Cataract
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Emergency presentation is possibleA suddenly cloudy or painful eye requires emergency examination because cataract alone rarely explains acute squinting.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
A cataract is opacity within the normally transparent lens of the eye. Lens proteins and fibres lose their ordered arrangement, scattering light and reducing the image reaching the retina. Cataracts range from tiny focal opacities with little functional effect to mature involvement of the entire lens causing blindness.
Foals can be born with inherited or developmental cataracts, sometimes affecting both eyes. In adult horses, recurrent uveitis is a major cause, while trauma, lens instability and ageing can also contribute. The lens may appear white or blue behind the pupil, but corneal oedema and normal age-related nuclear sclerosis can be mistaken for a cataract from outside.
Vision loss depends on size, position and whether both eyes are affected. A horse may hesitate in dim areas, spook on one side, misjudge obstacles or show no obvious problem in a familiar paddock. Cataract itself is not always painful, but the underlying uveitis and complications such as lens luxation or glaucoma can be very painful.
No eye drop dissolves an established equine cataract. Surgical removal is the only definitive way to restore lens transparency, and success depends on a healthy retina, controlled inflammation and suitable behaviour for intensive aftercare. Small stable opacities may only need monitoring. Prognosis is favourable for selected congenital cataracts treated early, and more guarded when chronic ERU has already damaged the iris, vitreous or retina.
Location matters as much as size: a small central opacity can affect vision more than a larger peripheral one. Congenital cataracts may interfere with development of useful visual pathways in a young foal, while adult cataracts often record previous intraocular inflammation. Lens opacity itself is not always painful, but glaucoma, luxation and active uveitis are.
Screening & Early Detection
A veterinarian examines both eyes after assessing behaviour, menace response and pupillary reflexes. Slit-lamp examination localises the opacity within lens layers and distinguishes cataract from corneal clouding. Pharmacological dilation allows the full lens and retina to be inspected. Tonometry and fluorescein staining identify concurrent glaucoma, uveitis or corneal disease.
When the cataract blocks the fundus view, ocular ultrasound assesses retina, vitreous and lens position. Electroretinography measures retinal function before surgery. Foals with bilateral cataracts receive a wider congenital and genetic assessment; adult horses are evaluated for current or previous ERU.
Standardised diagrams or photographs track progression. Owners should record performance in bright and dim light, but behavioural adaptation cannot quantify vision. A suddenly cloudy or painful eye requires emergency examination because cataract alone rarely explains acute squinting. Prepurchase findings should state size, site, associated inflammation and observed vision rather than treating every tiny opacity as equivalent.
Serial photographs through a dilated pupil distinguish true progression from a change in lighting.
Treatment & Management
A small non-progressive cataract with useful vision may be monitored through regular ophthalmic examinations. Any active uveitis is controlled aggressively because ongoing inflammation promotes cataract progression and damages other structures. A safe consistent environment, good lighting for transitions and warning before approach help a visually impaired horse.
Phacoemulsification removes the opaque lens through a small incision and may include placement of an artificial lens. Candidates need functional retina, manageable inflammation and owners able to provide frequent topical medication and rechecks. Surgery is often most rewarding in young horses with visually significant congenital cataracts before amblyopia or secondary disease develops. ERU-associated adult cases carry higher complication risk.
After surgery, intensive anti-inflammatory and antimicrobial treatment, atropine and activity restriction protect the eye. Complications include uveitis, corneal oedema, glaucoma, retinal detachment and infection. A blind painful eye may require enucleation even when cataract extraction is unsuitable. Horses with stable blindness can retain good quality of life in a predictable hazard-free setting, but riding and turnout decisions must account for bilateral vision, temperament and human safety.
Postoperative medication schedules are planned before surgery because missed early doses can threaten the result.
