Bovine Ophthalmology Flashcards
(45 cards)
1
Q
OCULAR ANATOMY
A
2
Q
NORMAL RUMINANT ANATOMY
A
• Complete bony orbit
• Upper & lower lacrimal puncta
• Horizontal pupil
• Corpora nigra
• Tapetum lucidum with “stars of Winslow”
• Holangiotic fundus
3
Q
CONGENITAL ABNORMALITIES
A
- Bovine viral diarrhea virus (BVDV)
- Bluetongue virus
- Dermoid
4
Q
BOVINE VIRAL DIARRHEA VIRUS
A
- Pestivirus
-
Most common maternal infection causing multiple ophthalmic defects
- Usually between 76 – 150 days of gestation
- Skeletal and CNS abnormalities
- Range of ocular defects in calves
- Cataracts, microphthalmia, PPMs
- Retinal dysplasia
- Chorioretinitis: retinal degeneration, ONH atrophy, chorioretinal scarring
5
Q
BLUE TONGUE VIRUS
A
6
Q
BLUE TONGUE VIRUS
A
7
Q
BLUE TONGUE VIRUS
A
- Orbivirus
- Culicoides gnat vector
- “Dummy” calves
- Hydrancephaly
-
Blindness with normal PLRs
- Cortical blindness
- Profound corneal edema
8
Q
DERMOID
A
- Plaque of differentiated skin in an abnormal location
- Temporal limbus most common site
- Also third eyelid, medial/lateral canthus, eyelid, conjunctiva
- Inherited in Herefords
- Breeding recommendations
- Treatment
- Small and hairless → benign neglect
- Painful or impairing vision → superficial keratectomy
9
Q
ESOTROPIA
A
- Bilateral Convergent Strabismus and Exophthalmia (BCSE)
- Inherited
- Affects many breeds
- Brown Swiss
- Jersey
- Progressive
- Abducent nerve motor nucleus defect (histopathologic finding)
10
Q
ACQUIRED ABNORMALITIES
A
- Acquired strabismus
- Orbital disease
- Blepharitis
- Keratitis
- Conjunctivitis
- Neoplasia
11
Q
ACQUIRED STRABISMUS
A
12
Q
ORBITAL DISEASE
A
• Space occupying lesions
• Most common clinical sign is exophthalmos
• Prognosis depends on etiology
• Neoplastic
• Inflammatory/infectious
13
Q
ORBITAL NEOPLASIA
- name some
A
• Lymphosarcoma
• Caused by BLV
• Diagnosis via biopsy
• Palliative treatment for orbital lymphosarcoma (<6 months)
• Metastatic SCC
• Metastatic adenocarcinoma
• Meningioma
• Lymphangiosarcoma
14
Q
ORBITAL NEOPLASIA
- clinical signs
A
- Physical exam may reveal systemic abnormalities
- Lymphadenopathy
- Melena
- Cardiac arrhythmia
- Uterine and renal masses
15
Q
ORBITAL INFLAMMATION
A
- Cellulitis/abscess
- Other associated signs of disease
- Causes:
- Trauma to ocular tissues
- Plant foreign material (oral)
- Dehorning
- Actinomyces pyogenes
- Frontal or maxillary sinusitis
- Pasteurella multocida
- Actinomyces pyogenes
- Treatment:
- Address underlying disease
- Systemic antibiotics
- Trephine/drain/lavage
- Enucleation
16
Q
BLEPHARITIS: BACTERIAL
A
- Dermatophilosis
- Dermatophilus congolensis
- Filamentous, gram + aerobe
- Infective motile stage in wet scabs
- Distal extremities, muzzle, & dorsum
- Treatment:
- Dry environment (iodine or chlorhexidine shampoo)
- Penicillin (20,000 IU/kg) +/- streptomycin (10 mg/kg) IM for 3-5 days OR one long-acting oxytetracycline (20 mg/kg) injection
17
Q
BLEPHARITIS: FUNGAL
A
- Dermatophytosis
- Trichophyton spp.
