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Infectious bovine keratoconjunctivitis
Infectious bovine keratoconjunctivitis is a highly contagious infection of the eye, which affects both the conjunctiva and the cornea, the transparent part at the front of the eye. It occurs especially in summer, when there are many flies,...
What is it?
Infectious bovine keratoconjunctivitis is a highly contagious infection of the eye, which affects both the conjunctiva and the cornea, the transparent part at the front of the eye.
It occurs especially in summer, when there are many flies, abundant dust and intense sun: conditions that we find every year in Tunisia and throughout the Maghreb.
It is very painful: the animal keeps its eye closed and looks for shade. An isolated case can become an entire herd problem within a few days, particularly in young pastured cattle.
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:
Profuse tearing, with a damp streak running down below the eye.
Eye closed or half-closed, blinking repeatedly, the animal flees the light and goes into the shade.
Redness of the conjunctiva and vessels visible on the surface of the eye.
Appearance of a whitish or bluish area in the center of the cornea: the eye clouds over, vision decreases.
In advanced cases, a crater develops in the center of the cornea and the eye can become completely opaque.
Only one eye is affected at first, the other may follow.
Reduced appetite, weight loss and stunted growth in young people, who see poorly and move less towards the trough and water trough.
In a batch, several animals are affected within a few days.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The bacteria mainly responsible is Moraxella bovis, which adheres to the cornea and attacks it, alone or with other germs.
It only causes the disease on an already irritated eye: dust, sandstorms, ultraviolet rays from strong sunlight, tall and dry grass which injure the surface of the eye create the breach.
Some animals carry the bacteria in their secretions without showing signs and maintain contamination of the batch from one season to the next.
Hot and dry season, high population of flies.
Intense sunshine and absence of shade in the courses or enclosures.
Dust, sandy winds, tall, dry, prickly grass.
Young animals: calves and heifers are significantly more affected than adult cows.
Animals with poorly pigmented skin and eyelids, less protected from solar radiation.
High density of animals, grouping around water troughs and shade areas.
Stress, transport, mixing of batches of different origins.
Transmission
Flies play the main role: they land on the secretions of a sick animal then on the eye of a healthy animal, carrying the bacteria from one individual to another.
Direct contact between animals and the sharing of soiled equipment also contribute to the spread.
Favorable conditions accumulate in summer: heat, dust, grouping of animals in the shade or around water points, proliferation of flies.
The introduction of a carrier animal is enough to trigger a series of cases in an unaffected flock.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
An eye that tears and closes must be shown to the veterinarian quickly: the time taken to treat it largely determines the preservation of vision.
The veterinarian examines the eye, assesses the depth of damage to the cornea and looks for other possible causes: foreign body, spikelet, dust, injury, irritation by a product, or general illness accompanied by ocular signs.
Faced with several simultaneous cases, he evaluates the entire batch and looks for what, in the environment, maintains the diffusion.
A sample may be taken in certain situations, particularly when cases recur despite treatment.
Treatment
The treatment is based on an antibiotic prescribed by the veterinarian, applied locally in the eye, by injection under the conjunctiva or generally depending on the severity and the number of animals affected.
Pain treatment is warranted: this condition really causes the animal to suffer.
Protecting the eye from light and flies speeds up healing: shade, sometimes fitting an eye patch or temporary stitching of the eyelids decided by the veterinarian in serious cases.
Affected animals are separated from the group when possible, to limit spread by flies.
Never put a product in an eye that has not been prescribed for this use: certain preparations aggravate an already damaged cornea. Waiting times for milk and meat must be respected and asked to the veterinarian.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Fighting flies is the most effective measure: management of manure and wet areas where they reproduce, suitable means of control chosen with the veterinarian, maintenance of the surroundings of buildings.
Provide shade: trees, shelters, open sheds. An animal that can move into the shade receives less radiation and comes into less contact with others around a single shaded spot.
Limit dust in living areas and on taxiways.
Mow or manage tall, dry grass in grazed areas, which injure the eye surface.
Isolate and monitor newly introduced animals.
Identify and treat the first cases without delay: each untreated sick animal fuels the contamination of the entire batch.
Vaccines exist in some countries, but their effectiveness is inconsistent; they never replace fly control and shade management. Ask your veterinarian what is available and relevant locally.
Possible complications
Deep ulceration of the cornea, which can lead to perforation of the eye.
Permanent white scar in the center of the cornea, with permanently reduced vision.
Loss of vision in one eye, sometimes both in the most severe cases.
Marked growth retardation in young animals, which eat and drink less.
An animal that sees poorly is injured more easily, separates from the crowd and becomes difficult to lead.
When to see a veterinarian
An animal closes one eye, keeps it half-closed or cries profusely.
You see a white or bluish spot appear on the eye.
Several animals from the same batch have runny eyes.
An animal bumps into it, hesitates to move forward or can no longer find the water bowl: the vision has already been affected, call without delay.
An eye that has already been treated does not improve within a few days, or gets worse.
The eye appears hollow, deformed or leaks fluid: this is an emergency.
Prognosis
Treated early, the disease most often heals without after-effects or leaving a small scar without consequences.
Forms seen late leave an extensive scar and reduced vision; permanent loss of an eye is possible in the most advanced cases.
At the flock level, control depends on fly control, availability of shade, and the speed with which early cases are treated.
Frequently asked questions
Why do all my calves have runny eyes at the same time?
Because the disease is very contagious and flies carry the bacteria from one eye to the other within a few days. When several animals are affected simultaneously, it is necessary to treat the sick and act at the same time on flies, dust and shade, otherwise the series continues.
Is it contagious to humans?
No, the bacteria responsible does not affect humans. Hand hygiene remains recommended after handling a sick animal, in particular to avoid transporting secretions to other animals.
Will the animal remain blind?
Not in the majority of cases, if treatment is implemented quickly. A deep and neglected attack can, however, leave an opaque scar and very reduced vision, or even loss of the eye. It’s the delivery time that makes the difference.
What to do while waiting for the vet?
Place the animal in the shade, away from the flock if you can, with water and food within immediate reach. Do not put any product in the eye without a prescription: certain preparations worsen a damaged cornea.
References
FAO — Organisation des Nations unies pour l'alimentation et l'agriculture
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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