21.10: Conjunctivitis and KCS

Question 1

Clinical signs of acute conjunctivitis

Answer 1

• 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)

Question 2

Clinical signs of chronic conjunctivitis

Answer 2

• 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)

Question 3

Answer 3

Chemosis (oedema of conjunctiva e.g. in conjunctivitis)

Question 4

Differentials for purulent ocular discharge

Answer 4

• Foreign body
• Bacterial infection
• Dry eye (KCS) - secondary infections common

Question 5

Differentials for thick/ tenacious discharge

Answer 5

KCS

Question 6

Differentials for serous (watery) discharge

Answer 6

• Blocked nasolacrimal ducts (epiphora)
• Anything causing ocular pain (ulcer, glaucoma)

Question 7

Differentials for haemorrhagic discharge

Answer 7

• Trauma
• Neoplasia
• Coagulopathy

Question 8

Aetiology of canine conjunctivitis

Answer 8

• Infectious - may be primary or secondary
• Non-infectious - irritants, FBs, allergies
• Secondary to adnexal disease, local ocular disease, other ocular disease

Question 9

Canine infectious conjunctivitis

Answer 9

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.

Question 10

Underlying causes of conjunctivitis

Answer 10

• 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)

Question 11

Answer 11

Bacterial conjunctivitis