Small Ruminant & Swine Ophthalmology Flashcards
ANATOMIC VARIATIONS
- Ruminants & camelids
- Camelids
- Swine
- Ruminants & camelids
- Horizontal pupil (pic)
- Camelids
- Dorsal & ventral pupillary ruff
- Swine
- Round pupil
- Upper lacrimal punctum only
Vascularization
all around (not just half like SA)
Small Ruminants
CONGENITAL ABNORMALITIES
Microphthalmia
- +/- microphakia, cataract, anterior segment dysgenesis, PPMs
- Autosomal recessive in Texel sheep
- Maternal infection with Bluetongue virus
- Sulfur or selenium toxicity during gestation
small ruminants
CONGENITAL ABNORMALITIES
- Hydrocephalus
- Albinism
Hydrocephalus (pic)
• Blindness due to compression of optic nerve
• May have papilledema
Albinism
• Very rare (autosomal recessive in sheep)
• Pink iris, photophobia, nystagmus
Small ruminants
TERATOGENS: VERATRUM CALIFORNICUM
- 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)
Small Ruminants
TERATOGENS: BLUETONGUE VIRUS
- 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
Small Ruminants
ENTROPION
- Inversion of the eyelid
- Leads to squinting and tearing
- Can lead to corneal ulceration
- More commonly affects the lower eyelid
- Common in lambs
Small Ruminants
ENTROPION
primary vs secondary
Small Ruminants
ENTROPION TREATMENT
temporary
Temporary eyelid eversion
• Tacking sutures
• Metal clips or skin staples
• Eyelid irritant injection
• Antibiotic (e.g. penicillin)
• Liquid paraffin
Small Ruminants
ENTROPION TREATMENT
Permanent correction
- Hotz-Celsus
- Permanent correction in skeletally mature animals
small ruminants
BLEPHARITIS
causes
Infectious
• Parasitic
• Bacterial
• Fungal
• Viral
Non-infectious
• Sunburn
• Photosensitization
small ruminants
BLEPHARITIS: PARASITIC
small ruminants
BLEPHARITIS: BACTERIAL
small ruminants
BLEPHARITIS: FUNGAL
Dermatophytosis
• 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)
small ruminants
BLEPHARITIS: VIRAL
- capripoxvirus
- papillomatosis
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
small ruminants
BLEPHARITIS: VIRAL
- Parapoxvirus
- Bluetongue virus
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
small ruminants
BLEPHARITIS: NONINFECTIOUS
- 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
-
Primary = photoreactive substances
small ruminants
CONJUNCTIVA AND CORNEA
- what can be wrong in appearance
- Chemosis
- Hypoproteinemia
- Conjunctival petechiation
- Color
- Icterus, palor
Why might you do this?
FAMACHA SCORING FOR HAEMONCHUS CONTORTUS
small ruminants
KERATOCONJUNCTIVITIS
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.
small ruminants
CHLAMYDIA KERATOCONJUNCTIVITIS
- agent
- properties
- where in body
- transmission
- risk factors
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)
small ruminants
CHLAMYDIA KERATOCONJUNCTIVITIS
- signalment
- clinical signs
- 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)
small ruminants
CHLAMYDIA KERATOCONJUNCTIVITIS
- diagnosis
- treatment
- prevention
- 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)
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
small ruminants
MYCOPLASMA KERATOCONJUNCTIVITIS
- diagnosis and treatment
similar to Chlamydia
• Mild cases self-limiting
• Treatment can shorten course
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
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)
small ruminants
RETROBULBAR DISEASE
- Retrobulbar abscess after disbudding
- Placement of temporary tarsorrhaphy
- decrease corneal exposure secondary to exophthalmos
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
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
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
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
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
camelids
CORNEAL DISEASE
Corneal ulceration
• Most common ocular disease of New World camelids
• Likely traumatic cause
• Treat like horses
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
camelids
CORNEAL DISEASE
• Infected corneal ulcers
- Infected corneal ulcers - diagnose and manage
- similar to companion animals
- Medical – subpalpebral lavage line
- Surgical – conjunctival pedicle graft
Swine
Microphthalmos
- Maternal vitamin A deficiency
- Skeletal and CNS anomalies
- Congenital in Yorkshire pigs
- autosomal recessive
Swine
Keratoconjunctivitis
- Mycoplasma sp.
- Chlamydia sp.
- Pseudorabies
- reproductive and respiratory disease; fatal
- Hog cholera
- anterior and posterior uveitis; high mortality
SWINE: CATARACTS
- Congenital (Yucatan micropigs)
- Inherited juvenile (pot-bellied pigs)
- Hygromycin B (an antibiotic)
- Dose-dependent, may be cumulative
- Riboflavin deficiency
swine
“FAT BLINDNESS”
Entropion in pot-bellied pigs
• Subcutaneous fat on forehead/periocular region
• Surgical correction usually needed
• Post-operative weight control
