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Ophthalmology Rotation > Small Ruminant & Swine Ophthalmology > Flashcards

Small Ruminant & Swine Ophthalmology Flashcards

1
Q
A
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2
Q

ANATOMIC VARIATIONS

  • Ruminants & camelids
  • Camelids
  • Swine
A
  • Ruminants & camelids
    • Horizontal pupil (pic)
  • Camelids
    • Dorsal & ventral pupillary ruff
  • Swine
    • Round pupil
    • Upper lacrimal punctum only
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3
Q

Vascularization

A

all around (not just half like SA)

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4
Q

Small Ruminants

CONGENITAL ABNORMALITIES
Microphthalmia

A
  • +/- microphakia, cataract, anterior segment dysgenesis, PPMs
  • Autosomal recessive in Texel sheep
  • Maternal infection with Bluetongue virus
  • Sulfur or selenium toxicity during gestation
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5
Q

small ruminants

CONGENITAL ABNORMALITIES

  • Hydrocephalus
  • Albinism
A

Hydrocephalus (pic)
• Blindness due to compression of optic nerve
• May have papilledema

Albinism
• Very rare (autosomal recessive in sheep)
• Pink iris, photophobia, nystagmus

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6
Q

Small ruminants

TERATOGENS: VERATRUM CALIFORNICUM

A
  • Veratrum californicum
  • Aka skunk cabbage, cow cabbage, western hellebore, California false hellebore, corn lily, and wild corn
  • Teratogenic component: multiple alkaloids
  • Roots >>> stems and leaves
  • Sheep > goats
  • Globe abnormalities when consumed on day 14 of gestation
  • Anophthalmia (no globe)
  • Synophthalmia (combined globes)
  • Cyclopia (one globe)
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7
Q

Small Ruminants

TERATOGENS: BLUETONGUE VIRUS

A
  • Transmission: Culicoides spp. (non-contagious)
  • Fever, abortion, facial edema, excessive salivation, mucous membrane erosion, pulmonary edema, sudden death
  • Ocular clinical signs (sheep):
    • Microphthalmia, retinal dysplasia +/- blindness
    • MLV at 8-11th wk of gestation → necrosis of developing retina
    • Blepharitis & conjunctivitis in adult sheep
  • Prevention: Modified-live vaccine available in USA, midge control, environmental management
  • Treatment: Symptomatic and supportive care
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8
Q

Small Ruminants

ENTROPION

A
  • Inversion of the eyelid
  • Leads to squinting and tearing
  • Can lead to corneal ulceration
  • More commonly affects the lower eyelid
  • Common in lambs
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9
Q

Small Ruminants

ENTROPION

primary vs secondary

A
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10
Q

Small Ruminants

ENTROPION TREATMENT

temporary

A

Temporary eyelid eversion
• Tacking sutures
• Metal clips or skin staples
• Eyelid irritant injection
• Antibiotic (e.g. penicillin)
• Liquid paraffin

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11
Q

Small Ruminants

ENTROPION TREATMENT
Permanent correction

A
  • Hotz-Celsus
  • Permanent correction in skeletally mature animals
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12
Q

small ruminants

BLEPHARITIS

causes

A

Infectious
• Parasitic
• Bacterial
• Fungal
• Viral

Non-infectious
• Sunburn
• Photosensitization

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13
Q

small ruminants

BLEPHARITIS: PARASITIC

A
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14
Q

small ruminants

BLEPHARITIS: BACTERIAL

A
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15
Q

small ruminants

BLEPHARITIS: FUNGAL
Dermatophytosis

A

• Goats more commonly affected than sheep
• Trichophyton sp and Microsporum sp
• ZOONOTIC & CONTAGIOUS
• Clinical signs: dry/crusty periocular alopecia that is often non-pruritic
• Self-limiting disease (eliminated in 4-5 weeks)

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16
Q

small ruminants

BLEPHARITIS: VIRAL

  • capripoxvirus
  • papillomatosis
A

Capripoxvirus
• Sheep/goatpox
• Foreign animal disease: REPORTABLE
• Respiratory spread or through skin through abrasions
• Circular lesions of eyelid → firm papules → necrosis
• Up to 100% morbidity and mortality in unexposed populations

Papillomatosis
• Eyelid of sheep; young animals
• Usually self-limiting, not pruitic

