Equine Adnexa and Nasolacrimal System Disorders Flashcards
Describe the innervation of the eyelid
Sensory: branches of Trigeminal (V) nerve
Motor: facial (VII) nerve with some input from oculomotor (III) nerve
Describe the Nictitating membrane (Third eyelid)
T-shaped cartilage ventromedially on the eye with a gland of the third eyelid. The movement of the third eyelid is passive (it moves up when the globe is retracted or pushed back)
Briefly describe the conjunctiva
Its one continuous structure that has a palpebral portion (lining the eyelids), a bulbar (covering the globe), a fornix (a blind sac or where bulbar and palpebral conjunctiva join) and nicitans/third eyelid conjunctiva
Briefly describe entropion and the treatment options for it
Entropion is the inversion of the eyelid margin that is the most common neonatal ocular abnormality in foals. It can be treated with temporary tacking sutures, addressing underlying disease (dehyrdation) or in rare cases you can perform a Hotz-Celsus procedure
A horse comes into your clinic after lacerating its eye on an old fence, how should you treat it?
You want to deal with it promptly under standing or general anesthesia accompanied by an auriculopalpebral nerve block with local infiltration of lidocaine. The wound should be cleaned with saline or dilute betadine and then freshen/scrape with the blade but presernve the eyelid margin. Then do a 2 layer closure of the tarsoconjucntival and musculocutaneous layers. Afterwards, give them a protective mask, triple antibiotic ointment, systemic NSAIDS, +/- systemic antibiotics.
how should you close an eyelid laceration?
do a two layer closure of the tarsoconjunctival and musculocutaneous layers by using a figure 8 or horizontal mattress suture . Make sure you appose the margins without a know contacting the cornea .
T/F: when repairing an eyelid laceration you want the sutures to penetrate through the palpebral conjunctival surface
F! it will scape the surface of the cornea
How does Facial Paresis and Paralysis effects the eyes?
The horse can’t blink which causes the formation of spontaneous ulcers that can’t heal well
how should you treat eyes effected by facial paresis? whats the prognosis?
- topical lubrication 4-6 times a day
- management of ulcers if present
- partial temporary tarsorrhaphy
- manage underlying conditions
most traumatic cases resolve within 3-4 weeks and prognosis declines significantly after this you could consider permanently closing the eyelid after this
Describe the conjunctivitis
Inflammation of the palpebral and/or bulbar conjunctiva including clinical signs of hyperemia, chemosis, and ocular discharge. This is usually a secondary issue (corneal disease, uveitis) that can be diagnosed by cytology or culture and treatment depends on the underlying cause.
what is the most common neoplasm of horses?
sarcoids
Describe sarcoids and their treatment
typically these appear in young horses and while mets are rare recurrence is very common. Surgical excision has better success with adjunctive cryotherapy, hyperemia, radiation, etc. Chemotherapy and Immunotherapy may also be beneficial.
whats the most common neoplasm of the equine eye and ocular adnexa?
SCC and its the second most common tumor overall
SCC is __ invasive and __ to metastasize. It typically effects __ horses and those exposed to __ alot. Treatment is often surgical excision with a __ recurrence reate that can be lowered with __ treatments such as cryosurgery, radiation,etc.
SCC is locally and slow to metastasize. It typically effects light horses and those exposed to sunlight alot. Treatment is often surgical excision with a 50-60% recurrence reate that can be lowered with adjunctive treatments such as cryosurgery, radiation,etc.
Equine Adnexal SCC prognosis
poorer varies with the following from best to worst
corneoconjunctival> third eyelid> eyelid (worse)
explain the anatomy of the nasolacrimal system
The upper and lower puncta drain tears away from your eyes and then enter the canaliculi which lead to the lacrimal sac (within the lacrimal bone) and then travel down the nasolacrimal duct transversing the maxillary sinus and then drains out of the nasal puncta
what is Imperforate nasal punctum and nasolacrimal duct atresia?
This is the most common congenital nasolacrimal abnormality in foals and results in severe epiphora that may become purulent if theres a secondary bacterial overgrowth.
how do you diagnose and treat imperforate nasal punctum and nasolacrimal duct atresia?
Its diagnosed when the nasal punctum isn’t visible, theres an inability to flush NL duct, contrast radiology and/or by culture/susceptibility. The treatment is to create nasal punctum by passing catheter and cutting conjunctia to create nasal ostium. In order to prevent re obstruction suture the catheter in place within NL system and leave it in for 4-6 weeks. Make sure you also treat any secondary infections
Aquired nasolacrimal obstruction and Dacryocystitis
This is pretty uncommon but will also have epiphora and mucopurulent discharge. It’s diagnosed by a Jones test, NL duct flush or culture. The treatment is to flush it out and apply topical antibiotics (solution)
