Lecture 22 4/29/25

Question 1

What are the differentials for conjunctival dz in cats, from most to least common?

Answer 1

-herpes
-chlamydia
-mycoplasma
-calicivirus
-bordetella

Question 2

At what age do cats often get infected with a pathogen that causes conjunctivitis?

Answer 2

neonate or juvenile

Question 3

What are the characteristics of herpes virus?

Answer 3

-often accompanied by URI
-only cause of conjunctivitis that also causes keratitis and dendritic ulcers

Question 4

What are the characteristics of chlamydia?

Answer 4

more likely to cause severe chemosis than other causes of conjunctivitis

Question 5

What are the characteristics of calicivirus?

Answer 5

-causes lots of discharge
-more resp. signs than ocular signs
-cats may have oral ulcers

Question 6

What are the characteristics of bordetella?

Answer 6

-causes resp. signs
-usually mild dz
-can spread from dog to cat

Question 7

What is a symblepharon?

Answer 7

-sequela of herpes
-conjunctiva adheres to any surface in the eye

Question 8

What are the characteristics of latency and recrudescence in feline conjunctivitis?

Answer 8

-herpes virus lives in the trigeminal nerve and possibly in the trigeminal branches in the cornea
-herpes recrudesces during times of stress and can manifest as keratitis
-chlamydia can have asymptomatic carriers; lies dormant in various parts of body
-mycoplasma can have asymptomatic carriers; unknown significance

Question 9

How is feline conjunctivitis diagnosed?

Answer 9

-cytology of conjunctival scrapings to look for inclusion bodies; Chlamydia and Mycoplasma
-PCR test of conjunctival scrapings for resp. panel
-conjunctival culture for Mycoplasma
common to not get a definitive dx

Question 10

What is the treatment for herpes?

Answer 10

-usually self-limiting
-lubricants can abate clinical signs
-antiviral therapy used for refractory or recurrent cases

Question 11

What is the treatment for chlamydia?

Answer 11

*topical antibiotic therapy:
-tetracycline
-erythromycin
-chloramphenicol
-fluoroquinolones

Question 12

What is the treatment for mycoplasma?

Answer 12

topical tetracycline or erythromycin

Question 13

When is empirical oral treatment done in conjunctivitis cases?

Answer 13

*if URI is also present
-tetracyclines or azithromycin

Question 14

What are the clinical signs and history of herpetic keratitis?

Answer 14

-manifests in adults following initial URI and conjunctivitis as a kitten
-keratitis
-dendritic ulceration
-concurrent conjunctivitis
-dry eye development possible; rare

Question 15

How is herpetic keratitis diagnosed?

Answer 15

-dendritic ulceration is pathognomonic
-history of URI in cat with keratitis should arouse suspicion
-PCR test of conjunctival swab

Question 16

Which antiviral drugs are used for herpetic keratitis treatment?

Answer 16

-cidofovir*
-famciclovir*
-ganciclovir
-idoxuridine
-trifluridine

Question 17

What are the characteristics of herpetic keratitis antiviral drugs?

Answer 17

-all antiviral drugs used are nucleic acid analogs; proteins that the virus cannot use are produced
-all topical drugs are capable of inducing chemosis due to sensitivity to the drugs
-want to treat with antivirals for 2 weeks after resolution of clinical signs

Question 18

Which treatments are used for herpetic keratitis besides antiviral drugs?

Answer 18

-topical antibiotics for concurrent bacterial infections
-oral lysine to decrease frequency and severity of recrudescence episodes
-topical atropine if ulcer is present
-lubricants if STT is low
-decrease stress in environment

Question 19

What is the prognosis for herpetic keratitis?

Answer 19

-response to antivirals is pretty good
-recurrence is very common
-must warn owners of recurrence possibility

Question 20

what are the characteristics of a feline corneal sequestrum?

Answer 20

-should be suspected if theres a black lesion in/on the cornea of a cat
-area of focal corneal stromal necrosis
-only seen in cats
-predisposed in brachycephalic cats
-diagnosed on clinical appearance alone

Question 21

What is the etiology of feline corneal sequestrum?

Answer 21

-currently unknown
-theories include tear film abnormalities, decreased corneal sensitivity, herpes, and chronic corneal trauma

Question 22

What are the treatment options for feline corneal sequestrum?

Answer 22

*proactive:
-lamellar keratectomy
-possible grafting procedure
-possible 3rd eyelid flap
-subsequently treat as an ulcer
–chosen if patient is painful or if wanting a predictable outcome

*conservative:
-give sequestrum time to slough spontaneously
-treat subsequent ulcer
-antibiotics if ulcerated
-analgesics if painful
–unpredictable time frame and ulcer depth; not good for painful patients

Question 23

What are the characteristics of eosinophilic keratitis?

Answer 23

-keratitis syndrome of pinkish fleshy proliferation and multifocal white to yellow clusters of cells at limbus and into cornea
-unknown etiology; herpes relation suspected
-diagnosed through cytology; one eosinophil enough to diagnose
-responds to steroids
-may require long term or lifelong treatment with topical immunomodulators

Question 24

What are the characteristics of feline acute bullous keratopathy?

Answer 24

-rapid formation of corneal edema with large fluid pockets in the cornea
-associated with topical and systemic steroid use and systemic cyclosporine
-break in Descemet’s membrane may be seen on ultrasound
-can lead to corneal rupture rapidly
-not a corneal melt; no neutrophil involvement, just edema
-treated via tamponade with a third eyelid or conjunctival flap

Question 25

What are the characteristics of eyelid agenesis?

Answer 25

-congenital absence of portion of lid -typically superotemporal -exposure and trichiasis can lead to keratitis -also present with blepharospasm -can be seen concurrently with other internal congenital ocular anomalies -medically treated with topical lubricants -surgically treated with grafting procedures to try and restore eyelid margin