Page 948 - Cote clinical veterinary advisor dogs and cats 4th

Herpesviral Keratitis, Cats 465

• Individual variation in susceptibility to recru- plaques extending from the limbus often TREATMENT
descent herpetic keratitis suggests immunologic with a leading zone of ulceration. Although Treatment Overview
VetBooks.ir RISK FACTORS chain reaction (PCR) FHV-1–positive cats, • Cats with primary and mild recrudescent Diseases and Disorders
predisposition.
this condition is seen in many polymerase
herpetic keratitis may improve with support-
proof of a causal relationship has not been
Stresses such as rehousing, concurrent disease, or
found.
pregnancy/parturition/lactation; glucocorticoid • Corneal sequestration appears as a flat or ive care only. Cats with severe or frequently
recurrent keratitis require specific antiviral
administration; multi-cat households or shelters; raised, amber to black lesion on the axial to therapy.
inadequate vaccination paraxial cornea, often surrounded by corneal • Many topical or systemic antiviral agents are
vascularization and sometimes stromal limited by their toxicity and efficacy profiles.
CONTAGION AND ZOONOSIS inflammatory cell infiltration (p. 208). • No antiviral drug has been developed to date
• Highly contagious to naive cats; carrier cats Sequestra most likely develop secondary to for cats infected with FHV-1. Antiviral drugs
do not become reinfected (but virus may chronic corneal ulceration. developed for human herpesvirus infections
reactivate) • Symblepharon (scarred fusion of conjunctival are used. None has readily predictable safety
• Not zoonotic surfaces to each other or to the cornea) in cats or efficacy against FHV-1.
GEOGRAPHY AND SEASONALITY Etiology and Pathophysiology Acute General Treatment
• Worldwide viral distribution without • FHV-1 is ubiquitous; the virus replicates • Cats with concurrent respiratory signs may
seasonality in epithelial cells, especially those of the need supportive care (consider systemic
• Because of higher susceptibility of kittens, conjunctiva, and then ascends by axons antibiotics, fluid, and nutritional support).
trends in disease prevalence may be noted to establish latency in the trigeminal • Cats with ulcerative keratitis require a topical
in association with feline breeding seasons. ganglia. broad-spectrum antibiotic because antiviral
• Primary disease is common and usually drugs are not antibacterial. Ophthalmic
ASSOCIATED DISORDERS self-limited. oxytetracycline (Terramycin) is a good choice
• FHV-1 also causes rhinitis, conjunctivitis, • At least 80% of affected cats become latently because it is effective against C. felis, which
and dermatitis and may cause anterior uveitis infected for life; periodic viral reactivation is a common cause of conjunctivitis.
secondary to corneal ulceration. occurs in at least one-half of those latently • Consider antiviral treatment for chronic, recur-
• FHV-1 is associated with corneal sequestra, infected. rent, or severe signs. Topical antiviral agents
symblepharon, and proliferative (eosino- • Periodic recrudescent disease occurs in a (e.g., idoxuridine, trifluridine, vidarabine) are
philic) keratoconjunctivitis. minority of cats undergoing viral reactivation. virostatic and must be administered at least q
4h. The exception is cidofovir, which because
Clinical Presentation of tissue accumulation may be administered
DISEASE FORMS/SUBTYPES DIAGNOSIS q 12h. These medications should be adminis-
• Ulcerative keratitis (seen most often on initial Diagnostic Overview tered for at least 1 week after ulcer resolution.
exposure but also in recurrent forms) The frequency with which cats are vaccinated • Systemic acyclovir is not recommended
• Nonulcerative keratitis (seen most often in and the number of normal cats that shed virus due to toxicity. Valacyclovir is an acyclovir
recurrent or chronic primary forms) at ocular sites make serologic testing (97% prodrug with fatal toxicity.
seroprevalence) and methods of viral detection • Systemic famciclovir 90 mg/kg PO q 12h
HISTORY, CHIEF COMPLAINT (e.g., PCR) unhelpful. Inclusion bodies are reduces clinical disease and viral shedding,
• Ocular discharge (serous to mucopurulent) rarely seen on cytologic specimens. Diagnosis produces effective plasma and tear drug con-
• Blepharospasm is made based on visualization of dendritic centrations, and appears to be well tolerated.
• Corneal opacification ulcers or geographic ulcers, supportive signs, Like other antimicrobials, it should be given
• Upper respiratory signs may be seen, includ- and/or response to therapy. beyond resolution of clinical signs and not
ing nasal congestion, sneezing, and serous tapered.
or mucopurulent nasal discharge. Differential Diagnosis • Many cats benefit from mucinomimetic
• Ocular signs are typically bilateral in • There are no other recognized primary feline tear-replacement products, especially those
primary disease but often unilateral during corneal pathogens. containing hyaluronate.
recrudescence. • Chlamydia felis (formerly Chlamydophila felis • Avoid topical or systemic administration of
or Chlamydia psittaci) causes conjunctivitis corticosteroids, nonsteroidal antiinflamma-
PHYSICAL EXAM FINDINGS but is not known to cause keratitis. tory agents, cyclosporine, or tacrolimus.
• Ocular discharge: epiphora, mucoid, • Feline calicivirus is not a primary corneo-
purulent, sanguineous, or dry and crusty; conjunctival pathogen but causes lesions of Chronic Treatment
sometimes dark red or black oral/pharyngeal mucosa. • Lysine 500 mg/CAT PO q 12h: lifelong
• Blepharospasm • Noninfectious corneal disease (immune treatment; may reduce viral replication in
• Corneal ulceration: dendritic early; may mediated, neoplastic, keratoconjunctivitis some cats with frequent recurrences. Give
become geographic; often chronic, non- sicca, foreign body, traumatic) is uncommon as q 12h bolus; do not add to food. Do not
healing and sometimes with a lip of loose in cats compared with dogs but should be continue lifelong if a positive effect is not
epithelium considered. seen after a reasonable amount of time.
• Deep or superficial corneal vascularization • Avoid prolonged topical antiviral administra-
• Corneal opacification due to white blood cell Initial Database tion due to corneal toxicity.
infiltration and/or edema and/or scarring • Thorough ophthalmic exam (p. 1137), • Avoid topical or systemic administration
• Conjunctival or episcleral hyperemia including Schirmer tear testing, tonometry, of corticosteroids, nonsteroidal antiinflam-
• Chemosis (conjunctival edema), blepharedema and application of fluorescein and sometimes matory agents, cyclosporine, or tacrolimus
• Reflex uveitis: miotic pupil; aqueous flare rose bengal or lissamine green stains because they may lead to recrudescence.
and/or inflammatory cells in the anterior • Corneal or conjunctival cytologic evaluation
chamber, low intraocular pressure (p. 1023) important for diagnosing eosinophilic/ Nutrition/Diet
• Proliferative (eosinophilic) keratoconjunctivi- proliferative keratoconjunctivitis; however, High-lysine (≈5%) diets have proven
tis: appears as raised, pink, sometimes chalky herpesviral inclusions are rarely seen. counterproductive.

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