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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
small ruminants MYCOPLASMA KERATOCONJUNCTIVITIS * agent * clinical signs
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
small ruminants MYCOPLASMA KERATOCONJUNCTIVITIS * diagnosis and treatment
similar to Chlamydia • Mild cases self-limiting • Treatment can shorten course
27
small ruminants PARASITIC KERATOCONJUNCTIVITIS
* 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
small ruminants RETINAL DEGENERATION
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
small ruminants RETROBULBAR DISEASE
* Retrobulbar abscess after disbudding * Placement of temporary tarsorrhaphy * decrease corneal exposure secondary to exophthalmos
30
small ruminants CENTRAL/CORTICAL BLINDNESS
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
small ruminants OCULAR MANIFESTATION OF SYSTEMIC DISEASE **Tetanus (Clostridium tetani)**
* 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
small ruminants OCULAR MANIFESTATION OF SYSTEMIC DISEASE **Botulism (Clostridium botulinum)**
* Toxin prevents release of acetylcholine → irreversibly inhibits neurotransmission → flaccid paralysis * **Mydriasis (dilated pupils), decreased or absent PLRs, ascending limb paresis, excessive salivation, death**
33
small ruminants OCULAR MANIFESTATION OF SYSTEMIC DISEASE **Listeriosis (Listeria monocytogenes)**
* 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
camelids CONGENITAL ABNORMALITIES
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
camelids CORNEAL DISEASE **Corneal ulceration**
**• Most common ocular disease of New World camelids** • Likely traumatic cause • Treat like horses
36
Camelids CORNEAL DISEASE * Corneal abscess * Superficial dendritic ulcers
Corneal abscess • Bacterial \> fungal • Resolve faster than horses Superficial dendritic ulcers • Possible viral origin (EHV-1) • Responsive to cidofovir
37
camelids CORNEAL DISEASE **• Infected corneal ulcers**
* Infected corneal ulcers - diagnose and manage * similar to companion animals * Medical – subpalpebral lavage line * Surgical – conjunctival pedicle graft
38
Swine Microphthalmos
* Maternal vitamin A deficiency * Skeletal and CNS anomalies * Congenital in Yorkshire pigs * autosomal recessive
39
Swine Keratoconjunctivitis
* Mycoplasma sp. * Chlamydia sp. * Pseudorabies * reproductive and respiratory disease; fatal * Hog cholera * anterior and posterior uveitis; high mortality
40
SWINE: CATARACTS
* Congenital (Yucatan micropigs) * Inherited juvenile (pot-bellied pigs) * Hygromycin B (an antibiotic) * Dose-dependent, may be cumulative * Riboflavin deficiency
41
swine “FAT BLINDNESS”
**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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