Conjunctival Diseases Flashcards
What is the normal flora of the conjunctiva like in dogs, cats, and horses?
DOGS and CATS - Gram + predominate
HORSES - Gram + and -, fungi
What are the 3 functions of conjunctiva?
- immunologic
- tear film
- barrier
What are the 5 most common conjunctival reactions?
- subconjunctival hemorrhage
- conjunctival hyperemia
- episcleral congestion
- mucopurulent discharge
- chemosis - swelling (or edema) of the conjunctiva
If conjunctivitis is seen on a physical exam, what should be examined?
interpret as a clinical sign —> all ocular diseases can cause it, always perform the big 3 tests
What is the most common conjunctival disease in dogs? What else is seen?
dry eye disease
- bacterial conjunctivitis commonly secondary to dry eye
- neoplasia - papillomas, hemangioma/sarcoma, lymphoma
- allergic
- canine herpesvirus infection
- distemper
What dogs are most commonly affected by conjunctival hemangioma/hemangiosarcoma? What causes its development?
middle-aged, outdoor, Border Collies
UV light exposure
Where is conjunctival hemangioma/hemangiosarcoma most commonly found? What is the treatment of choice?
- third eyelid margin
- conjunctival fornix
- lateral bulbar conjunctiva
- cornea
(non-pigmented areas)
complete surgical excision with possible half removal of third eyelid and cryotherapy
How does conjunctival hemangioma/hemangiosarcoma typically develop?
10% recurrence rate, rarely metastasizes
What do conjunctival viral papillomas need to be differentiated from? How do they typically develop?
SCC, however it is most commonly seen in young animals
spontaneous regression can occur
What are 3 treatment options for conjunctival viral papillomas?
- surgical removal
- cryotherapy
- interferon - immune system related
(remember, spontaneous regression is common!)
What is episcleritis? What are the 2 types and causes of each?
nonpainful inflammation of thin layer of tissue between the conjunctiva and sclera, which looks like blood vessels growing over the sclera
- nodular granulomatous - immune-mediated
- diffuse - tickborne disease
What breeds have a predilection for developing episcleritis? Specifically nodular granulomatous?
- Golden Retriever
- American Cocker Spaniel
Collie and Collie-type breeds
How is episcleritis treated?
topical immunomodulators - steroid and/or cyclosporine
- may bee systemic steroids for severe cases
What are acute and chronic causes of allergic conjunctivitis? What needs to be ruled out?
ACUTE: insect stings, contact with environment allergens
CHRONIC: atopy, environmental allergens - causes lymphatic tissue to form follicles
- dry eye - perform STT
- bacterial infection - cytology
What are 3 treatment options for allergic conjunctivitis?
- topical steroids
- oral antihistamines
- topical antihistamines - Zaditor (OTC option)
What ocular signs are associated with canine distemper virus infection? How is it diagnosed?
- dry eye disease
- conjunctivitis
conjunctival/pharyngeal swabs - IFA for viral DNA detected by PCR
+ point of care ELISA for CPV and CDV for blood samples
What 4 ocular clinical signs are associated with canine herpesvirus infection?
- conjunctivitis
- dendritic corneal ulcers
- conjunctival ulcers
- blepharitis
What dogs most commonly exhibit ocular signs of herpesvirus infection? How is it diagnosed?
mature or juvenile dogs, immunocompromised (thought to only cause severe neonatal fatal disease)
PCR
What are 2 options for treating canine herpesvirus conjunctivitis? What is avoided?
- Ganciclovir gel
- Famciclovir oral
Cidofovir - causes corneal pigmentation
What are 4 general conjunctival diagnostics commonly used?
- Schirmer tear test
- conjunctival cytology
- conjunctival culture - normal flora will grow!
- conjunctival biopsy - incisional, tumor removal
What is the most common cause of feline conjunctivitis? How is it differentiated from other causes?
feline herpesvirus - also causes keratitis (ulcers)
- Chlamydophila felis - IC IB in epithelial cells
- Mycoplasma spp. - “dust particles” attached to epithelial cells
- Calicivirus - oral ulcers
- allergic
- FB
How is feline herpesvirus-1 transmitted? Where does it replicate?
respiratory secretion
conjunctival, nasal, and pharyngeal epithelium
What acute clinical signs are seen with feline herpesvirus infection?
- OCULAR = hyperemia, chemosis, serous to purulent discharge, blepharospasm, corneal ulceration (dendritic)
- SYSTEMIC = sneezing, coughing, nasal discharge, pneumonia
Where does feline herpesvirus undergo neuronal latency? How are cats affected?
trigeminal ganglia
will remain asymptomatic, but stress related to housing changes, steroids, and parturition can cause reactivation of ocular clinical signs
(50% of cats spontaneously shed)
How do the ulcers caused by feline herpesvirus develop?
- EARLY = dendritic/branching
- RAPIDLY DEVELOPS into larger areas commonly affected by secondary bacterial infection and corneal perforation
What chronic clinical signs are associated by feline herpesvirus?
- epiphora
- symblepharon - ulcer forms and heals into an adhesion of conjunctiva to cornea
- KCS
What is pathognomonic of feline herpesvirus infection? How is this seen?
dendritic ulcers stained with Rose Bengal (early) or fluorescein
If ulcers are not seen, how can feline herpesvirus infection be diagnosed?
- virus isolation from swabs of conjunctiva or oropharynx (commonly + in young cats)
- PCR from conjunctival biopsy, scraping, or swab, which is more sensitive and able to detect small amounts of DNA (can be + in non-clinical cats)
What topical and systemic treatment options are available for feline herpesvirus infection?
TOPICAL - Ganciclovir (TID, less irritating), Cidofovir (BID, long half-life)
SYSTEMIC - Famciclovir (BID, 14-21 days, 250 and 500 mg tablets BEST)
In what 3 situations are adjunctive antibiotics needed for feline herpesvirus infection? What is the purpose? Some options?
- corneal ulceration
- other courses of conjunctivitis present
- Mycoplasma and Chlamydophila +
prevent secondary bacterial invaders
- oxytetracyclines (TID-QID)
- erythromycin or chloramphenicol ointment
What are 2 options for adjunctive treatment for feline herpesvirus infection?
- L-lysine - competes with arginine, which the virus needs to replicate
- interferon
(not much evidence, can’t hurt)
What does feline SCC commonly mimic? How does it act?
chronic conjunctivitis or keratitis in cats
locally invasive
