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Ovine infectious keratoconjunctivitis
Infectious keratoconjunctivitis is a contagious inflammation of the surface of the eye and its membranes. It affects both the conjunctiva, the pink tissue around the edge, and the cornea, the transparent window in the center. It is due to g...
What is it?
Infectious keratoconjunctivitis is a contagious inflammation of the surface of the eye and its membranes. It affects both the conjunctiva, the pink tissue around the edge, and the cornea, the transparent window in the center.
It is due to germs which are transmitted very easily from one animal to another, carried by flies, by runoff and by the simple contact of heads with the trough or rack.
Its evolution is spectacular: a clear eye in the morning can be white and closed the next day. The cornea becomes cloudy, then frankly opaque, and the animal can no longer see.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
First sign: profuse tearing, with a wet streak that runs down the cheek and sticks to the wool.
Half-closed eye, animal that blinks, that flees the light, that keeps its head in the shade.
Marked redness around the eye and swelling of the eyelids.
Third eyelid visible in the corner of the eye, pink membrane which partially covers the surface.
Appearance of a bluish or whitish veil on the cornea, which spreads over one or two days and makes the eye opaque.
Red vessels appear on the surface of the cornea, progressing from the edge towards the center: this is a sign of healing in progress, not worsening.
Discharge initially clear, then thick and yellowish when a secondary infection sets in.
In severe cases: corneal ulcer, bulging eye, sometimes perforation.
Animal that bumps into itself, hesitates, no longer follows the herd, turns in place.
Loss of appetite and rapid weight loss in animals affected by both eyes, which can no longer find the trough.
One or both eyes; several animals in the herd affected in a few days, which is very characteristic.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Specific germs from the eyes of small ruminants are responsible; some are particular bacteria, others belong to neighboring families.
Carrier animals, without any signs, harbor these germs in their eyes and spread them to the herd: this explains the apparently causeless outbreaks.
Flies play a major role in transporting secretions from one eye to the other, which explains the summer seasonality.
Anything that irritates the eye facilitates the installation of germs: dust, thatch, grain awns, tall and dry grass, sand blows, ammonia from a poorly ventilated sheepfold, transport in a cattle truck.
Promiscuity at the trough, rack and water points puts the heads in direct contact and spreads the disease.
Stress, gatherings, transport and fairs precipitate outbreaks.
Bright light aggravates the pain and causes animals to huddle in the shade, which further increases contagion.
Hot season and high fly pressure.
Dust, sandstorms, stubble, tall and dry grass, transport in cattle trucks.
Promiscuity at the trough, the rack and the water points, overdensity in the sheepfold.
Poorly ventilated sheepfold and loaded with ammonia.
Groupings, fairs, quarantine-free purchases, transhumance returns.
Young animals and stressed animals, more sensitive.
Lack of shade, which pushes animals to huddle together.
Herd where a first case was not isolated quickly.
Transmission
The disease is very contagious between sheep and goats. It is transmitted by eye secretions, directly from one head to another or via flies.
Restraint equipment, troughs, racks and the breeder's hands can also carry germs.
Carrier animals without visible signs introduce the disease into an unaffected herd: an animal purchased and integrated without quarantine is the classic route of entry.
Gatherings, fairs, transportation and common pastures multiply the opportunities.
There is no transmission to humans under normal working conditions; washing your hands after treating a diseased eye and before touching another animal remains essential, so as not to spread the disease in the herd.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian examines the eye completely: eyelids, conjunctiva, cornea, and looks for a foreign body, a beard of cereal or a seed stuck under the eyelid, which gives exactly the same picture on a single eye.
It uses a dye that reveals corneal ulcers invisible to the naked eye and helps assess severity.
He assesses whether the damage is unilateral or bilateral: a single eye points more towards a foreign body or an injury, both eyes and several animals point towards a contagious disease.
Samples can be taken to identify the germ when the herd does not respond to treatments.
He rules out other causes of eye disorders in sheep: trauma, entropion in young people, foreign bodies, ocular damage from certain general diseases, and especially the causes of blindness of nervous origin, where the eye is perfectly normal and where it is the brain which is affected. This last distinction is essential because it is urgent.
Finally, he evaluates the body condition of blind animals: this is often where the real prognosis comes into play.
Treatment
Many animals recover spontaneously within a few weeks, but treatment significantly shortens the episode, reduces pain and limits the after-effects.
