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What is the most common neoplasm in cattle?
ocular SCC
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Ocular SCC is associated with... (3)
lack of pigmentation around eye, exposure to intense UV, increasing age
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What are the stages of ocular SCC?
hyperplastic plaques--> regression OR papillomas--> non-invasive or invasive carcinoma
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What are the predilection sites for ocular SCC? (3)
medial canthus/ 3rd eyelid, lateral limbus (border of sclera), lower lid
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It's important to remember that ocular SCC is...
locally invasive but rarely metastatic
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What are the treatment options for ocular SCC? (6)
enucleation/ exenteration, surgical excision, radiowave diathermy, beta radiation, immunotherapy, salvage
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What are anesthesia requirements for eye surgery? (3)
peri-orbital anesthesia to globe an adnexa: motor to upper eyelid, local infiltration around bony orbit (sensory), and peterson block or retrobulbar block (motor)
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What is cause for condemnation with ocular SCC?
extension to a peripheral lymph node, parotid ln.
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Where is lidocaine deposited for blockage of motor innervation to the upper lid?
along the zygomatic arch
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What is the purpose of the peterson nerve block?
desensitizes the muscles of the eye and globe
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What is the purpose of the retrobulbar block?
should cause proptosis of the eye
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When is exteneration of the eye performed?
removal of contents of the bony orbit (globe, muscles, connective tissue), usually due to SCC that extends deep into the orbit
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Why is it important to work quickly when performing exteneration of the eye?
lots of bleeding! minimize blood loss
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When is high-frequency radiowave diathermy performed?
small tumors (ocular SCC) [if you want to use it on a larger mass, debulk first]
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What is a surgical technique commonly used when there is SCC involvement of the lower eyelid?
sliding H-plasty (kinda create a new eyelid of sorts)
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When a cow comes in with a proptosed eye, what are important differentials? (2)
ocular SCC, retrobulbar lymphosarcoma (BLV)
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What is the etiology of infectious keratoconjunctivitis? What is transmission usually associated with?
Moroxella bovis; face flies, dust, sunlight
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Moroxella bovis exists in two forms, which are __(2)__, but the _______ form causes ________.
piliated and non-piliated; piliated; corneal ulcers
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Clinical signs of pinkeye. (7)
blepharospasm, photophobia, lacrimation, ulceration, corneal edema, resolution or perforation may result
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What is treatment for pinkeye? (5)
- systemic oxytet and tulithromycin
- subconjunctival injection +/- steroid
- temporary third eyelid flap
- vaccination
- fly control
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