14 - food and fiber ophtho Flashcards
The orbit in a ruminant is open or closed?
Closed
THe orbit in the pig is open or closed?
Open
What is the shape of a pig’s pupils?
Round - similar to people
Granula iridica (corpora nigra) is present in what animals?
Ruminants and horses
Which two animals do NOT have a tapetum?
Pigs, camelids
What ruminant has a kidney bean shaped optic disc?
Sheep
T/F: ruminants have a holangiotic fundus.
True
Congenital causes of micropthalmia in ruminants
Teratogenic exposure during development
Viral diseases: blue tongue in small ruminants and BVD in cattle
Cyclopia/Synopthalmos is a congenital disorder that occurs when the fetus is exposed to the plant ______ on day ____ in utero.
veratrum californicum; day 14
Two reasons for exophthalmos in ruminants
Neoplasia and Inflammatory (frontal sinusitis, foreign body migration, actinobacillus spp.)
Lymphosarcoma in the eye is most commonly presented bilaterally or unilaterally?
Bilaterally
Between cattle, sheep, goats and pigs, which species is entropion most common in?
Sheep
Entropion in sheep is an inherited abnormlaity that is usually _____ (bilateral/unilateral), and has an early onset within ___-___ days.
bilateral; 2-3 days
Ideal tx vs economically practical tx for entropion
Surgery is ideal
Scarification is more parctical
Two methods to tx entropion via scarification:
Inject penicillin/tetracycline intot he eyelid - will cause scaring, and rotation of the eyelid outwards.
Or you can insert lidocaine into the lid and crush the tissue with hemostates to cause scaring.
T/F: Eyelid lacerations rarely need to be fixed surgically.
False - ALWAYS need to be repaired
Solar irritation (aka sunburn) to the eyelids is common in color ___ cattle.
Dilute
Photosensitization effects the eyelids in ruminants - it can be primary due to eating _____ and _____, or secondary due to _____ _____.
St. John’s wort and perennial rygrass
secondary to liver disease
Two neoplasias on eyelids in cattle
SCC and papillomas
T/F: Papillomas are self-limiting and often do not need tx.
True
Two pathogens in sheep and goats that are etiologic causes for keratoconjuctivitis
Chlamydia spp.
Mycoplasma spp.
C/S of keratoconjunctivitis in sheep and goats due to:
Chlamydia vs Mycoplasma
Both cause: epiphora/discharge; conjunctivitis/keratitis; polyarthritis; and outbreaks occur during lambing
Mycoplasma also causes mastitis and pleuropneumonia
Is it common to test for causes of keratoconjunctivitis in sheep and goats? What do we do when we suspect it?
Uncommon to test - not economically practical
Instead, we just give them topical and/or systemic oxytetracycline empirically
Infectious bovine rhinotracheitis (IBR) is caused by which virus?
Bovine herpes virus - BHV-1
In addition to respriatory disease and pyrexia, BHV-1 can also cause conjunctivitis in cattle. What are common C/S of conjunctivitis caused by this virus?
Plaques - filled with lymphocytes
Conjunctival ulcers
Diphtheritic membrane
Malignant catarrhal fever (MCF) causes _____ vasculitis in cattle.
lymphocytic vasculitis
MCF causes uveitis in cattle, why does uveitis from from MCF?
B/c MCF causes a lymphocytic vasculitis - leading uveitis and corneal edema as a result of uveitis
C/S of MCF
Systemic illness and diffuse, corneal edema with uveitis
Why does Infectious bovine keratoconjunctivitis (pink eye) cause a large economic impact in cattle?
Decreased weight gain
Reduced milk production
Costs of tx
Ocular disfigurement - can lead to blindness, and can lead to head being condemned in slaughter
What contributing pathogens predipose to infectious bovine keratoconjunctivitis (IBK)?
Infectious bovine rhinotracheitis (IBR)
Mycoplasma
Branhamella
Listeria
what is the #1 suspect of IBK? What are two other suspects?
1 = Moraxella bovis
Others: Moraxella ovis and Moraxella bovoculi
Moraxella bovis is a _____ (shape), gram ____ baceteria. Over ___ serogroups have ____ that assist with attachment to epithelium, causing those to pathogenic. Some even contain _____ enzyme that assists in the penetration through the epithelium.
coccobacillus
negative
7
pili
beta-hemolysin
Moraxella ovis and Moraxella bovoculi are also thought to be associated with IBK, but they are also part of the normal _____ of the eye.
flora
IBK is most common in what season?
