L25: Ruminant Ophthalmology (Plummer) Flashcards
Causes of ORBITAL inflammation and CS/Tx
- trauma
- FB
- panophthalmitis
- neoplasia (ie. Lymphoma)
CS: pain, anorexia, exophthalmos, pyrexia, leukocytosis
Tx: address 1ary cause, hot-packing, drainage, abx, enuc?
Causes of CORNEAL inflammation and CS/Tx
- trauma, neoplasia
- Infectious Bovine keratitis (pinkeye) by far most common**
CS: blepharospasm, epiphora, opacity, vascularization, uveitis
Tx: address 1ary cause, abx, enuc?
Infectious Bovine keratitis aka
Pinkeye
Contagious ophthalmia
New Forest Dz
Etiology of IBK***
- worldwide distr.
- higher incidence in spring/summer
- 2nd most common problem in calves
Other agents that presumably cause IBK
Chlamydophila spp. Mycoplasma IBR virus Branhamella spp. Listeria monocytogenes Thelazia spp.
IBK predisposing factors
- breed (Bos taurus)
- age (young)
- flies
- mechanical/env. Irritants
- UV radiation
- concurrent infections
CS of IBK
- keratitis/central ulceration
- conjunctivitis
- uveitis
- blepharitis/photophobia
- serous lacrimation
“24-48 hours after infection, they will become uncomfortable with blepharospasm and epiphora. Superficial corneal ulcer then develops due to cytololytic effects of bacteria. Days after, host response results in formation of abscess. Then, they will either heal or continue to decline and ulcer worsens”
Transmission of IBK
- insects
- mech. Vectors
- direct contact
- nasal aerosols
- fomites
- cow’s repro tract to calf’s eye
Outcomes of IBK
1) resolution w/ corneal scar, keratoconus
2) progression to descemetocele/corneal rupture/synechia/cataract/blindness
(Synechia = iris adheres to cornea or lens)
Properties of Moraxella bovis
- GN, nonmotile diplobacillus
- hemolytic and nonhemolytic forms
- UV can convert nonhemolytic, non-piliated form to piliated pathogenic hemolytic form
Abx for Tx of IBK
- Oxytetracycline and Telathromycin only approved tx
- penicillin
- florfenicol
- ceftiofur
- tilmicosin
- clindamycin
- ampicillin
- gentamycin
- sulfa
- atropine, NSAIDs
- can still be carriers even after abx given
- oxytet has faster time to resolution of CS but has longer withdrawal time
Tx of IBK
- abx
- prevention!!
- husbandry (nutrition, fly control, reduce weeds/dust)
- vaccinate susceptible animals/farms before fly/IBK season
2nd most common category of dz in bovids
Neoplasia
-lymphoma and SCC most commonly affect the eye
Lymphoma affects what structures of the eye
Orbit
Uvea
Conjunctiva
(Systemic dz)
SCC affects what structures of the eye
Cornea Conjunctiva TE Eyelid Orbit
CS of lymphoma of the eye
- exophthalmic
- thickened conjunctiva
- edema in eye (if advanced)
Lymphoma thought to be secondary to:
Infection with bovine leukemia virus
Bos taurus breeds more commonly affected
Prognosis/tx of orbital lymphoma
- poor prognosis
- tx: mainly paliative (can remove eye and orbital tissues to get cow to calving)
Increased incidence of OSCC in what groups?
- older
- UV exposure
- decreased periocular pigmentation
- nutrition
- irritation (chronic inflammation)
- Bovine papillomavirus MAY be implicated
- females? (Males don’t make it to age)
70% of OSCC are located where on the eye
Globe
- can invade the orbital bone, maxilla, frontal bone, anterior chamber
- mets occur more often when SCC is affecting the vascular structures
OSCC is a leading cause of carcass condemnation
:)
Tx of OSCC
- cryotherapy
- enucleation/exenteration
Rarely used:
- radiation therapy
- hyperthermia
- sx resection
- immunotherapy
- chemotherapy
- prevention
- early intervention
Management protocol for OSCC
- eval eyes of each animal over 2 yrs 2-3x/yr
- treat all small SCC with cryo or hyperthermia
- orbital exenteration for large lesions
- invasive and/or metastatic SCC causes condemnation
Common areas of concern for SR eyes
- eyelids
- cornea
- systemic dz
Toxins/teratogens resulting in ocular problems in SR ewe or young
1) veratrum californicum at day 14 gestation –> cyclopia, synophthalmia
2) Photosensitizing agents –> blepharitis
3) selenium –> microphalmia, cystic anomalies
Entropion in SR
- inherited in sheep
- leads to 2ary keratitis
- tx: temporary tacking, surgical correction
- presents very young, usually in lower lid
- should cull from breeding pop.
Infectious keratoconjunctivitis
- multifactorial dz with varied agents
- due to poor husbandry, carriers
- Causative agents: Chlamydia, Mycoplasma, Branhamella
CS of Infectious KCS from CHLAMYDIA:**
Serous discharge initially, then becomes mucopurulent ~11 days post-infection. Then will either clear or get worse with corneal infiltrates
- Only 10% of individuals will get keratitis
- Worse in stressful times of year (lambing/kidding season)
CS of Infectious KCS from MYCOPLASMA:**
-MAJORITY develop keratitis***
Sheep usually get worse CS than goats**:
-sheep get conjunctivitis which can turn into keratitis + uveitis, ulceration, whereas goats don’t usually get uveitis or ulceration
Dx of infectious KCS
- CS
- Cytology: see intra-cytoplasmic “speckles” if have Branhamella, and phagocytized neuts with Mycoplasma**
- Culture
- IFA
- PCR
Tx of Infectious KCS
- oxytetracycline (most commonly used)
- tetracycline
- tx secondary uveitis with atropine, NSAIDs
- better husbandry and eliminate carriers
Common areas of concern in camelid eyes
- cornea
- nasolacrimal system (more commonly have incomplete system)
- uvea
- lens
- very similar to HORSE in tx protocols!
- more susceptible to systemic dzs that more commonly result in uveitis than in other species
Camelid cornea predisposed to:
- ulcerative keratitis
- endothelial degeneration
- tx same as in horse!
- culture, cytology, put SPL in, treat topically
- susceptible to same types of surface infections
- endothelium sensitive and can develop permanent corneal edema
- can do sx therapy and apply conj flaps
Common areas of concern
- orbit
- cornea
- adnexa