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17
Q

small ruminants

BLEPHARITIS: VIRAL

  • Parapoxvirus
  • Bluetongue virus
A

Parapoxvirus
• Contagious ecthyma (“Orf or sore mouth”)
• Highly contagious (direct contact, fomites)
• Painful; crusts along mucous membranes

Bluetongue virus
• Orbivirus
• Conjunctivitis and blepharitis in sheep

18
Q

small ruminants

BLEPHARITIS: NONINFECTIOUS

A
  • Sunburn (less common)
  • Photosensitization
    • Primary = photoreactive substances
      • Plants
      • Some medications
    • Secondary = toxic liver damage → inability to excrete phylloerythrin
      • More common
    • Clinical signs
    • Pruritic!!! = self-trauma
    • Facial, eyelid, and lower limb edema
    • Necrosis of ear tips
19
Q

small ruminants

CONJUNCTIVA AND CORNEA

  • what can be wrong in appearance
A
  • Chemosis
    • Hypoproteinemia
  • Conjunctival petechiation
  • Color
    • Icterus, palor
20
Q

Why might you do this?

A

FAMACHA SCORING FOR HAEMONCHUS CONTORTUS

21
Q

small ruminants

KERATOCONJUNCTIVITIS

A

Serious economic concern

  • Bacterial
    • Chlamydia sp., Mycoplasma sp.
  • Parasitic
    • Oestrus ovis, Thelazia sp.
  • Environmental factors (e.g. dust/pollen/fumes), mechanical irritation, foreign bodies, etc.
22
Q

small ruminants

CHLAMYDIA KERATOCONJUNCTIVITIS

  • agent
  • properties
  • where in body
  • transmission
  • risk factors
A

Chlamydia pecorum

  • Gram negative obligate intracellular bacteria
  • Present in bodily secretions
    • Tears, nasal secretions, urine, feces
  • Contagious via direct transmission
    • Feed bunkers, poor ventilation, overcrowding, dry/dusty conditions
  • Exacerbated following stress (lambing or kidding season)
23
Q

small ruminants

CHLAMYDIA KERATOCONJUNCTIVITIS

  • signalment
  • clinical signs
A
  • Signalment:
    • Up to 6 months of age
    • More common in lambs than kids
  • Clinical signs:
    • Blepharospasm
    • Conjunctivitis
    • Mucopurulent discharge
    • Corneal vascularization & edema
    • Corneal ulceration
    • Polyarthritis (sheep only)
24
Q

small ruminants

CHLAMYDIA KERATOCONJUNCTIVITIS

  • diagnosis
  • treatment
  • prevention
A
  • Diagnosis:
    • Clinical presentation
    • PCR (preferred method)
    • Conjunctival cytology (intracytoplasmic inclusion bodies)
    • Culture (false negatives late in disease)
  • Treatment:
    • Single injection of oxytetracycline (LA-200, BioMycin, etc.) or multiple injections of Tylosin
    • Flunixin meglumine
    • Terramycin® ophthalmic ointment
  • Prevention:
    • quarantine sick animals and isolate new stock (reinfection possible)
25
Q

small ruminants

MYCOPLASMA KERATOCONJUNCTIVITIS

  • agent
  • clinical signs
A

M. conjunctivae var capri & M. mycoides var ovis
• More common in goats

Clinical signs:
• Blepharospasm, conjunctivitis, corneal vascularization
• Corneal opacification and blindness (goat)
• Corneal ulceration and mucopurulent discharge (sheep)
• Concurrent arthritis, pleuropneumonia, and/or mastitis

26
Q

small ruminants

MYCOPLASMA KERATOCONJUNCTIVITIS

  • diagnosis and treatment
A

similar to Chlamydia
• Mild cases self-limiting
• Treatment can shorten course

27
Q

small ruminants

PARASITIC KERATOCONJUNCTIVITIS

A
  • Oestrus ovis (nasal bots; sheep bot fly)
    • Larvae invade the ocular mucous membranes, migrate to nasolacrimal duct & eye
    • Large spiny larvae are large (~2.5cm) cause irritation & secondary infection
  • Treatment:
    • Removal of larvae
    • Ivomec® sheep drench
    • Best to treat in autumn
28
Q