Breeds or species affected
Akhal-Teke
Open horse breed description, care requirements and conditions
Anglo-Arabian
Open horse breed description, care requirements and conditions
Arabian
Open horse breed description, care requirements and conditions
Barb
Open horse breed description, care requirements and conditions
Caspian
Open horse breed description, care requirements and conditions
Kathiawari
Open horse breed description, care requirements and conditions
Marwari
Open horse breed description, care requirements and conditions
Shagya Arabian
Open horse breed description, care requirements and conditions
Thoroughbred
Open horse breed description, care requirements and conditions
American Quarter Horse
Open horse breed description, care requirements and conditions
American Paint Horse
Open horse breed description, care requirements and conditions
Appaloosa
Open horse breed description, care requirements and conditions
Australian Stock Horse
Open horse breed description, care requirements and conditions
Brumby
Open horse breed description, care requirements and conditions
Waler
Open horse breed description, care requirements and conditions
Morgan
Open horse breed description, care requirements and conditions
Standardbred
Open horse breed description, care requirements and conditions
American Saddlebred
Open horse breed description, care requirements and conditions
Tennessee Walking Horse
Open horse breed description, care requirements and conditions
Missouri Fox Trotter
Open horse breed description, care requirements and conditions
Rocky Mountain Horse
Open horse breed description, care requirements and conditions
Peruvian Paso
Open horse breed description, care requirements and conditions
Criollo
Open horse breed description, care requirements and conditions
Mustang
Open horse breed description, care requirements and conditions
Canadian Horse
Open horse breed description, care requirements and conditions
Andalusian
Open horse breed description, care requirements and conditions
Lusitano
Open horse breed description, care requirements and conditions
Lipizzaner
Open horse breed description, care requirements and conditions
Friesian
Open horse breed description, care requirements and conditions
Dutch Warmblood
Open horse breed description, care requirements and conditions
Hanoverian
Open horse breed description, care requirements and conditions
Holsteiner
Open horse breed description, care requirements and conditions
Oldenburg
Open horse breed description, care requirements and conditions
Westphalian
Open horse breed description, care requirements and conditions
Trakehner
Open horse breed description, care requirements and conditions
Selle Français
Open horse breed description, care requirements and conditions
Belgian Warmblood
Open horse breed description, care requirements and conditions
Danish Warmblood
Open horse breed description, care requirements and conditions
Swedish Warmblood
Open horse breed description, care requirements and conditions
Swiss Warmblood
Open horse breed description, care requirements and conditions
Australian Warmblood
Open horse breed description, care requirements and conditions
Irish Sport Horse
Open horse breed description, care requirements and conditions
Cleveland Bay
Open horse breed description, care requirements and conditions
Württemberger
Open horse breed description, care requirements and conditions
Zangersheide
Open horse breed description, care requirements and conditions
Knabstrupper
Open horse breed description, care requirements and conditions
Orlov Trotter
Open horse breed description, care requirements and conditions
Camargue
Open horse breed description, care requirements and conditions
Icelandic Horse
Open horse breed description, care requirements and conditions
Pony of the Americas
Open horse breed description, care requirements and conditions
Quarter Pony
Open horse breed description, care requirements and conditions
Miniature Horse
Open horse breed description, care requirements and conditions
Clydesdale
Open horse breed description, care requirements and conditions
Shire
Open horse breed description, care requirements and conditions
Percheron
Open horse breed description, care requirements and conditions
Belgian Draft
Open horse breed description, care requirements and conditions
Suffolk Punch
Open horse breed description, care requirements and conditions
American Cream Draft
Open horse breed description, care requirements and conditions
Ardennes
Open horse breed description, care requirements and conditions
Breton
Open horse breed description, care requirements and conditions
Boulonnais
Open horse breed description, care requirements and conditions
Comtois
Open horse breed description, care requirements and conditions
Dutch Draft
Open horse breed description, care requirements and conditions
North Swedish Horse
Open horse breed description, care requirements and conditions
Norwegian Fjord
Open horse breed description, care requirements and conditions
Haflinger
Open horse breed description, care requirements and conditions
Gypsy Cob
Open horse breed description, care requirements and conditions
Irish Draught
Open horse breed description, care requirements and conditions
Welsh Pony and Cob
Open horse breed description, care requirements and conditions
Connemara Pony
Open horse breed description, care requirements and conditions
New Forest Pony
Open horse breed description, care requirements and conditions
Dartmoor Pony
Open horse breed description, care requirements and conditions
Exmoor Pony
Open horse breed description, care requirements and conditions
Shetland Pony
Open horse breed description, care requirements and conditions
Highland Pony
Open horse breed description, care requirements and conditions
Fell Pony
Open horse breed description, care requirements and conditions
Dales Pony
Open horse breed description, care requirements and conditions
Australian Pony
Open horse breed description, care requirements and conditions
Finnhorse
Open horse breed description, care requirements and conditions
Black Forest Horse
Open horse breed description, care requirements and conditions