Page 471 - Cote clinical veterinary advisor dogs and cats 4th

210 Corneal Ulceration

• ± Corneal vascularization (slow to vascularize) • Corneal culture and sensitivity: ideally, • ± Systemic nonsteroidal antiinflammatory
drug (NSAID)
• Not infected sample obtained before Schirmer tear test Complex corneal ulcer: any or all of the above
VetBooks.ir Etiology and Pathophysiology • STT: normal > 15 mm/min in dogs, variable and one or more of the following (treatment
(STT) and topical anesthesia
frequency decreases as improvement is seen):
in cats
• Trauma
• Ocular foreign body
• Tear film abnormalities • Fluorescein dye application: stains exposed • Anticollagenase therapy is indicated if
stroma to confirm and demarcate ulcer
keratomalacia/melting/stromal loss detected
○ Keratoconjunctivitis sicca • Corneal cytologic evaluation: assess for ○ Autogenous serum q 1-4h (prepared by
○ Mucin and/or lipid deficiency (i.e., qualita- evidence of infection, such as neutrophils, obtaining a sample of a healthy dog’s
tive tear film deficiency) bacteria (gram-positive cocci, gram-negative blood, coagulating and centrifuging and
• Eyelid conformational abnormalities rods), and/or fungal hyphae. Identification using the supernatant [serum] topically for
○ Entropion/ectropion of microorganisms can direct initial choice its antiprotease, anticollagenase properties)
○ Distichiasis/ectopic cilia/trichiasis of therapy. and/or
○ Lagophthalmos (incomplete closure of the • Intraocular pressure to rule out glaucoma ○ Oxytetracycline/polymyxin B (Terramy-
eyelids, usually in brachycephalics) (recommended for any form of red eye) cin) ointment topically q 4-6h or oral
• Neurologic disorders (e.g., facial nerve doxycycline 10 mg/kg q 12-24h
paralysis [cranial nerve VII lesion]; corneal Advanced or Confirmatory Testing • Topical fluoroquinolone antibiotic (e.g.,
denervation [cranial nerve V lesion]) • Keratectomy sample for corneal histopatho- ciprofloxacin, ofloxacin, or levofloxacin q
• FHV-1 infection logic evaluation 4-6h) for improved corneal penetration and
• Corneal sequestration: cats (p. 208) • Corneal swab and/or keratectomy sample spectrum of activity. Use at increased fre-
• Simple corneal ulcers may progress to for polymerase chain reaction (PCR) assay quency (q 2h for 12-24h) for keratomalacia/
complex or ruptured corneal ulcers secondary (FHV-1, bacterial, fungal) melting/stromal ulcer. Alternatively, cefazolin
to bacterial infection or sterile inflammation. 33 mg/mL in artificial tears and ophthalmic
• Indolent ulcers result from a primary TREATMENT tobramycin can be used for broad-spectrum
defect of corneal epithelial adhesion to the activity at same frequency as above.
underlying corneal basement membrane and Treatment Overview • ± Topical antifungal agent q 4-6h (e.g.,
stroma. Goals of treatment: natamycin, voriconazole, miconazole) if
• Treat any underlying cause fungal keratitis is implicated by corneal
DIAGNOSIS • Prevent progressive loss of corneal stroma cytologic evaluation and/or culture (fungal
and corneal rupture. keratitis is rare in cats and dogs)
Diagnostic Overview • Eliminate ocular pain. • Hospitalization of animals with deep or
• Corneal ulceration is suspected based on • Prevent or eliminate corneal infection. rapidly progressive ulcers for frequent medical
history, and the cornerstone of diagnosis is • Promote corneal epithelialization. treatments and monitoring
a complete ophthalmic examination, includ- • Minimize corneal scarring. • ± Structural surgical repair (i.e., keratectomy
ing tear testing and fluorescein staining and to remove the diseased cornea with placement
assessment of the cornea for edema, vessels, Acute General Treatment of a graft: conjunctival, corneal); referral
pigment, cellular infiltrate, fibrosis, and Simple corneal ulcer: procedure is advisable if
epithelial and stromal defects. • Broad-spectrum topical antibiotic solu- ○ Stromal loss continues despite aggressive
• Goals of the ophthalmic exam are to 1) tion or ointment (e.g., triple antibiotic or appropriate medical management
confirm that an ulcer is present (versus oxytetracycline/Polymyxin B) q 6h ○ Ulcer exceeds 50% stromal depth or is
healed defects), 2) determine if there is an ○ Gentamicin is a poor first choice because ruptured
underlying cause, 3) determine whether the of its narrow spectrum for primarily gram- Indolent/refractory ulcer:
ulcer is acute or chronic (consider history negative bacteria (ocular flora is primarily • Application of topical ophthalmic anesthetic
and presence/length of corneal vessels), 4) gram-positive bacteria). (e.g., proparacaine 0.5% solution) with
determine the depth of the ulcer (and risk • Topical atropine 1% ophthalmic solution or without sedation or general anesthesia
of perforation), and 5) determine whether or ointment q 12-48h (depending on the temperament of the dog)
the ulcer may be infected (presence of
cellular infiltrate, marked pain, uveitis,
stromal loss).
• When infection is suspected, corneal culture
and susceptibility and cytologic examination
are indicated for appropriate antimicrobial
therapy.
Differential Diagnosis
• Corneal facet (re-epithelialized stromal ulcer)
• Corneal dystrophy, degeneration or scarring
• Proliferative/eosinophilic keratoconjunctivitis
(cats)
• Anterior uveitis
• Horner’s syndrome
Initial Database
Neurologic (p. 1136) and ophthalmic (p. 1137)
examinations:
• Cranial nerve examination: menace response,
pupillary light reflexes, palpebral and corneal CORNEAL ULCERATION Debridement of an indolent corneal ulcer of the right eye in a dog. Note the lip
reflexes of nonadherent corneal epithelium (arrows) attached to the sterile cotton-tipped applicator (asterisk).

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