Colibacillosis (E. coli) in laying hens: symptoms, prevention and treatment records
Colibacillosis caused by pathogenic strains of Escherichia coli (APEC) is a common cause of falling egg production and increased mortality in layer flocks. Learn how to recognise egg peritonitis and salpingitis, how to prevent it, and how to keep treatment records with an egg withdrawal period.
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What is colibacillosis in laying hens?
Colibacillosis is a bacterial disease caused by pathogenic strains of the coliform bacterium Escherichia coli — in poultry called APEC (avian pathogenic E. coli). The bacteria themselves are common in the gut and in the house environment, but disease is triggered only by pathogenic strains, usually when the bird’s immunity is weakened and the microclimate is poor. In laying hens the disease usually develops secondarily — after the body has already been weakened by stress, dust, ammonia or a co-infection. Learn more about flock management: Laying hen husbandry.
The key form: egg peritonitis and salpingitis
In layers the most clinically important form of colibacillosis is egg peritonitis and salpingitis (inflammation of the oviduct). Bacteria colonise the oviduct and body cavity, and egg material — instead of travelling to the cloaca — ends up in the peritoneal cavity, where it causes inflammation. So-called internal layers appear — hens that look healthy but have stopped laying, are sluggish and lose condition. In a production flock this means a drop in egg production and gradually rising mortality. Alongside this form, E. coli also causes septicaemia (generalised blood infection) and airsacculitis (inflammation of the air sacs).
How does colibacillosis hit production results?
The most measurable effect is a drop in egg production: sick hens lay fewer eggs or stop laying altogether. On top of that comes poorer overall flock condition, non-uniformity and increased mortality, which in worse cases builds up day by day. Part of the loss is “silent" — hens survive but, as internal layers, add to maintenance costs without producing eggs. Colibacillosis is rarely the primary cause — more often it is the result of a poor microclimate, peak-production stress or co-infections, so its appearance is a signal that something in the house needs fixing.
Why do microclimate and litter matter so much?
Poor ventilation, high ammonia and excessive airborne dust damage the respiratory tract and weaken the bird’s natural barriers, opening the way for E. coli. Wet or caked litter encourages bacterial multiplication and raises dust during scratching. Keeping litter dry and friable and maintaining good air exchange is the basic line of defence. More on litter management: Poultry house litter — management, and on the building itself: House requirements for laying hens.
Colibacillosis and other poultry diseases
Colibacillosis in layers rarely occurs alone. It is favoured by co-infections, especially mycoplasmosis (mycoplasma infection), and by prior respiratory damage from viruses. Peak-production stress, when the hen’s body is heavily loaded by egg laying, further lowers immunity. With a drop in production or rising mortality, always consult a veterinarian and arrange testing. Colibacillosis in other species: Poultry colibacillosis. Symptom overview: Poultry diseases — symptom table.
How colibacillosis hits the layer flock
Each of these signals should prompt the farmer to consult a veterinarian.
Drop in egg production
A sudden or gradual fall in the number of eggs laid is often the first signal of colibacillosis in a production flock. Some hens stop laying entirely, even though they appear healthy.
Internal layers and poorer condition
Hens with egg peritonitis and salpingitis become sluggish, fluffed up and lose weight. They look tired, eat less willingly, and the abdomen may be distended and enlarged.
Increased flock mortality
Mortality rises slowly but steadily — usually single deaths building up day by day. With septicaemia the death rate can accelerate.
Respiratory signs
Airsacculitis causes rapid, laboured breathing and sometimes rales. It is often preceded by respiratory damage from ammonia, dust or a co-infection.
Lethargy and weakness
With septicaemia (generalised infection) hens are apathetic, huddle together, have ruffled feathers and a pale comb. This points to a severe, generalised course.
Changes visible only at post-mortem
Characteristic lesions — peritonitis, deposits on the air sacs, egg material in the body cavity — are seen at post-mortem of dead birds. That is why diagnosis always belongs to the veterinarian.
How to prevent colibacillosis and how to act when disease is suspected
Effective prevention is above all a good microclimate, biosecurity and judicious, documented treatment.
Good ventilation and microclimate
Effective ventilation removes ammonia, moisture and dust, which damage the respiratory tract and open the way for E. coli. Monitor ammonia levels and dust. Details on the building: House requirements for laying hens.
Dry litter and dust control
Keep litter dry and friable through good ventilation, sound drinkers (no leaks) and, where needed, partial litter replacement. Less moisture and dust means lower infection risk. More: Poultry house litter — management.
Gentle management of peak production
Peak production is the period of greatest load on the hen’s body. Avoid abrupt changes of feed, lighting and stocking, and reduce stress and noise. Less peak-production stress means lower colibacillosis risk. See: Laying hen welfare and Layer stocking density.
Farm biosecurity
Consistent biosecurity — entry control, disinfection, protection against rodents and wild birds, clean water — reduces infection pressure and the risk of co-infections that pave the way for E. coli. More: Poultry farm biosecurity.
Treatment by antibiogram
Colibacillosis treatment relies on an antibiotic chosen by antibiogram (a bacterial sensitivity test). This matters because of growing antimicrobial resistance — the antibiotic is selected and prescribed only by a veterinarian. For table eggs a withdrawal period applies: during the egg withdrawal period eggs must not be placed on the market. Help: Veterinarian.
Treatment records and egg withdrawal
Every drug administration must be recorded: date, drug, dose, route and withdrawal period — including the egg withdrawal period. DlaFerm.pl lets you keep these records digitally and track withdrawal dates. More: Treatment records and drug withdrawal.
Frequently asked questions about colibacillosis in laying hens
What is colibacillosis in laying hens?add
It is a bacterial disease caused by pathogenic strains of E. coli (APEC). In layers the key form is egg peritonitis and salpingitis, which causes a drop in egg production, internal layers and increased mortality. The disease usually develops secondarily, when the bird’s immunity is weakened and the microclimate is poor.
Why do hens stop laying eggs?add
With egg peritonitis and salpingitis, bacteria colonise the oviduct and body cavity, and egg material ends up in the peritoneum instead of forming an egg. The hen may look healthy but becomes an internal layer — sluggish, in poorer condition, producing no eggs. This is the main cause of a “silent" drop in flock production.
What favours colibacillosis in the house?add
Most often poor ventilation, high ammonia, dust and wet litter, as well as peak-production stress and co-infections (for example mycoplasma). These factors weaken immunity and damage the bird’s protective barriers, opening the way for E. coli, which is already present in the environment.
How is colibacillosis treated in layers?add
Treatment relies on an antibiotic chosen by antibiogram and prescribed by a veterinarian. It is used judiciously — because of antimicrobial resistance and the egg withdrawal period. At the same time the microclimate must be improved, otherwise the disease will keep returning. Diagnosis and treatment are always set by the vet.
Can eggs from treated hens be sold?add
Not during the withdrawal period. After an antibiotic is given, a defined egg withdrawal period applies, during which eggs must not be placed on the market. The withdrawal period is set by the product leaflet and the vet’s instructions. It is worth recording the end date of the withdrawal period in the treatment records so the date is not mistaken.
How does DlaFerm.pl help with colibacillosis?add
DlaFerm.pl enables digital treatment and withdrawal records — including the egg withdrawal period — the documentation required for every drug administration. The Flock Card lets you track egg production and mortality, making early detection of the problem easier. Data are always available for veterinary or inspection visits.
Sources & resources
Keep treatment records with DlaFerm.pl
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