Farm opthamology

Question 1

what conditions affect the cow eye?

Answer 1

• Trauma
• Infectious Bovine Keratoconjunctivitis (IBK)/”Pink eye”
• Bovine iritis /“Silage eye”
• Squamous cell carcinoma (SCC)
• Infectious Bovine Rhinotracheitis (IBR)
• Malignant catarrhal fever (MCF)
• Cataracts
• Hypovitaminosis A

Question 2

what is tarsorrhaphy?

Answer 2

stitching the eyelid together

Question 3

summaries Infectious bovine keratoconjunctivitis (IBK)

Answer 3

• “New Forest Eye”, “Pink eye”
  Moraxella bovis, Gram-negative, aerobic bacterium
• flys transmit, Musca autumnalis
• • Carrier remains afterwards (main source infection)
• Clinical presentation - Ulcerative keratoconjunctivitis: blepharospasm, epiphora, corneal oedema, deep ulceration, neovascularisation, Painful
• Treatment: Topical Cloxacillin ointment, Tetracycline (if you have 2º mycoplasma spp)

Question 4

summaries bovine iritis

Answer 4

silage eye
Listeria infection and associated immune response
- Pathogenesis
* Initial stage: marked lachrymation blepharospasm
* Later stages: severe inflammatory changes, including iris folding and the development of a bluish opacity in the cornea
* Focal fibrin aggregations in the anterior chamber

clinical presentation: * Often unilateral
* Corneal oedema +/ vascularisation
treatment: * Anti-inflammatories, Topical cloxacillin or Subconjunctival oxytetracycline

Question 5

summarise Ocular Squamous cell carcinoma (OSCC)

Answer 5

Ocular Squamous cell carcinoma (OSCC) - “Cancer eye”
Aetiology
* Carcinoma tumour
* Breed: Hereford
* Age related
* Exposure to sunlight

Pathogenesis
Initially benign…later stages malignant
Plaque>Papilloma>Non-invasive carcinoma>Invasive carcinoma

presentation:
Limbal grey-white plaque (horizontal), Ulcerative lesion, Metastasis

can attempt surgical excision but enuclation is probably easier

Question 6

what conditions affect the sheep eye

Answer 6

• Infectious Keratoconjunctivitis “pink eye”
• Listeria
• Entropion in lambs

Question 7

what two cattle respiratory diseases affect the cow eye? summaries them

Answer 7

Infectious bovine rhinotracheitis (IBR)
Clinical presentation
* Affects upper respiratory tract and eyes
* Conjunctivitis: Hyperaemia and chemosis (oedema)
* Bilateral serous/mucopurulent ocular discharge
* Diffuse corneal oedema, ulceration
* White plaques (0.2/0.5mm ⌀) 1-2 week after onset
* viral so not normally antibiotics

Malignant catarrhal fever (MCF)
Clinical presentation
* Photophobia
* Nasal & ocular discharge
* Uveitis: red eyes, corneal oedema, hypopyon, miosis, iris swelling
* Progression of corneal oedema and uveitis is associated with poor prognosis
* Occasionally CNS signs (encephalitis)

Question 8

what are the common causes of bovine cateracts?

Answer 8

• Inherited
• BVD
• Schmallenberg
• Neospora
• Toxoplasma
• Vitamin A deficiency

Question 10

summaries the nutritional syndrome that causes ocular issues in cattle

Answer 10

Hypervitamionosis A
Vitamin A is synthesized in the liver and intestinal mucosa (plant carotenoid precursors)

More common in growing ruminants

Blindness, nystagmus, lack of pupillary reflex, seizure, cataract

Retinal degeneration and constriction of cranial nerve II

Question 11

what a the other causes of occular issues in cows?

Answer 11

photosensitivity - swollen face and occationally inflammation of the conjunctiva

Bluetongue - Primarily disease of sheep
Clinical signs
* Pyrexia
* Ocular and nasal discharge
* Conjunctivitis
* Swelling of head and neck
* Lameness

Besnoitiosis - characteristic nodules in the sclera

Question 12

summaries the ocular affects of Listerior of sheep

Answer 12

Anterior uveitis
* Pathongesis ,Clinical signs and diagnosis See Bovine iritis”
* Treatment: antibiotic and NSAID

Question 13

summaries Infectious keratoconjunctivitis of cattle

Answer 13

• Associated with Mycoplasma conjunctivae Also, Chlamydophila psitacci
• Close contact spread- direct contact
  **Initial ocular signs **
• Epiphora
• Conjunctival hyperemia
• Chemosis (swelling conjunctiva)
  As the infection progresses:
• Ocular discharge muco-purulent
• Inflammation spreads from the sclera to the cornea.
• Corneal neovascularisation
• Corneal ulceration

Clinical presentation
Ocular discomfort and discharge
Marked conjunctivitis
Cloudy ocular surface
Corneal ulceration
Temporary blindness

Treatment
Sub-conjunctival antibiotic - going out of fashion
Management changes

Prevention
Provide shelter outdoors
Provide adequate trough space
Quarantine new animals