Diseases of the Eyes and Ears

INAG 120 – Equine Health Management

December 5, 2011

The Equine Eye

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

Eye Examination Overall appearance of head

Erectness of ears Symmetrical eyelids?

Appearance Position

Eye Sockets Assess placement of

eyes in sockets Symmetrical?

Eye Examination… Eyelids

Lightly touch Symmetrical? Make note of normal

pigmentation of third eyelid Third eyelid – visible

when horse retracts eye into socket

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

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 special

instrumentation Contains “tapetum”

Recognizing the Abnormal PAIN

Blepharospasm Photophobia Epiphora

CHANGE IN COLOR Redness Milky-white color

SWELLING

Specific Problems of the Eye Eyelids:

Entropion Lacerations Pockets of inflammation Tumors

Sarcoid Squamous cell carcinoma Melanoma

Tetanus/Lockjaw

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

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

Specific Problems of the Eye

Iris and Ciliary Body: Uveitis Iris Cysts

Cause iris to bulge forward Related to Silver Dapple

coat coloration!

Specific Problems of the Eye

· Inflammation of iris

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

MICHAEL A. BALL, DVM Classic appearance of long-standing uveitis. Note the

scarring of the iris and the white reflective cataract.

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

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

Specific Problems of the Eye

When to Call the Vet… Increased discharge Squinting and/or

excessive blinking Cloudy appearance Vision problems Blood in the eye Any foreign object in

the eye or eyelids Any sign of tumor

development on the eye or eyelids

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?

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.

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

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

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)

Symptoms of Headshaking

Eye Disease: Cancerous growth Difficult to catch Spook easily Previous slides…

Nasal Disease: Discharge

Allergies: Sneezing Snorting, rubbing nose on legs

Symptoms of Headshaking

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

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; panalog may also help

Warts and Aural Plaques

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

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