Bovine Eye Flashcards
Give 3 primary diseases of the eye
New forest disease (infectious bovine kerato-conjunctivitis, ‘pink eye’)
Bovine iritis (silage eye)
Squamous cell carcinoma (cancer eye)
What causes New Forest Disease (infectious bovine kerato-conjunctivitis)?
Morexella bovis (gram -ve, transmitted by flies)
Also:
-Mycoplasma spp
-Pneumonia viruses etc
What is blepharospasm?
Abnormal contraction/twitch of eyelid
Give some clinical signs of New Forest Eye
Lacrimation
Blepharospasm
Early keratosis-white spot
Ulcer exposing Descemets membrane (could rupture -> remove eye), pannus
Healing ulcer -vascularisation, may have permanent scarring
How do you treat New Forest Eye?
LA eye ointment (cloxacillin)
Sub-conjunctival injection (ampicillin, amoxycillin, oxytetracycline etc, best on bulbar conjunctiva) (oxytet can be irritant so dilute with water)
Suture 3rd eyelid & eyelids or eyelids only
Eye patches
Give some risk factors for New Forest Eye
Flies (transmit moraxella) Woodland Dust Chaff UV light (all of the above irritate the eye) 'Virus pneumonia'
Which season are you most likely to see New Forest Eye?
Summer (flies)
How can you prevent New Forest Eye?
Fly control- ear tags, pour ons, permethrins
Graze away from fly habitat (woodland)
Ventilation and fly control inside buildings
Vaccine-USA
What is Bovine Iritis associated with?
Big bale silage feeding
Which season is Bovine Iritis seen in?
Winter
Give the clinical signs of Bovine Iritis
Early cases: constricted pupil
Patchy/multiple areas of corneal opacity
Glaucoma
White flocules in anterior chamber
Later: vascularisation (inside surface of cornea)
Negative to fluorescein staining cf New Forest Disease
Eye may bulge, may get secondary keratitis
Bovine Iritis is a disease of which part of the eye?
Intenal cornea
Give some causes of Bovine Iritis
Unknown
Hypersensitivity reaction?
Link with Listeria?
Form of uveitis
How do you treat Bovine Iritis?
Antibiotics are ineffective
Sub-conjunctival (bulbar) injection of:
-Atropine (5mg) to dilate the pupil
-With dexamethasone (1-3mg) steroid
What size needle would you use for a sub-bulbar conjunctival injection?
22G (pale blue)
Use LA first
Hold head up and rotate for easy access
Which breed is predisposed to squamous cell carcinoma?
Herefords (white-faced)
When suturing eyelids together, what should you not do?
Suture through the conjunctiva- irritant
Give some risk factors for squamous cell carcinoma
White faces
>5 years old
UV exposure (Tropics)
Which parts of the eye does squamous cell carcinoma affect?
Cornea (can be invasive)
3rd eyelid
Conjunctiva
How do you treat squamous cell carcinoma?
Can remove but may recur
What can a foreign body in the eye lead to?
Keratitis
What is keratitis?
Inflammation of the cornea
What causes Malignant Catarrhal Fever?
Ovine herpes virus 2 (doesn’t cause clinical disease in sheep)
What is the prognosis for Malignant Catarrhal Fever?
Usually fatal
Give the clinical signs of Malignant Catarrhal Fever
‘Head and eye form’ most common
- Persistent pyrexia (41oC)
- Depressed-encephalitis
- Nasal and mouth erosions
- Enlarged lymph nodes
- Respiratory signs
- Diarrhoea
How can you diagnose Malignant Catarrhal Fever?
ELISA
Give the secondary eye lesions seen with Malignant Catarrhal Fever
- Conjuntivitis
- Eyelid oedema
- Blepharospasm
- Corneal opacity
When are herpes viruses typically secreted?
During times of stress (lie latent in trigeminal ganglion)
How do you diagnose infectious bovine rhinotracheitis (BHV 1)?
ELISA
How do you prevent infectious bovine rhinotracheitis (BHV 1)?
Intra-nasal vaccines
Give the clinical signs of infectious bovine rhinotracheitis (BHV 1)?
Pyrexia (41oC)
Conjunctivitis and serous discharge (red eye)
Corneal oedema
Nasal lesions & discharge
How does listeriosis infect cows?
Infection via CNV or VII to brain via teeth
Give the clinical signs of listeriosis
- Septicaemia form in sheep -> die
- Encephalitis more common (micro-abscesses in brain)
- Circling disease, unilateral facial paralysis (droopy ear), depressed, positive reaction to menace test as can still see but can’t feel face if you poke with needle
- Facial paralysis -> dry eye keratosis
How do you treat dry eye keratosis?
High doses of penicillin or oxytetracycline
Give some generalised diseases in which eye lesions may feature
- BVD-cataracts, micropthalmia (infection between day 120-150 of pregnancy)
- Septicaemia-hypopyon (pus in eye, calves), petechiae
- Endotoxaemia-injected conjunctiva, petechiae
- Dehydration-sunken eye
Poisoning with what can result in blood in the anterior chamber (hyphaema)?
Bracken
Which conditions can cause blindness?
- Cerebro cortical necrosis
- Lead poisoning
- Vit A deficiency
- Twin lamb disease (sheep)
Cerebro-cortical necrosis is seen in which cattle?
Young growing cattle
Thiaminase production in rumen (ie lack of thiamine)
High energy diet
How do you diagnose cerebro-cortical necrosis?
PM (brain changes, parts of brain fluoresce under UV light)
How do you treat cerebro-cortical necrosis?
IV thiamine (vitamin B1) every 4 hours (inject slowly)
What are the clinical signs of cerebro-cortical necrosis?
- Star-gazing (early cases)
- Negative menace response (blind)
- Positive pupillary response to light
- Nystagmus and convulsions
- Opistothonus
Give the clinical signs of lead poisoning
- Negative menace test (blind)
- Dilated pupils
- Tremors and convulsions
How do you treat lead poisoning?
Calcium versenate (chelating agent) iv and sedation
How do you diagnose lead poisoning?
Pb in kidney, history
Vitamin A deficiency typically affects which cows?
Growing cattle kept indoors
Fed root and straw diet
Give the clinical signs of Vitamin A deficiency
- Night blindness
- Negative menace test
- Dilated pupils
- Oedema of optic disk
- Can also have skeletal abnormalities
