1. Chapter 4 Common Diseases of Companion Animals
Pupil Iris Sclera Conjunctiva
Ophthalmic Diseases
Chapter 4
Common Diseases of Companion Animals

2. Conjunctivitis
Causes (in dogs, usually not caused by infectious agent)
Allergy (atopy)
Anatomic (ectropion, entropion)
Bacterial infection (predisposed by):
Injury
↓Tear production
Foreign body
Causes (in cats, it is usually infectious)
Feline herpes virus (most common cause of bilateral conjunctivitis)
Calicivirus
Chlamydia psittaci bacteria
Mycoplasma

3. Conjunctivitis Signs Dx Redness Chemosis (swelling of conjunctiva)
Ocular discharge (tears, mucus) Dx
Determine 1º disease, if any
r/o FB
r/o ‘dry eye’ in recurrent cases
Schirmer tear test
1 min; tears show as blue dye

4. Conjunctivitis Rx Client info Topical antibiotic ointment
neomycin/bacitracin/polymyxin B
Gentamicin ophthalmic ointment
Antibiotic w/ cortisone (if cornea is intact)
Client info
Do not allow dogs to ride with head out window
Keep medial canthus of eye clean (warm water, clip hair)
Vaccinate kittens to prevent URI
Do not touch eye with applicator
Discard unused medication

5. Epiphora Causes (2 causes) Overproduction of tears
Excess tearing
Causes (2 causes)
Overproduction of tears
Ocular pain, irritation (from hair, etc)
Faulty drainage by lacrimal system
Blockage of duct (swelling, inflam)
Blockage of puncta (hair, debris)
Imperforate puncta (no opening)
Cockers
Poodles
Trauma

6. Epiphora Signs Dx Rx Client info Watering of eye Discoloration of hair
Fluorescein dye test
Dye at nose shows duct is open Rx
Treat 1º cause
Flush lacrimal ducts
Surgically open imperforate puncta
Topical antibiotic ointment
Keep hair trimmed around eyes
Client info
Hair acts as wick
Staining due to pigment in tears, not blood
Some dogs have life-long problem

7. Entropion Causes Signs
Eye lids rub against cornea; common in dogs, not in cats
Causes
Congenital—large orbits w/ deep-set eyes (poor lid support)
Collies, G Dane, I Set, Dobe, G Ret, Rott, Weim
Poor ocular muscle development (also congenital)
Chesapeake, Labs, Chow, Sam
Trauma → scarring with distortion of lid
2º to painful corneal lesion, conjunctiva inflammation (most common cause in cats)
Signs
Epiphora (tearing)
Chemosis (swelling of conjunctiva)
Conjunctivitis
Pain
Corneal ulceration (±)
Photophobia

8. Entropion Rx Surgical correction is TOC
Temporary mattress suture to evert eye (young animal)
Lateral canthoplasty (to shorten eye lid)
Remove elliptical piece of tissue from under eye

9. Ectropion Causes Signs Rx Congenital Conjunctivitis Epiphora
Bassets, Blood, C Span, E Bull, St Bern
Signs
Conjunctivitis
Epiphora
Keratitis (corneal inflammation/scarring), usually from exposure
Purulent exudate Rx
Surgery to shorten eye lid
Other procedures

10. Hypertrophy of Nictitans Gland (Cherry Eye)
Nictitating membrane is the 3rd eyelid; is a protective structure
Produces ~30% of tears
Cause is unknown
Bassets, Beagle, B Terr, C Span
Signs
Young dog (<2 y)
Epiphora
Usually no pain Dx
r/o tumor Rx
Sx remove gland
Stitch back in place

11. Glaucoma
Aqueous humor provides nourishment to lens and cornea
Increased intraocular pressure; → Blindness
Normally, the amt of fluid produced = amt of fluid leaving eye
Normal: Dog/Cat—12-22 mm Hg
Causes
Inherited (C Span, Basset, Chow)
Secondary—obstruction of drainage angle
Neoplasia
Luxation of lens
Hemorrhage
Uveitis
Signs
Ocular pain
Episcleral injection
Corneal edema
Dilated pupil (unresponsive to light)
Blind (±)

12. Glaucoma Dx Rx IOP>30 mm Hg
Acute (this is an emergency; prevent blindness)
Latanoprost (Xalatan 0.005%)
Facilitates aqueous outflow
Dichlorphenamide (Daranide)
Decreases aqueous production
Surgical
Cryosurgery or laser (destroys part of ciliary body)
Chronic
Enucleation to relieve pain
Schiotz Tonometer
Tono-Pen

13. Ulcerative Keratitis (Corneal Ulcers)
Ulcers usually heal within a few days
Causes
Trauma
Chemical burns
Foreign objects
KCS (Keratoconjunctivitis Sicca)
Conformational abnormalities
Herpes virus (cats)
Signs
Pain
Epiphora
Blepharospasm (eyelid spasm)
Hyperemia of conjunctiva
Dx—Fluorescein dye to cornea
Herpes virus

