Cataracts
What is seen in the eye with septicaemia?
- Hypopyon
What causes sunken eyes?
- Dehydration
What causes blood in anterior chamber?
Bracken poisoning
What can cause blindness?
- CCN - cerebro-cortical necrosis - thiamine (vit B1) deficiency
- Lead poisoning
- Vitamin A deficiency
- Twin lamb disease - sheep only
What are signs of CCN?
- Early cases = star gazing
- -ve menace test = blind
- +ve pupillary response to light
- Nystagmus + convulsions
- Opisthotonus
What is treatment of CCN?
- IV thiamine every 3-4hrs
-vit B1 injection (Bimeda)
What is seen with lead poisoning? Tx? Dx?
- Any age - usually young cattle
- Batteries, lead paint …
- -ve menace test
- Dilated pupils
- Tremors + convulsions
- Tx = Sodium calcium edetate (EDTA) IV + sedation
-withdrawal period on meat / milk - Dx = lead in kidneys + history
What is seen with vitamin A deficiency?
- Growing cattle indoors
- Roots + straw diet
- Night blindness
- -ve menace response
- Dilated pupils
- Oedema of optic disk
