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`What cranial nerves are required for positive menace response?
- afferent = optic (2)
- efferent = facial (7)
what cranial nerves are required for positive pupillary light reflex?
- afferent = optic (2)
- efferent = oculomotor (3)
- *remember its slower in FA
What cranial nerves are required for positive palpebral reflex? What about corneal reflex?
- afferent = trigeminal (5)
- efferent = facial (7)
- same for corneal, reserved for confirming euthanasia
what cranial nerves are needed to move globe in various directions?
3,4, 6 (oculomotor, trochlear, abducens)
what bovine virus can result in exophthalmos? What are two conditions that can result in enophthalmos?
- bovine leukemia virus (BLV)
- enophthalmos from dehydration and rapid fat loss
what species is more likely to have problems with entropion? at what age? what are main clinical signs?
- lambs during first week or two of life
- epiphora, blepharospasm, corneal abrasion/ulcer
rather than surgery, what are other options for repairing entropion?
- place crimps under lid to pull outward
- inject long acting penicillin in conjunctiva
What is the typical causative agent for pink eye leading to corneal ulcers in goats?
how does otitis media result in corneal ulcer?
facial nerve damage from the otitis media --> damages innervation to lacrimal gland
What is infectious bovine keratoconjunctivitis and what is typically the causative agent?
- pinkeye (conjunctivitis that can progress to corneal ulcer)
- Moraxella bovis which is spread by flies (use fly control!) and fomites like you!
Concurrent infections with what virus leave cows more prone to pink eye? why are pink eye vaccines not highly efficatious?
- concurrent IBR or recent vaccination with MLV IBR
- M.bovis attach with pili that are constantly changing so vx must match
At what age are bovines most often affected by IBK? How does pink eye progress to corneal ulcer?
- 4-6month old calves mostly
- M.bovis secretes proteases that cause ulceration
what is the significance of neovascularization with IBK?
new vessels form at the limbus at day 4-7; once they reach the lesion, healing accelerates
What is appropriate treatment for mild case of IBK?
- *subconjunctival* antibiotic like Procain Penicillin G, Ceftiofur Na (Naxcel) or ampicillin
- (NO topical oxytet; lipophilic = irritates tissues!)
- *parenteral* Abs like oxytet, tilmicosin, florfenicol (these are lipid soluble so can penetrate to affect corneal tissue)
What can be done in addition to antibiotics in more severe cases of IBK?
- eye patches
- 3rd eyelid surgery flap
what is common causative agent of pink eye in sheep? what perpetuates the disease in this species?
- Chlamydophila pecorum
- (can affect even young lambs so rule out entropion!)
Pink eye may occur alone in sheep or be found in conjunction with what other disease process?
polyarthritis (stiff lamb disease)
what is appropriate treatment for pink eye in sheep? is there a vaccine?
- parenteral oxytet, NSAIDs (relapses common)
- chlortetracycline can be given in feed to limit outbreaks
- vx for Chlamydophila abortus = Enzootic Abortion of Ewes
What is causative agent of pink eye in goats? what is often seen concurrently in this species?
- Mycoplasma spp.
- polyarthritis, septicemia, mastitis, abortions
- (same tx as sheep = parenteral oxytet, NSAIDs)
what is most common neoplasia of large animals and is also responsible for 1/8 of all bovine carcass condemnations?
- ocular squamous cell carcinoma (cancer eye)
- think Hereford!
Describe rate of invasion and likelihood of metastasis for SCC.
- slow invasion but eventually causes tissue/bony orbit destruction
- slow to met but eventually goes to regional lymph nodes
What is appropriate treatment for localized SCC with distinct borders and no other damage to the eye/orbit?
- topical analgesia/sedation and debulk w/15 blade + cryotherapy followed by Abs/NSAIDs
- (looks worse before better)
What do you do if SCC is localized to 3rd eyelid? what if its localized to conjunctiva?
- remove entire 3rd eyelid
- conjunctiva: debulk and cryotherapy then recheck
if SCC is localized to the eyelid but surgical removal would result in inadequate coverage of the cornea, what should you do?
check the other eye first to make sure it's healthy then enucleate/exenterate the cancer eye (awake with retrobulbar block)
what is recurrence rate following treatment for SCC? Recurrence with exenteration?
- 30-40% recur after tx
- 10-20% recur after extirpate
What happens if farmer opts to just send his cancer eyed cow to slaughter?
- if localized to globe with no other parts involved = condemn head, pass carcass
- condemn entire carcass if bony involvement, necrotic tissue involved, enlarged lymph nodes/mets, cachexia
If cow presents with exophthalomos due to bovine leukemia virus, what should you do Doc?
there is no treatment, removing eye can prolong life but lymphoma may be widespread in the animal
which species has issues with blocked nasolacrimal ducts? treatment?
- find nasolacrimal opening and flush under sedation
If the farmer calls and says the new calf looks like it has a hairball attached to the eye, what is it?
dermoid (sx remove)