- Usually self-limiting; immune to reinfection
- Goal of treatment = limit spread to unaffected animals and humans
- ZOONOTIC
- Treatment:
- Topical and systemic antifungals, iodine shampoos, dry environment, and good nutrition
- Vaccination available
18
Q
BLEPHARITIS: PARASITIC
A
19
Q
BLEPHARITIS: PHOTOSENSITIVITY
A
- Photodynamic agents → UV sensitivity
- Do not confuse with solar irritation (sunburn)
- Acute periocular changes +/- corneal edema
- Identify underlying cause
- Primary: Ingestion of photodynamic agents
- Secondary: Hepatitis and/or bile duct obstruction leading to phylloerythrin accumulation systemically
- Inherited: Defects in porphyrin metabolism
- Treatment
- removal from sunlight
- prevention of ingestion of toxins +/- laxatives
20
Q
CORNEA & CONJUNCTIVA
A
• Major sites for ophthalmic disease in food animals
• Profound economic impact
21
Q
KERATITIS/CONJUNCTIVITIS
A
- Infectious bovine keratoconjunctivitis (IBK)
- Malignant Catarrhal Fever (MCF)
- IBR
- Listeria
- Thelazia spp.
- Environmental factors (e.g. dust/pollen/fumes)
22
Q
INFECTIOUS BOVINE KERATITIS (IBK)
- agent
- properties
- transmission
A
- “Pink eye”
-
Moraxella bovis
- Other possible agents(?): IBR, M. ovis, M. bovoculi, Mycoplasma spp
- Gram-negative bacillus
- Pathogenic enzymatic properties
- Multiple organism serotypes
- Some nonpathogenic
- Transmission
- New animal, fomites, contact, and handlers
- Vectors: face fly (Musca autumnalis), house fly (Musca domestica), and stable fly (Stomoxys calcitrans)
23
Q
IBK
- environmental factors
- predisposing factors
A
-
Environmental factors
- Sunlight (UV radiation)
- Dry environment (dust, pollens, grasses)
- Shipping stress
- Face flies → number correlates with infection rate!
-
Predisposing factors
- Bos taurus > Bos indicus breeds
- Herefords & Hereford crosses most common
- Increased incidence/severity in young cattle
- < 2 years of age
24
Q
IBK
- pathogenesis
A
- Pathogenic strains are piliated
- Q pili – attachment to corneal epithelium
- I pili – maintenance of infection
- Bacteria release enzymes (β- hemolysin)
- Damage corneal epithelium & allow access to stroma
- Proteases
- Released by neutrophils & corneal cells
- Lead to progression of ulcer
25
IBK
* timing of disease
* source
* prevalence
* Acute disease, spreads rapidly
* Source is new animal or carrier in herd
* **Increased prevalence in summer**
* UV radiation induced damage to corneal epithelium
* UV radiation induces M. bovis to more aggressive form
* Face flies more numerous
26
IBK
* signs
* Unilateral or bilateral
* Photophobia, blepharospasm, epiphora
* Conjunctivitis +/- mucopurulent exudate
* Central corneal lesion (opacity → ulcer)
* Corneal vascularization +/- granulation tissue
* Corneal rupture
* Secondary uveitis +/- glaucoma
* **Anorexia results in ECONOMIC LOSS**
* Painful and potentially blind
* ↓ milk production
* ↓ weight gain
27
IBK
* treatment
28
IBK MEDICAL THERAPY
29
IBK PREVENTION
**• Fly control**
• Dust bags, insecticide tags, or topical drenches
• Temporary isolation of new animals
• Provide shaded areas
• Personnel disinfection
• Vaccination protocol
• M. bovis bacterins
• Efficacy questioned
• Administer BEFORE fly season
30
INFECTIOUS BOVINE RHINOTRACHEITIS (IBR)
• Etiology: bovine herpes virus (BHV-1)
• Ocular signs (+/- respiratory disease)
• **Conjunctivitis**: red/white raised plaques (lymphocytic follicles)
**• NON-ulcerative keratitis**
• Edema and vessels
• Blinding when severe
• Discharge: serous à mucopurulent
• +/- Anterior uveitis
• May be concurrent with IBK
• Disease course 2-4 weeks (vaccines available)
31
MALIGNANT CATARRHAL FEVER (MCF) KERATOCONJUNCTIVITIS
* etiology
* types → signs
* Etiology: herpes virus
* ovine HV-2 or alcelaphine HV-1
* Variations in clinical signs
* “Head-and-eye” is classic manifestation
* Other forms affect skin, mucosal surfaces, gastrointestinal and nervous system
* Pyrexia, profuse nasal/ocular discharge, mucosal erosions, dyspnea, diarrhea, & death
32
MCF