small ruminants

RETINAL DEGENERATION

A

Usually acquired in livestock animals

  • Plant toxicities
    • Bracken fern (Pteridium aquilinum)
    • Blind grass (Stypandra glauca)
    • Locoweed (Astragalus and Oxytropus sp.)
  • Vitamin A deficiency
    • Persistent deficiency leads to retinal degeneration
    • Night blindness, corneal ulcers
  • Scrapie
    • Transmissible spongiform encephalopathy
    • Prion disease
    • Pruritis, changes in mental status, abnormal stance
    • Normal ophthalmic reflexes, inconsistent menace
    • Multifocal, round tapetal lesions (subretinal lipid)
29
Q

small ruminants

RETROBULBAR DISEASE

A
  • Retrobulbar abscess after disbudding
  • Placement of temporary tarsorrhaphy
    • decrease corneal exposure secondary to exophthalmos
30
Q

small ruminants

CENTRAL/CORTICAL BLINDNESS

A

Vision loss in an otherwise normal eye → should have normal OCULAR reflexes

  • Polioencephalomalacia (PEM):
    • Thiamine deficiency
    • Sulfur toxicosis
  • Taenia multiceps (larval migration)
  • Listeria monocytogenes infection
  • Hydrocephalus
  • Scrapie (other neurologic signs predominate)
  • Toxins: lead, arsenic, and brassica ingestion
31
Q

small ruminants

OCULAR MANIFESTATION OF SYSTEMIC DISEASE
Tetanus (Clostridium tetani)

A
  • Toxin prevents inhibitory signal transduction to motor neurons → disinhibition of lower motor neurons → stiffness and spasticity
  • Sawhorse stance, retraction of lips/ears, elevation of tail, retraction of globe and prolapse of third eyelids, bloat, death
32
Q

small ruminants

OCULAR MANIFESTATION OF SYSTEMIC DISEASE
Botulism (Clostridium botulinum)

A
  • Toxin prevents release of acetylcholine → irreversibly inhibits neurotransmission → flaccid paralysis
  • Mydriasis (dilated pupils), decreased or absent PLRs, ascending limb paresis, excessive salivation, death
33
Q

small ruminants

OCULAR MANIFESTATION OF SYSTEMIC DISEASE
Listeriosis (Listeria monocytogenes)

A
  • Spoiled or incompletely fermented silage or corn
  • Gram + facultative anaerobic bacterium
  • Systemic clinical signs: abortion, meningitis, encephalitis, septicemia, death
  • Facial nerve paralysis, dry eye disease, corneal ulcers, nystagmus, strabismus, abnormal ocular reflexes, and blindness
34
Q

camelids

CONGENITAL ABNORMALITIES

A

Nasolacrimal defects
• “Wet face”, mucopurulent discharge, facial dermatitis
• More common in alpacas than llamas

Treatment:
• Incise the mucous membrane & cover the opening
• Cannulation of NLD
• Keep tubing in place for >6 weeks

35
Q

camelids

CORNEAL DISEASE
Corneal ulceration

A

• Most common ocular disease of New World camelids
• Likely traumatic cause
• Treat like horses

36
Q

Camelids

CORNEAL DISEASE

  • Corneal abscess
  • Superficial dendritic ulcers
A

Corneal abscess
• Bacterial > fungal
• Resolve faster than horses

Superficial dendritic ulcers
• Possible viral origin (EHV-1)
• Responsive to cidofovir

37
Q

camelids

CORNEAL DISEASE
• Infected corneal ulcers

A
  • Infected corneal ulcers - diagnose and manage
    • similar to companion animals
  • Medical – subpalpebral lavage line
  • Surgical – conjunctival pedicle graft
38
Q

Swine

Microphthalmos

A
  • Maternal vitamin A deficiency
  • Skeletal and CNS anomalies
  • Congenital in Yorkshire pigs
  • autosomal recessive
39
Q

Swine

Keratoconjunctivitis

A
  • Mycoplasma sp.
  • Chlamydia sp.
  • Pseudorabies
    • reproductive and respiratory disease; fatal
  • Hog cholera
    • anterior and posterior uveitis; high mortality
40
Q

SWINE: CATARACTS

A
  • Congenital (Yucatan micropigs)
  • Inherited juvenile (pot-bellied pigs)
  • Hygromycin B (an antibiotic)
  • Dose-dependent, may be cumulative
  • Riboflavin deficiency
41
Q

swine

“FAT BLINDNESS”

A

Entropion in pot-bellied pigs
• Subcutaneous fat on forehead/periocular region
• Surgical correction usually needed
• Post-operative weight control

Ophthalmology Rotation (20 decks)

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