Bovine Ophthalmology Flashcards

Question

IBK * timing of disease * source * prevalence

Answer 1

* 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

Answer 2

* 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

Answer 3

**• 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

Answer 4

• 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)

Answer 5

* 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

Answer 6

* 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

Answer 7

• Diagnosis • PCR testing available **• Grave prognosis** • Prevention • No vaccine or treatment • Keep cattle away from sheep in endemic regions

Answer 8

• 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

Answer 9

**• Periocular depigmentation** • Hereford, Ayrshires, Simmental **• UV radiation** **• Age** • Older cattle ↑ risk (average age 8.1 yrs) **• Genetic predilection** • Bos taurus \> Box indicus • Herefords overrepresented

Answer 10

* 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

Answer 11

* 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

Answer 12

* 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%

Answer 13

* Selective breeding * Pigment around the eyes * Lines without high incidence of disease * Difficult to manage environmental factors

Answer 14

* 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

Answer 15

**• 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

Answer 16

* 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

Answer 17

• 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**

Bovine Ophthalmology Flashcards

(45 cards)