21.10: Conjunctivitis and KCS Flashcards
Clinical signs of acute conjunctivitis
- Unilateral or bilateral
- Hyperaemia (redness)
- Chemosis (oedema)
- Swelling/ thickening
- Discharge: lacrimation vs mucoid, purulent / mucopurulent / haemorrhagic
- Mild irritation / blepharospasm
- Occasionally pruritis (e.g. allergic conjunctivitis)
Clinical signs of chronic conjunctivitis
- Thickening due to squamous metaplasia of epithelium
- Hyperpigmentation
- Follicular hyperplasia - esp posterior third eyelid and in conjunctival fornices (more common in young dogs, may need treatment but often resolves spontaneously)
Chemosis (oedema of conjunctiva e.g. in conjunctivitis)
Differentials for purulent ocular discharge
- Foreign body
- Bacterial infection
- Dry eye (KCS) - secondary infections common
Differentials for thick/ tenacious discharge
KCS
Differentials for serous (watery) discharge
- Blocked nasolacrimal ducts (epiphora)
- Anything causing ocular pain (ulcer, glaucoma)
Differentials for haemorrhagic discharge
- Trauma
- Neoplasia
- Coagulopathy
Aetiology of canine conjunctivitis
- Infectious - may be primary or secondary
- Non-infectious - irritants, FBs, allergies
- Secondary to adnexal disease, local ocular disease, other ocular disease
Canine infectious conjunctivitis
Primary infectious conjunctivitis is uncommon in the dog;
* viral infections, e.g. canine herpesvirus-1
* bacterial infection
* parasitic infection e.g. Thelazia, Leishmania spp in imported dogs
* Fungal infection is rare in the UK
Secondary bacterial infection is very common
* Commensal gram +ve irganisms e.g. Staphs, Streps
* Less commonly: E. coli, Bacillus spp., Proteus spp., Pseudomonas spp.
Underlying causes of 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, tear duct infection (dacryocystitis)
Bacterial conjunctivitis
