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Calf colibacillosis
Colibacillosis is an infection caused by certain strains of the bacterium Escherichia coli. This bacteria normally lives in the intestine of cattle; only a few specific strains make the calf sick. It is the earliest cause of diarrhea: it ma...
What is it?
Colibacillosis is an infection caused by certain strains of the bacterium Escherichia coli. This bacteria normally lives in the intestine of cattle; only a few specific strains make the calf sick.
It is the earliest cause of diarrhea: it mainly strikes in the very first days of life, often before the calf is a week old.
Two forms coexist. The digestive form gives very abundant liquid diarrhea. The septicemic form, more serious, corresponds to the passage of the bacteria into the blood: the calf sometimes collapses without marked diarrhea.
Key point
A very young calf slaughtered and cold, even without diarrhea, should suggest a generalized infection. Do not wait for the appearance of liquid stools to call.
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:
Digestive form:
Watery diarrhea, very abundant, often pale yellow, appearing in the first days of life.
Rapid dehydration: sunken eyes, persistent skin folds, cold mouth.
The calf suckles poorly then no longer at all, remains lying down.
Septicemic form:
Sudden depression in a very young calf, sometimes without clear diarrhea.
Complete refusal to breastfeed, cold body and ears, pale or grayish mucous membranes.
Fever at first, then temperature dropping — sign of seriousness.
In the days that follow, if the calf survives: swollen and painful joints, infected navel, cloudy eyes, sometimes tilted head and abnormal gait when the meninges are affected.
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 strains of Escherichia coli, capable of clinging to the wall of the intestine of a very young calf and causing a massive leak of water and salts.
The septicemic form occurs mainly in a calf whose defenses are insufficient: the bacteria crosses the barrier of the intestine or the navel and enters the blood.
The common point of these two forms is almost always the same: a calf which has not received enough antibodies through colostrum, in an environment loaded with germs.
Absence or delay in taking colostrum: this is the determining factor, particularly for the septicemic form.
Calving on soiled bedding or outdoors on muddy ground.
Navel not disinfected after birth.
Overloaded building, calves of mixed ages, box reused without cleaning.
Difficult calving having weakened the calf.
Feeding equipment (buckets, teats, probes) poorly cleaned.
Transmission
The bacteria is present in cattle stools and survives for a long time in moist bedding.
The calf swallows it by licking barriers, a soiled udder or bedding, or by drinking from a poorly washed bucket.
It can also enter through the still open navel in the hours following birth, hence the importance of keeping the calving floor clean.
The breeder's hands, boots and equipment carry the bacteria from one box to another.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian first distinguishes the digestive form from the septicemic form: the treatment and the emergency are not the same.
He assesses dehydration, takes the temperature, feels the navel and joints, examines the eyes.
A blood test can measure the level of antibodies received by the colostrum: this is a valuable indicator at the herd level.
A stool or blood analysis can identify the strain in question and test its sensitivity to antibiotics, which avoids ineffective treatment.
In the event of repeated mortality, the autopsy guides prevention for subsequent calvings.
Treatment
Rehydration remains the basis of treatment for the digestive form: it compensates for losses of water and salts and must be started early, according to the veterinarian's instructions.
Unlike viral diarrhea, colibacillosis requires antibiotic treatment in several situations, particularly when sepsis is suspected. The choice of molecule belongs to the veterinarian, ideally guided by an antibiogram.
A calf that can no longer stand up, is cold, can no longer absorb liquids through its mouth: it needs an infusion.
Supportive care accompanies the treatment: anti-inflammatory, warming, dry bedding, isolation.
The treatment must be carried out to the end: stopping as soon as improvement encourages relapses and resistance.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Colostrum is the best protection: given as soon as possible after birth, from a healthy cow, collected properly. The veterinarian specifies the appropriate volume and rhythm.
Disinfect the navel from birth, with a suitable product recommended by the veterinarian.
Calve in a clean, mulched, disinfected area between two cows.
Wash the udder before the first feeding.
Systematically clean and disinfect buckets, teats and probes.
Avoid mixing of ages and overcrowding; clean and let the boxes dry between two calves.
Deal with sick calves last and change gloves or wash hands between animals.
Vaccination
Vaccines administered to pregnant cows at the end of gestation exist against the strains of Escherichia coli responsible for diarrhea in very young calves; they are often associated with rotavirus and coronavirus valencies.
Protection comes only through colostrum: a calf that does not drink it quickly does not benefit from any protection, even if its mother has been vaccinated.
The veterinarian decides on the benefit of vaccination according to the agents identified in the breeding and sets the injection schedule.
Possible complications
Sepsis: passage of the bacteria into the blood, with risk of rapid death.
Arthritis: one or more joints that are swollen, hot, painful, sometimes leaving lasting lameness.
Navel infection, deep abscesses.
Meningeal damage: head tilted, staggering gait, convulsions.
Eye damage, sometimes permanent.
Growth retardation in calves that heal late.
When to see a veterinarian
A calf less than a week old has profuse watery diarrhea: call the same day.
He refuses to breastfeed, he is cold, his ears hang: it's an emergency, the sepsis progresses quickly.
Its mucous membranes are pale or grayish.
His belly button is large, hot or painful.
A joint swells or limps in the days following diarrhea.
Several newborn calves die in a short time: have them analyzed, do not treat blindly.
Prognosis
The digestive form taken early and well rehydrated usually heals.
The septicemic form is much more serious: it leaves little time and the prognosis depends on the speed of treatment.
Calves that develop arthritis or nerve damage often have after-effects.
At the herd level, control comes through colostrum and calving hygiene much more than through treatments.
Frequently asked questions
Why is my calf sick but the mother is healthy?
Because the bacteria normally lives in the intestines of adults without making them sick. It is the calf, whose defenses depend entirely on colostrum, which is vulnerable in its first days.
Should the navel of all calves be disinfected?
Yes, it’s a simple and very profitable gesture. The navel remains an open door for several days, and it is a frequent route of entry to the blood, joints and liver.
Is colibacillosis transmitted to humans?
The strains responsible for calf diarrhea are not those that make humans sick. This does not exempt you from washing your hands after treating an animal: other germs present in the same stools can reach us.
Can I reuse an antibiotic that worked last year?
No. The strains change from one farm and from one year to the next, and a poorly chosen antibiotic delays healing while promoting resistance. The veterinarian uses an antibiogram when possible.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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