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NEU2 > Large animal ophthalmology > Flashcards

Large animal ophthalmology Flashcards

1
Q

What do sunken eyes commonly indicate in large animals?

A

Dehydration

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2
Q

What effect do toxicity or septicaemia commonly have on the eyes?

A

Lead to congestion of mucous membranes, including the conjunctiva

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3
Q

What can be assessed in aqueous/vitreous samples of the eye?

A
  • Calcium or magnesium in cases of sudden death
  • Urea
  • Beta hydroxybutyrate
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4
Q

What is meant by blaines in large animals and what does this suggest?

A

Swelling of the eyelids, hives/pohtosensitisation as an allergic reaction

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5
Q

Briefly outline besnoitiosis

A
  • Protozoal parasite with severe effect on skin

- Very pathognomic lesions in the eye, almost cyst like appearance without conjunctival inflammation

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6
Q

List the ophthalmic conditions commonly affecting cattle

A
  • New Forest eye (IBK)
  • Silage eye (bovine iritis)
  • Squamous cell carcinoma
  • Systemic viral infections e.g. IBR ad MCF
  • BVS/catarats
  • Hypovitaminosis A
  • Ringworm
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7
Q

List diseases of young stock/calves that may have ophthalmic presentations

A
  • Lead poisoning
  • Cerebrocortical necrosis
  • Meningitis
  • Listeriosis
  • Tetanus
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8
Q

What causes New Forest eye in cattle?

A
  • Aka infectious bovine keratoconjunctivitis

- Moraxella bovis G-ve aerobic bacterium

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9
Q

Describe the clinical signs of New Forest eye

A
  • Seen in group setting, young stock at pasture, transmission by flies in summer
  • Severe pathology in cornea, blood vessel infiltration, opacity
  • Significant pain
  • May get perforation of cornea
  • Old lesions may be visible as pigmented scars
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10
Q

Describe the treatment of infectious bovine keratoconjunctivitis

A
  • Topical cloxacillin ointment (impractical,, stressful)
  • Tetracycline (often get secondary Mycoplasma infection)
  • Bulbar conjunctivitis injection as depot source, IM can also be used
  • NSAIDs
  • Suture eyelids to control pain and reduce risk of performation
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11
Q

Why should topical steroids not be used in the treatment of IBK?

A

Risk of ulceration

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12
Q

Outline the prevention of IBK

A
  • Fly control and pasture control

- Some age related immunity so do not mix stock of different ages

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13
Q

What is iritis?

A

Inflammation of the iris

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14
Q

Describe the clinical signs of iritis in cattle

A
  • Severe intraocular inflammation without systemic illness
  • Blindness
  • Yellow cornea
  • Fibrin and collagen accumulations in anterior chamber and cornea
  • Signs of anterior inflammation
  • May see foreign body in some cases, or evidence of physical trauma
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15
Q

Outline the cause of silage eye in cattle

A
  • Is iritis
  • Pathogenesis poorly understood
  • Some association with Listeria
  • May be a contaminant of silage and poor silage handling
  • To prevent, consider feeding method
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16
Q

Outline the treatment of silage eye in cattle

A
  • Usually just steroids rather than antibiotics
  • If just silage eye, then only nneed anti-inflamma
  • Bulbar subconjunctival injection to act as depot
17
Q

What is ocular squamous cell carcinoma commonly known as?

A

Cancer eye

18
Q

Describe the appearance of ocular squamous cell carcinoma in cattle

A
  • Ocular surface
  • small mass, typically affects eye ball at limbus
  • Looks like wart-like mass
  • Can affect eyelid and third eyelid, usually lighter coloured skin
  • Some may bleed
19
Q

Outline the treatment of ocular squamous cell carcinomas in catle

A
  • Depends on extent, may require enucleation if globe is not salvageable or if orbit is affected
  • Enucleation can be performed standing
  • Or under local, can clamp and remove mass
20
Q

How does IBR cause ocular disease in cattle

A
  • Infectious bovine rhinotracheitis, BHV-1
  • Affects upper resp. tract and eyes
  • Eye and mucous membranes around there are sites of viral replication and damage
21
Q

Describe the ocular signs of IBR

A
  • Conjunctivitis (hyperaemia and chemosis)
  • Bilateral serous ovular discharge
  • Diffuse corneal oedema possible
  • In immunological naiive first signs maybe pyrexia and conjunctivitis
  • Secondary bacterial infection leading to purulent discharge and ulceration
  • Can be fatal
22
Q

Describe the appearance of the respiratory tract with IBR

A

Ulceration in upper and lower resp. tract

23
Q

What are the causative agents of malignant catarrhal fever?

A

Rhadinovirus genus of Gammaherpesviridae subfamily of Herpesviridae

24
Q

Outline the pathogenesis of MCF

A

Lymphotrophic herpesviruses that are commonly associated with lymphoproliferation

25
Q

Outline the clinical signs of MCF

A
  • Single animals, mixed with sheep
  • Tends to present as individual animals
  • High mortality in cows
  • Fever 104-107F
  • Nasal and ocular discharge
  • Enlarged lymph nodes
  • Uveitis
  • Occasionally CNS signs
  • More systemic vs IBR, pathology similar to vasculitis
26
Q

What is the source of MCF?

A

Ovine herpes virus, cow is end host, infected by sheep virus

27
Q

What is the cause of cerebrocortical necrosis in cattle?

A

Thiamine deficiency, multifocal abscesses of brain

28
Q

Describe the clinical signs of cerebrocortical necrosis

A
  • Present with circling

- Usually young animals put onto concentrates

29
Q

How is cerebrocortical necrosis diagnosed?

A

Administration of feed/supplements with B vitamins

30
Q

Discuss the possible causes of congenital cataracts in cattle

A
  • Difficult to prove
  • may be assocaited with BVDV
  • May be inherited
31
Q

Describe the appearance of hypovitaminosis A in cattle

A
  • Excitable animals
  • Pale optic nerve
  • Blindness
  • Papilloedema
32
Q

List common ocular conditions affecting sheep

A
  • Pink eye
  • Orf
  • Bright blindness
  • Pregnancy toxaemia
  • Gid
  • Entropion in lambs
33
Q

Describe pink eye in sheep (cause, occurrence, spread)

A
  • Corneal infection of sheep
  • Commonly when closely housed and in winter
  • Chlamydia and mycoplasma implicated
  • Similar to New forest disease
  • Young animals, spread by contact
  • Very severe
34
Q

Describe the ocular signs of orf

A
  • Periocular irritation
  • Scabbing
  • Thickening of eyelid

NEU2 (23 decks)

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