Ruminant Ophthalmology 2 Flashcards
Posterior Segment
Blindness
- what vitamin?
- pathogenesis, progression
- dx, tx
Vitamin A deficiency
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- Bone growth at optic foramen →
constriction of optic nerve
- Night blindness → day blindness
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Dx: serum levels < 25 mg/dl
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Tx: parenteral vitamin A supplementation
toxic plants in various species that affect the eye
Cattle
- Male Fern (Dryopteris filix mas)
* weakness
* malaise
* constipation
* optic nerve atrophy
* retinal degeneration
* hemorrhage on/around optic
disc papilledema
* Blind
* No antidote
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Sheep / Goat
- Bright Blindness (Bracken Fern (Pteridum aquilinum))
- Blind Grass (Stypandra glauca) “nodding blue lily” Australia
* ptaquiloside toxicity
* optic nerve atrophy, tapetal hyperreflectivity,
vascular attenuation
* sheep in parts of England and Wales
* permanently blind (alert attitude)
* bone marrow suppression, hemorrhage,
immune-suppression, urinary tract
neoplasia
* No antidote
Veratrum californicum in sheep effects
- toxic alkaloids → jervine and cyclopamine (teratogen)
- Sheep day 14 of gestation = gastrulation and formation of the neural plate, before separation of the
optic fields - day 11-13, or 15-16 = normal fetus or embryos that died on day 18-23 if ewes severely affected
- anophthalmia, cyclopia, and synophthalmia
1 ocular tumor in cattle
- significance?
- ocular lesions
- prevention
Squamous Cell Carcinoma
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Significant economic loss (carcass condemnation if more than eye involved/ decreased milk production)
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Benign lesion with potential to regress or progress to malignant with
mets to regional LN’s
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Hereford and Holstein: predilection, ? Inheritance?
* UV light and absence or periocular pigment are predisposing factors to
developing tumors
* 7-8 years old
* ? herpesvirus/papilloma virus involvement?
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Ocular lesions:
* Eyelid margin, palpebral conjunctival, third eyelid, limbus or cornea
* Lesions are usually broad based and vascular with an irregular cobble-stone appearance
* Rapidly growing lesions may also ulcerate and have necrotic tissue
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Prevention:
* Cull lines with increased susceptibility (lack of periocular pigment)
Squamous Cell Carcinoma of eye treatment
Treatment:
Surgical excision with large margins –
exenteration of orbital contents
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Adjunctive therapy
* Cryotherapy
* Hyperthermia
* Radiation
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Third eyelid removal
* Auriculopalpebral nerve block
* Topical anesthesia
* Clamp base of third eyelid
* Cut with scissors or scalpel blade
* Usually, no sutures required
Bovine papilloma virus (BPV 1 and 2)
- issues with eyes, treatment, prevention
Pedunculated with a cauliflower appearance
Margin of the third eyelid
Similar appearance to SCC
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Treatment:
* Surgical excision
* Tend not to recur
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Prevention:
* Clean fomites (halters, nose leads, grooming equipment, ear marking equipment, rubbing posts, fences, milking equipment).
Lymphoma (LSA) in cattle
- issue with eye
- dx, tx, prevention
Linked: bovine leukemia virus
* Approximately 5% of BLV positive cows develop LSA
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C/S:
* Retrobulbar mass
* Exophthalmia +/- strabismus
* Unilateral or bilateral
* Severe
> exposure keratitis
> visual impairment and blindness
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Dx: cytology/histopathology
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Tx: palliative TE flap
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Prevention:
* BLV testing
* Prompt isolation
* Control blood sucking insects
Ocular Diseases in Camelids (Camels, Ilamas Alpacas, Vicuñas, Guanacos.)
- most ocular disease related to what?
- bacteria?
- glaucoma etiology
- steroids
- tapetum?
- Most ocular diseases are related to trauma
- Pseudomonas spp in normal conjunctiva
- Glaucoma is either congenital or 2nd to uveitis
- Do not recommend topical steroids to pregnant animals
- Atapetal
Camelids
Nasolacrimal duct (NLD) disorders
- etiology
- cs, dx, tx
Etiology:
Congenital
* Atresia/agenesis of duct or puncta
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Acquired = dacryocystitis
* temporary plug of mucus
* swelling of the duct from inflammation.
* if prolonged → fibrosis and
permanent occlusion of the duct.
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C/S:
Epiphora
+/- conjunctivitis
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Dx:
Jones test
Dacryocystorhinogram
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Tx:
Flush duct is possible to remove debris +/- antibiotics
Create opening with incision through imperforated mucosa
* Leave tubing in for 6 weeks
camelids Exophthalmia considerations
Reported, BUT cautionary note:
- Male llamas that have been in an altercation with another male may appear to evert the lower eyelids, giving
the impression of exophthalmia.
= part of the pouting syndrome caused by constriction of
the facial muscles that puts tension on the lower eyelid
which in turn exposes the conjunctiva.
camelids conjuntivitis
- etiology, cs, tx
Etiology:
* Primary: chlamydia, parasites (Thelazia californiensis)
* Secondary: corneal ulceration/abscess,
foreign bodies, uveitis
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C/S:
* Conjunctival inflammation +/- chemosis
* +/- blepharitis
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Tx:
* Primary: culture the ocular discharge, conjunctival cytology
* Secondary: treat the underlying cause
> Thelazia – manually remove worms, control
face flies
> Topical tetracycline, erythromycin TID-QID
> Flunixin meglumine systemic if severe
camelids
Corneal Ulceration (fluorescein stain positive)
Corneal Ulceration (fluorescein stain positive)
* Anterior stromal exposure
* Similar to other species: simple, indolent, complex
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Tx:
* Topical antibiotics in all cases
* Topical atropine if miosis
* Debride +/- grid keratotomy if indolent
* Serum if melting
* Systemic flunixin if uveitis
camelids
Corneal Stromal Abscess (+/- fluorescein stain)
Corneal Stromal Abscess (+/- fluorescein stain)
* White-yellow area within corneal stroma
* Bacterial or fungal
Tx:
* Topical bactericidal antibiotics
* Topical anti-fungal
> if no response
> if seen deep within corneal stroma
camelid cataract
- etiology
- c/s
- tx
= opacity of the lens
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Etiology: congenital, developmental, acquired
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C/S:
* White opacity of varying size within pupillary space
* +/- visual impairment
* +/- lens-induced uveitis
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Tx:
* Topical NSAID/corticosteroid (unless pregnant) BID-QID
* Cataract surgery (referral)
camelid Uveitis
- primary, secondary, work up, tx
Primary
* Septicemia
* EHV-1, Toxoplasmosis,
Aspergillosis
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Secondary
* Corneal ulcer, cataract
(lens-induced uveitis)
* Trauma (blunt/penetrating)
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Work-up
* PE, blood tests
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Anti-inflammatory therapy (no steroids if pregnant)
