Conjunctivitis Flashcards
What are the clinical signs associated with acute conjunctivitis?
- Unilateral or bilateral
- Hyperaemia (redness)
- Chemosis (oedema)
- Swelling/thickening
- Discharge – lacrimation vs mucoid, purulent, mucopurulent or haemorrhagic
- Mild irritation/blepharospasm
- Occasionally pruritis (e.g. allergic conjunctivitis)
What clinical signs are associated with chronic conjunctivitis?
- Thickening d/t squamous metaplasia of epithelium
- Hyperpigmentation
- Follicular hyperplasia – especially posterior third eyelid and in conjunctival fornices
- NB follicular conjunctivitis is common in young dogs; may need treatment but often resolves spontaneously
What are differential diagnoses for a discharging eye?
- Purulent discharge
◦ bacterial conjunctivitis
◦ grass seed FB in conjunctiva
◦ KCS (dry eye) - Thick/tenacious discharge
◦ KCS (dry eye) - Serous (watery) discharge
◦ increased lacrimation due to ocular pain
◦ tear overflow (epiphora) due to reduced nasolacrimal drainage - Haemorrhagic discharge
◦ ocular trauma
◦ coagulation problem
What is the aetiology of canine conjunctivitis?
- Infectious – primary or secondary
- Non-infectious – irritants, FBs, allergies
- Secondary to
◦ Adnexal disease (eyelids, tear film, nasolacrimal duct)
◦ Other ocular disease
‣ Local disease – ulcers, blepharitis, orbital disease
‣ Intraocular disease – uveitis, glaucoma, episcleritis/scleritis
What are causes of canine infectious conjunctivitis?
- Primary infectious conjunctivitis: uncommon in dog
◦ Viral infection, e.g. canine herpesvirus-1
◦ Bacterial infection
◦ Parasitic infection e.g. Thelazia or Leishmania spp – imported dogs
◦ Fungal infection rare in UK - Secondary bacterial infection is very common
◦ Commensal Gram +ve organisms, e.g. Staphylococcus spp, Streptococcus spp
◦ Less commonly: E. coli, Bacillus spp, Proteus spp, Pseudomonas spp
What are underlying causes for conjunctivitis?
- FBs (check under third eyelid!)
◦ Important in small furries e.g. GPs - Irritants e.g. smoke, sand, neomycin
- Allergic e.g. atopic dermatitis
- Adnexal disease
◦ Eyelid and eyelash problems
◦ Tear film problems e.g. KCS (dry eye)
◦ Tear duct infection (dacryocystitis)
What are the clinical signs of KCS?
- Recurrent conjunctivitis that improves with any topical therapy as anything lubricates eye!
- Tacky mucoid-mucopurulent discharge stuck to ocular surface
- Ocular pain
◦ Blepharospasm
◦ Enophthalmos with third eyelid protrusion - “Lacklustre” cornea with distorted Purkinje image
- +/- Corneal ulceration
Corneal changes with chronic KCS
* Corneal vascularisation, fibrosis and pigmentation
* Reduced vision
How can you diagnose KCS? How is it treated?
Diagnosis of KCS
* Schirmer tear test
◦ Quantitative measure of aqueous production
◦ Measures basal and reflex tear production
Treatment of (immune-mediated) KCS
* Progressive disease: early treatment best (before lacrimal tissue is destroyed)
* Lifelong therapy - control not cure
* Tear substitutes - Various false tear preparations in eye drop, gel or ointment formulation
* Tear stimulants (lacrimogenic) - Cyclosporine 0.2% (Optimmune)
* Broad spectrum topical antibiotic to treat secondary infection
What are examples of conjunctival involvement in systemic disease?
◦ Anaemia
◦ Jaundice
◦ Coagulopathy
◦ Neoplasia e.g. lymphoma
◦ Auto-immune disease
What is the diagnostic approach for canine conjunctivitis?
- Hands-off examination: blepharospasm? Nature of discharge? Eyelid conformation?
- STT
- Examine anterior segment with focal light source +/- magnification
◦ Examine cornea and conjunctiva (including under TEL for FB)
◦ Examine eyelids - conformation and margins - Fluorescein dye application
◦ Check for corneal ulcer
◦ Jones test to assess tear duct - Check for intraocular disease e.g. PLR, menace response, distant direct (compare pupil sizes) +/- IOP -> should all be normal if just conjunctivitis
- General examination including skin
What is the treatment for canine conjunctivitis?
- Treat/remove underlying cause
- Topical antibiotic therapy
◦ Fusidic acid (Isathal®)
‣ Licensed product in UK – first choice
‣ Treats Gram +ve organisms most commonly found in canine conjunctivitis (Staph spp, Strep spp)
◦ Chloramphenicol drops/ointment
◦ Other antibiotics based on culture & sensitivity
You are presented with a dog with recurrent conjunctivitis in both eyes. The right eye is shown below. Schirmer tear test readings are 13mm/min in the right eye and 9mm/min in the left eye.
What is the most likely diagnosis?
* Bacterial conjunctivitis
* KCS in the right eye only
* KCS in the left eye only
* KCS in both eyes
* Lower lid entropion
KCS in both eyes
What is the aetiology of feline conjunctivitis?
- Infectious: common
- Non-infectious: as for dogs but less common
◦ E.g. entropion – less common, may be acquired in older cats
◦ KCS much less common, hard to diagnose (normal STT values highly variable), can see qualitative tear film problem - Extension from other ocular disease
- Conjunctival involvement in systemic disease
What are causes of feline infectious conjunctivitis?
- Primary infectious conjunctivitis is common (unlike in dogs):
◦ Chlamydophila felis (bacterium)
◦ Feline herpesvirus-1 (FHV-1) (virus)
◦ Feline calicivirus (FCV)
◦ Mycoplasma felis (bacterium)
◦ Bordetella bronchiseptica (bacterium) - Secondary bacterial infections common
◦ Usually secondary to primary infection (cf dogs – secondary infections also common but usually secondary to underlying problem e.g. adnexa/tear film)
What clinical signs are associated with Feline Herpes virus -1? How is it diagnosed? How is it treated?
Clinical signs vary according to age:
* Kittens and young cats
◦ Bilateral conjunctivitis in conjunction with upper respiratory signs (cat flu)
◦ +/- corneal ulceration
* Adult cats
◦ Unilateral ocular discharge with mild conjunctivitis
◦ History of previous upper respiratory infection
◦ Wide range of other conditions, e.g. corneal ulceration, sequestrum, entropion, eosinophilic keratitis
Diagnosis
◦ History and clinical signs
◦ Conjunctival swab for PCR test
‣ Same technique as for C felis
‣ Swab site of interest i.e. swab cornea, conjunctiva and/or oropharynx
◦ PCR has superseded culture (like C felis)
◦ Care with interpretation:
‣ False negatives common d/t intermittent shedding
‣ False positives common – many cats have been exposed to FHV-1, so positive result could reflect FHV-1 reactivation that is coincidental or secondary to the ocular disease
Treatment
◦ Nursing
‣ Cleaning eyes, nutrition, rehydration
◦ Broad-spectrum antibiotic to prevent/treat secondary bacterial infection
‣ Topical for eyes (e.g. fusidic acid, chloramphenicol)
‣ Systemic for respiratory involvement e.g. amoxycillin-clavulanate
◦ Anti-virals
‣ Topical e.g. ganciclovir 4x daily
‣ Systemic e.g. famcyclovir (expensive) 90mg/kg BID recommended dose
