Diseases of the Eyes and Ears

1. Diseases of the Eyes and Ears INAG 120 – Equine Health Management December 5, 2011

2. The Equine Eye

3. The Equine Eye • Recognize the normal • Ocular – pertaining to the eye • Periocular – area around the eye • Examine eye in bright sunlight or shaded area with flashlight

4. Eye Examination • Overall appearance of head • Erectness of ears • Symmetrical eyelids? • Appearance • Position • Eye Sockets • Assess placement of eyes in sockets • Symmetrical?

5. Eye Examination… • Eyelids • Lightly touch • Symmetrical? • Make note of normal pigmentation of third eyelid • Third eyelid – visiblewhen horse retracts eye into socket

6. Eye Examination… • Anterior Chamber • Space between the cornea and colored portion of the eye (iris) • Filled with transparent fluid • Symmetrical? • Conjuctiva • Mucous membrane lining inner surface of eyelid and outer surface of sclera • Should be moist and shiny

7. Eye Examination… • Iris, Pupil and Lens • Iris = eye color • Pupil (horizontal hole) should constrict with light • Corpora nigra above and below pupil • Pupil should be dark • Posterior Chamber / Eye • “Fundus” • Requires specialinstrumentation • Contains “tapetum”

8. Recognizing the Abnormal • PAIN • Blepharospasm • Photophobia • Epiphora • CHANGE IN COLOR • Redness • Milky-white color • SWELLING

9. Specific Problems of the Eye • Eyelids: • Entropion • Lacerations • Pockets of inflammation • Tumors • Sarcoid • Squamous cell carcinoma • Melanoma • Tetanus/Lockjaw

10. Specific Problems of the Eye • Conjunctiva: • Dermoid • Conjunctivitis • Redness and swelling • Irritating rather than painful • If pain is evident – may be due to another problem • Dirt/foreign materials • Flush with mild eyewash • Squamous cell carcinoma • Angiosarcoma highly malignant

11. Specific Problems of the Eye • Cornea: • Congenital dermoid • Trauma = corneal ulcer • Treatment usually requires antibiotic application • NO STEROIDS • Be sure antibiotic used is Optic • Puncture • Eye will appear partially collapsed • Requires immediate surgical intervention

12. Specific Problems of the Eye • Iris and Ciliary Body: • Uveitis • Iris Cysts • Cause iris to bulge forward • Related to Silver Dapple coat coloration! • Inflammation of iris

13. MICHAEL A. BALL, DVM Classic appearance of long-standing uveitis. Note the scarring of the iris and the white reflective cataract. Recurrent Uveitis • Aka Periodic Opthalmia, Moon Blindness • Clinical signs: • Acute pain • Redness to eyes and lids • Darkened iris • Iris appears moth-eaten • Multiple Causes • Leptospirosis main cause • Onchocerchiasis • Treatments • Complete recovery unlikely

14. Specific Problems of the Eye • Lens: • Flattened, transparent & malleable marble behind the iris (helps focus images • Diseased lens is usually opaque • Cataracts • Progressive in nature • Congenital in foals  more successfully removed

15. Specific Problems of the Eye • Retina/Choroid: • Usually go undetected until blindness is evident • Appaloosas & Congenital Stationary Night Blindness • Autosomal recessive gene • Malfunction of motion-detecting retinal cells (rods) which function best in low light • Day vision = normal

16. When to Call the Vet… • Increased discharge • Squinting and/or excessive blinking • Cloudy appearance • Vision problems • Blood in the eye • Any foreign object inthe eye or eyelids • Any sign of tumor development on the eye or eyelids

17. Do’s • Call the vet early – don’t wait • Only remove a foreign object if it’s confined to the eyelid • Flush dirt, ash, sand or plant material with water or saline • Treat chemicals in eyes as you would humans • Flush with lots of water • Call the vet • Did I mention to call the vet?

18. Don’ts • Don’t ignore eye problems • Be careful using leftover ointment (some ointments can make problems worse) • Triple antibiotic probably ok; avoid atropine or steroid until vet advises • Don’t remove foreign object from eyeball itself, let a vet do it.

19. Head Shaking • Poorly understood disease • Horse may flick, nod and/or shake head • Causes: • Behavioral • Ill-fitting tack • Teeth • Middle Ear disorders • Ear Mites • Eye Disorders • Allergies • Gutteral Pouch Infection

20. Symptoms of Headshaking • Behavior/Ill-fitting tack: • Physical head movements • No disease process (i.e., nasal discharge) • Dental Disease: • Nasal discharge • Foul breath • Pain, swelling over facial bones • Difficulty eating • Abrasions on tongue/cheeks • Weight Loss

21. Symptoms of Headshaking • Gutteral Pouch Infection: • White non-odorous nasal discharge • Swollen lymph nodes • Painful distension of area behind ears • Noisy breathing • Ear Disease: • Rub ears • Sensitive ears • Can be VIOLENT (dangerous for rider/handler) • Head tilt (due to affected balance)

22. Symptoms of Headshaking • Eye Disease: • Cancerous growth • Difficult to catch • Spook easily • Previous slides… • Nasal Disease: • Discharge • Allergies: • Sneezing • Snorting, rubbing nose on legs

23. Photic Headshake • Caused by exposure to light • Overstimulation of eye  stimulation of opthalmic branch of trigeminal nerve  impulses to face • Probably causes sensation in nasal cavity similar to hay-fever sufferers! • Treat by lowering light (fly mask or darkened environment); use of cyproheptidine (0.3 mg/kg BW 2x per day) ± melatonin therapy in summer • Present in spring/summer, worsens with exercise

24. Ear Problems – Aural Plaques • Caused by same virus as warts • Respond poorly to treatment and do not spontaneously regress • Once thought to be caused by biting flies • Can become severely irritated during biting fly season  horses may become defensive about having ears touched! • Soothing ointment such as mentholatum can be helpful; panalogmay also help

25. Warts and Aural Plaques

26. Ear Problems – Middle Ear Infection • Problem in gutteral pouch can migrate • Bacterial or fungal • Doesn’t burst eardrum like other species • Causes fusion of stylohyoid bone and temporal bone of the middle ear • Can lead to stress fractures and neurological problems • Ear rubbing, head tossing, chomping movements, pain around ear, depression, head-tilt, dizzy, facial paralysis

27. Ear Problems – parasites • Most common problem of the equine ear • Chiggers, ticks, and psoroptes mites • Ear mites: • Head rubbing, shaking and irritability • Not always visible • Treat with dewormer and ear drops