14. Ulcerative Keratitis (Corneal Ulcers)Rx
Topical atropine (1%) ointment (Debate over benefits and how long to use)
Decrease pain, blepharospasm
Topical broad-spectrum antibiotic ointment
Viral ointments or solutions (Viroptic)
Surgery
Eyelid flap, conjunctival flap
Serum (autologous)
Blocks proteases released from leukocytes and bacteria (helps prevent continued collagen loss)
keep in refrigerator (throw out after 72 hours)

15. Ulcerative Keratitis (Corneal Ulcers)
Client info
Most ulcers heal quickly with treatment
Avoid using old medications
Rx with cortisone will retard healing of ulcer
Do not touch eye with ointment applicator

16. Chronic Superficial Keratitis (Pannus)
Pannus—superficial corneal vascularization/scar tissue
Progressive, bilateral, can result in blindness
Cause
Thought to be immune-mediated
(Infiltration of cornea with lymphocytes, plasma cells)
Animals living above 5000 ft elevation most susceptible
Increased ultraviolet light increases incidence
Signs
Opaque lesions that begin at limbus and extend into cornea
Milky, pink, or tan

17. Chronic Superficial Keratitis (Pannus)
Breeds
G Shep, B Collie, greyhound, S Huskie Dx
r/o KCS, corneal ulcers Rx
Corticosteroids for life
Client info
No cure
If Rx is stopped, disease will return and progress
High altitudes and ↑sun predispose animals

18. Deep Corneal Ulcer
Desmetocele – erosion to membrane

19. Keratoconjunctivitis Sicca (KCS)
Lack of tear production; tears clean, lubricate, nourish, ↓bacteria, aid in healing
Tears from 2 glands: 70%--Lacrimal gland; 30%--Nictitans gland
Signs
Recurrent conjunctivitis, corneal ulcers, keratitis
Dull, dry, irregular cornea, conjunctiva
Tenacious, mucoid ocular discharge
Blepharospasm
Crusty nares Rx
Tear stimulation—cyclosporine, pilocarpine
Artificial tears
Client info
Px is guarded for resolution
Failure to treat → blindness

20. Cataracts Cause Rx Client info Genetic 2º to: Surgical removal of lens
Opacity of lens that causes reduced vision; most common disease of lens
Cause
Genetic
2º to:
Diabetes mellitus (bilat; within 1 y of disease; ↑glucose → ↑fluid in lens)
Most common cause
Trauma (unilateral; HBC, thorn penetration, shotgun pellet)
Lens luxation
Nutritional deficiency
Uveitis
Hypocalcemia
Electrical shock Rx
Surgical removal of lens
Treat underlying cause (e.g., Diabetes)
Client info
Most cataracts are inherited, so don’t breed affected dogs
Dogs can live quality lives even with bilat cataracts

21. Cataracts Signs Dx Progressive loss of vision Opaque pupillary opening
Must be distinguished from senile nuclear sclerosis
Normal old age change; graying of lens; bilat; usu does not affect sight

22. Progressive Retinal Atrophy
A group of hereditary disorders causing loss of rods, cones, and/or blood supply
Breeds
T/min Pood, G Ret, I Set, C Span, Schnauz, Collie, Sam, N Elk
Recessive gene isolated in some breeds
Signs—slow onset of blindness
Loss of night vision → loss of day vision → cataracts (±) Dx
r/o metabolic disorders that could cause cataracts
Ophth exam
gray, granular appearance of retina
Hyperreflective retina
Vascular attenuation, optic nerve atrophy

23. Progressive Retinal AtrophyRx
None
Client info
This is an inherited disease
Avoid buying affected breeds
Have ophth exam by board certified ophth to r/o PRA
Blind animals adapt well
Have trouble in strange surroundings
Cats need taurine supplemented food to avoid retinal degeneration

24. Anterior Uveitis Inflammation of uvea Causes
Inflammation/infection – FeLV/FIP, fungal, bacterial
Neoplasia
Trauma

25. Uveitis – Clinical Signs
Blepharospasm
Aqueous flare – increased turbidity of aqueous humor
Miosis of affected eye
Iridal swelling or congestion
Keratic precipitates
Ciliary flush in limbal region
+/- Corneal edema
+/- hyphema

26. Anterior Uveitis – hyphema

27. Anterior Uveitis

28. Anterior Uveitis – keratic precipitates

29. Anterior Uveitis – Treatment
Topical steroids
Topical Antiinflmmatory drugs (ocufen)
Subconjunctival steroids
Systemic steroids
Atropine – dilates eye, decreases pain
Antibiotics – topically +/- systemically

30. Anterior Uveitis – Client Info
Recheck within 3 days
Secondary glaucoma is frequent complication
Prognosis depends on cause
Treat for 2 months regardless of cause – blood-aqueous barrier disrupted for 6 weeks

31. Proptosed Globe Cause Clinical Signs Trauma Conformation
Retrobulbar abscess or neoplasia
Clinical Signs
Protrusion of the globe,
Eyelids unable to close, may be trapped behind globe

32. Proptosed Globe

33. Proptosed Globe

34. Proptosed Globe – Treatment
Lubricate immediately
Reduce the globe into the socket ASAP to reduce trauma to optic nerve
Enucleation if optic nerve severed
Systemic and topical antibitics
+/- Steroids

35. Proptosed Globe