**• Ocular Signs**
* Photophobia
* Excessive lacrimation
* Exophthalmos
* Nystagmus
* Conjunctivitis (severe)
* Keratitis
* **Perilimbal corneal edema** progressing to complete opacification
* Bullous keratopathy and corneal erosions are common
* More severe than IBR
33
MCF
* diagnosis
* prevention
• Diagnosis
• PCR testing available
**• Grave prognosis**
• Prevention
• No vaccine or treatment
• Keep cattle away from sheep in endemic regions
34
BOVINE OCULAR SQUAMOUS CELL CARCINOMA (OSCC)
* who
* why important
• Cattle most affected of production animal species
• BPV may play a role
**• Most economically important neoplasm of large animals**
• Accounts for 9.15% of slaughterhouse condemnations
35
OSCC
* risk factors
**• Periocular depigmentation**
• Hereford, Ayrshires, Simmental
**• UV radiation**
**• Age**
• Older cattle ↑ risk (average age 8.1 yrs)
**• Genetic predilection**
• Bos taurus \> Box indicus
• Herefords overrepresented
36
CLINICAL FINDINGS (OSCC)
* Any ocular or periocular location
* 75%: bulbar conjunctiva and cornea
* 90% on limbus and 10% on cornea
* 25% affect palpebral conjunctiva, nictitating membrane, eyelids
* Multiple or single lesions
* Unilateral or bilateral
37
OSCC PATHOPHYSIOLOGY
* Progressive disease with malignant transformation
* Hyperplastic epithelial plaque (**may regress**) → papilloma (**may regress**) → noninvasive carcinoma (in situ) → invasive carcinoma
* **Local invasion may be aggressive**
* Palpate orbital rim
* Bony involvement had poor prognosis
* **Metastasis is rare and occurs late in disease**
* 5% of animals at slaughter (higher if invasive SCC)
* Systemic metastasis more common with eyelid and nictitating membrane tumors
* Local lymph nodes and lungs
38
OSCC DIAGNOSIS & TREATMENT
* Diagnosis
* Appearance
* Histopathology (biopsy)
* Treatment:
* **\*consider practicality\***
* **Surgical excision** (most common)
* **Cryotherapy/laser therapy** (CO2)
* **Enucleation or exenteration**
* +/- block resection: retropharyngeal ln, mandibular salivary gland, parotid salivary gland and subparotid ln
* **Euthanasia/slaughter**
* Hyperthermia
* Immunotherapy
* Radiation
* Photodynamic therapy
* Recurrence rate 30-40%
39
OSCC PREVENTION
* Selective breeding
* Pigment around the eyes
* Lines without high incidence of disease
* Difficult to manage environmental factors
40
UVEITIS
* Neonatal infections
* Umbilical infection, pneumonia, scours, etc.
* Bacterial septicemia in adults
* Mastitis, metritis, traumatic reticuloperitonitis, MCF, IBK, TEME, listeriosis, tuberculosis, neoplasia, trauma
* Clinical signs
* Pain, photophobia, flare, hypopyon, miosis, swollen iris, peripheral corneal edema and vessels
* Secondary changes: glaucoma, cataract, phthisis bulbi
* Treatment
* Topical steroids, topical atropine, flunixin meglumine
* Address underlying cause if known
41
OCULAR SURGERY
42
NERVE BLOCKS
**• Auriculopalpebral nerve block**
**• For ocular examination or surgery**
**• Causes eyelid akinesia**
• Inject lidocaine SQ where nerve crosses zygomatic arch
• 5-7 cm caudal to supraorbital process
**• Local lidocaine block**
**• For eyelid anesthesia during surgery**
• Inject lidocaine SQ at planned incision site
• “Ring block” for enucleation or exenteration
43
PETERSON NERVE BLOCK
* Retrobulbar block for CATTLE
* Blocks cranial nerves II, III, IV, V (ophthalmic and maxillary branches only), and VI
* Insert 10 cm, 18g needle at caudal angle between supraorbital process and zygomatic arch → direct posterior and walk off coronoid process anteriorly → advance to pterygopalatine fossa → inject 15-20 mL of lidocaine
* **Mydriasis indicates successful block**
* Complications: apnea, death 8-9 minutes later if inject into vessel or nerve sheath
44
FOUR POINT BLOCK
• Retrobulbar nerve block for surgery
• Insert 6 cm needle transconjunctivally adjacent to the globe
• Dorsal, medial, ventral and lateral
• Inject 5-10 mL of lidocaine at each site
**• Mydriasis indicates successful block**
45
“EN BLOC” TRANSPALPEBRAL ENUCLEATION