Summer
How is IBK transmitted?
Nasal and ocular discharge - direct contact
Fly vectors
Fomites
Breed and other susceptibilties to IBK?
Bos taurus >> bos indicus
Herefords
Young animals >> older animals
UV light exposre
Tx of IBK
Use labeled antimicrobials:
topicals include oxytetracycline and vetericyn
Sysetmics include oxytetracycline and tulathromycin
Systemics are more practical than topicals.
You can also use corticosteroids, and ancillary therapy like eyepatch.
Vaccine to prevent IBK includes which two Moraxella pathogens?
M. bovis and M. bovoculi, but NOT M. ovis.
Why do vaccines against IBK prevnetion have limited efficacy?
Due to strain variability
How else can you prevent IBK besides vaccines?
Mow pastures - minimzie dust/pollen and reudce occular trauma from long grasses
Control vectors (flys)
Separate infected and susceptible animals
Provide shade and ample space.
Out of cattle, sheep, goats and pigs, neoplasia affects which species MC?
Cattle
C/S of squamous cell carcinoma
Often starts as a small plaque on the bulbar conjunctiva/cornea at limbus
Turns into papilloma –> carcinoma producing neoplasti cells –> invades basement membrane and becomes an invasive carcinoma
Diagnosis of SCC
Biopsy as definitive dx
Often clinical appearance is enough to know it is a SCC before biopsy
Tx of SCC
Sx + other modality
Exenteration = removal of the globe and orbital contents (= extirpate in food animal world)
Two types of regional anesthesia done, which one is more common?
Peterson block - inject one large dose of lidocaine - can cause death if you inject direclty into optic nerve, not done often anymore.
Four point block - more common, smaller volumes of lidocaine given at four different points
Two congenital reasons for cataracts in ruminants
Autosomal recessive in jersey, hereford, and holstein breeds.
In utero exposure to BVD
Acquired reasons for cataracts in cattle/ruminants
Trauma, uveitis, systemic disease
Acquired reasons for cataracts in swine
Hygromycin B
Differential list for cortical blindness
- Polioencephalomalacia
- Lead poisoning
- Ketosis - small ruminants
- Locoweed
- Lightning strikes
- Infecitous diseases (scrapie, listeria, rabies)
Camelids have an open or closed orbit?
Closed
Camelid orbits open into the ___ cavity rostral to the orbit.
nasal
Camelids have an ____ pupil.
Oval
Camelids have ribbon-like _____ ____, aka _____.
Granula iridica (corpora nigra)
T/F: Camelids have meibomian glands on their eyelids.
False - NO meibomian glands present
T/F: Camelids have sebaceous glands on the lacrimal caruncle.
True.
T/F: Camelids have a holangiatic fundus with no tapetum.
True
The normal nasolacrimal system in camelids has three puncta - where are there locations:
2 in lacrimal - upper and lower
one in nasal - just proximal to vestibule
What is dacryocystitis?
Inflammation of the lacrimal gland, secondary to obstruction of the nasolacrimal duct at the level of the lacrimal sac
Congenital malformations of the nasolacrmial system are common in camelids - which may include punctal or nasolacrimal duct atresia. How do we confirm and tx?
Confirm with dacryocystorhinogrpahy - contrast study to tell us where occlusion is
Tx - surigcal if easy to reach - to create puncta, if not easy to reach - not economically worth while to tx surgically
T/F: Neoplasias of the eye are very common in camelids.
False - rare
T/F: Cataracts are very common in camelids.
True
We think cataracts in camelids are inherited as an autosomal recessive trait in _____ (europe)
Vicunas
Cataracts can also be secondary to ____ or potentially associated with _____ virus.
uveitis; BVD virus
Cataract surgery in camelids include:
Phacoemulsification
Irrigating solutions fortified with glutathione
Medial corneal incision placement
Do camelids have a tapetum?
No
What agents can cuase posterior uveitis in camelids?
EHV-1 (contact with equine)
Aspergillosis
Toxoplasmosis
Ontop of causing posterior uveitis, EHV-1 and asperigillosis also have ____ signs associated with disease.
neurologic
EHV-1 in camelids will cause posterior uvetiis, with neurologic signs, but also ___ neuritis.
optic