The veterinarian prescribes a local treatment to be applied directly to the eye, and sometimes a general treatment or by injection under the conjunctiva in severe cases or when the herd is widely affected. The product, the form and the rhythm are his prescription.
An anti-inflammatory can be prescribed to relieve pain, but certain products are dangerous in the presence of a corneal ulcer: this is one more reason to never use a leftover bottle intended for another use or another type.
Never apply a product not intended for the eye to a sheep's eye: antiseptics commonly used in breeding, products against flies and homemade preparations burn the cornea and transform an irritated conjunctiva into a lost eye.
The most important point of treatment is not medication: you must ensure that the animal eats and drinks. A blind sheep must be isolated in a small flat enclosure, without obstacles, without a deep water point, with food and water within immediate reach and always in the same place. Without it, he loses weight very quickly.
Putting the animal in the shade really relieves the pain.
Protecting the eye from flies is essential, with a suitable product applied around the eye and not in it, according to the veterinarian's advice.
Isolating affected animals limits the spread, provided you do not leave them alone without monitoring their diet.
Respect the waiting times indicated for the products used.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Quickly isolate the first affected animals: an outbreak occurs in the first days.
Control flies during the hot season, around animals and in buildings.
Provide sufficient shade so that animals are not forced to huddle together.
Increase trough length and number of watering points to reduce head-to-head contact.
Properly ventilate the sheepfolds, limit dust and ammonia, do not overload.
Quarantine any animal purchased and examine it before integration: carriers without signs are the classic route of entry.
Avoid long transports and groupings during the hot season when possible.
Wash your hands after treating an eye and before touching another animal; clean the restraint equipment.
Monitor the herd daily during periods of risk: a watery eye spotted early prevents ten blind animals.
Possible complications
Deep corneal ulcer which can lead to perforation and loss of the eye.
Permanent white scar on the cornea, with reduced vision for life.
Temporary blindness in both eyes, with rapid weight loss, dehydration and sometimes death from starvation if the animal is not assisted.
Accidents among blind animals: falls, drowning in a watering hole, animals lost along the way, predation.
Abortions and drop in production in very weakened females.
Long-term growth retardation in affected lambs.
Outbreak affecting a large part of the herd within a few weeks.
When to see a veterinarian
One eye becomes cloudy, whitish or opaque in one or two days.
Several animals in the herd are crying or keeping one eye closed: act immediately, the disease spreads quickly.
An animal is affected in both eyes and can no longer find the trough or the water trough: it is a situation which puts its life at stake.
The eye bulges, bleeds, or the discharge becomes thick and yellowish.
Only one eye is affected without the other animals being affected: it may be a foreign body, to be removed by the veterinarian.
An animal can no longer see even though its eyes appear perfectly normal: it is a different emergency, of nervous origin, call without delay.
The condition does not improve after a few days of treatment.
Prognosis
Good in the vast majority of cases: most animals regain their sight within a few weeks, with or without treatment, and the treatment shortens the episode.
Reserved when a deep ulcer has formed: a scar may persist and permanently hinder vision.
Bad in case of perforation of the eye, which is then lost.
The real prognostic factor is often not the eye but the body condition: an animal blind in both eyes, without assistance, can die of hunger and thirst even though its eye would be healed in three weeks.
At the herd level, a well-managed outbreak dies down within a few weeks; poorly managed, it passes through the entire herd and costs growth and body condition.
Frequently asked questions
My sheep has a completely white eye, will it return to normal?
Most often yes. The opacity of the cornea generally resolves within a few weeks and the animal regains its sight. A white scar may remain if a deep ulcer has formed. The important thing is to have the eye examined to see if there is an ulcer, as this changes the treatment.
Can I put an antiseptic or fly repellent in my eye?
No, never. Antiseptics commonly used in livestock farming and antiparasitic products burn the cornea and can cause eye loss. Only products intended for the eye, prescribed by the veterinarian, should be applied. Fly control products are applied around the eye, not in it.
My sheep is blind in both eyes, what should I do while waiting for him to heal?
This is the most important question. Isolate it in a small flat enclosure, without obstacles and without deep watering points, with food and water always in the same place and within immediate reach. Check every day that he is eating and drinking. Many animals die of hunger and thirst even though their eyes would have healed on their own.
Why does the disease return every summer?
Because carrier animals without signs keep germs in their eyes, and the hot season brings together all the conditions: numerous flies, dust, animals crowded together in the shade and at the trough. Controlling flies, providing shade and lengthening troughs significantly reduce outbreaks from one year to the next.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 11 August 2026
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