Diarrhea by E. coli affects mainly lactating piglets, causing high mortality.

Alternative names: E. coli Diarrhea


Of all the diseases in piglets, diarrhea is the most common, and the most important. In some outbreaks mortality and morbidity are high. In well managed farms, less than 3% of the litters should need treatment at a given point in time and the mortality should be lower than 0.5%. In very severe outbreaks, mortality can be higher if litters are not treated.

The main causes of diarrhea in piglets are: E. coli, clostridium, coccidia, TGE virus, porcine epidemic diarrhea virus, rotavirus, and agalactia. E. coli is the most common.

When piglets are born, the gastrointestinal tract is microbiologically sterile and has low immunity to fight organisms causing disease. These organisms rapidly colonize the digestive tract after birth; amongst these organisms, strains of E. coli and Clostridium are potentially pathogenic. Immunity is initially obtained through colostrum, which contains high antibody levels (IgG and IgA). After being absorbed, colostrum antibodies enters the blood stream and the immunity is maintained through antibodies (IgA) present in milk (lactogenic protection). It is of paramount importance for newborn piglets to drink colostrum immediately after birth to avoid pathogenic organisms multiplying in the intestinal wall, causing diarrhea. It is also very important for the piglet to drink milk continuously, in order to keep the intestine covered with protecting antibodies (IgA).

Antibodies acquired in a passive way from colostrum and milk do not last forever and can be exceeded by the bacterial loads present in the environment. As the number of organisms ingested increases, the risk of disease increases. Environmental stress such as cold also has an important role because it decreases the piglets resistance. There is a delicate equilibrium between the level of antibodies and the infectious load together with stress.

In piglets younger than 5 days of age, the most common cause of acute diarrhea is E. coli, mainly in first parity sows. Clostridium infections are also produced at this age.

At weaning, the loss of milk intake and IgA, the expression of new intestinal receptors, and intestinal irritation due to change in diet (liquid milk based to dry plant protein) allows E. coli to adhere to the small intestine villi, and its toxins cause acute diarrhea, 5 to 14 days after weaning. 


Sows and growers

  • None.

Lactating piglets

  • Acute disease
    • The only symptom can be to find a dead piglet which was in good shape.
    • Piglets get piled up and tremor or lay in a corner.
    • Skin surrounding anus and tail are wet.
    • Watery diarrhea or loose stools.
  • As diarrhea progresses.
    • Dehydration.
    • Sunken eyes.
    • Cardboard like skin.
  • Sub-acute disease
    • Symptoms are similar but the effects on the piglet are less dramatic, last longer and the mortality is lower.
    • This kind of diarrhea can be observed more frequently in piglets 7 to 14 days old.
    • Watery diarrhea or loose stools that can be white or yellow.


  • The first symptoms are slight loss of body condition, dehydration and watery diarrhea.
  • In some cases feces can have blood or be dark or loose, and have a wide range of colors: grey, white, yellow and green. The color is not important.
  • Pigs in poor condition– deteriorated, hairy coating.
  • Loose feces, dirty and wet pens.
  • Sunken eyes.
  • Dehydration produces a rapid weight loss.
  • In severe cases, dead piglets with sunken eyes can be found.
  • Also dead piglets in good condition, without any external sign can be found.
  • Occasional vomiting.

Causes / Contributing Factors

Sows and lactating piglets

  • Flooring in bad shape.
  • Bad hygiene of pens, especially associated to bad drainage.
  • Bad hygiene measures between groups.
  • Contamination from one part of the farm to another with for example boots, brushes, shovels, clothes, etc.
  • Continuous animal flow.
  • Humidity, heat, feed leftovers and feces are ideal for bacteria multiplication.
  • Chilling of pigs, especially due to cold airstreams.
  • Routine use of milk replacers, mainly if they get spoiled or contaminated.


  • Based in clinical examination, antibiotic treatment response (viral infections do not respond to treatment), and laboratory analysis of diarrhea samples.
  • Send to the lab a rectal swab, a recently dead piglet or a live one to perform cultures and antibiograms.
  • Identification of E. coli virulent genes using PCR.
  • A very simple test to identify between viral and E. coli diarrhea consists on using litmus paper to determine if the diarrhea is acid or alkaline. Soak the paper in diarrhea; E. coli diarrhea is alkaline (changes to blue), while viral diarrhea is acid (changes to red).


Lactating piglets

  • There are several antibiotics to treat piglets’ diarrhea. Most of them are active against E. coli and Clostridium.
  • Due to the highly contagious nature of the infection the whole litter must be treated as soon as they present the first symptoms.
  • Keep the crate and the area where the piglets lay down and defecate dry.
  • Place an extra lamp as an extra heat source.
  • E. coli diarrhea in litters out of young sows, means low immunity, so we must think on vaccinating the sows. Vaccine must be applied twice, with a difference of 2 to 4 weeks between vaccinations, applying the second dose at least 2 weeks before farrowing.
  • Supply electrolytes in the water to avoid dehydration and maintain electrolytes equilibrium in the body.


  • It is important to know the history of the disease in the farm, and the sensitivity to antibiotics of the bacteria involved. Ill pigs must be treated individually. Add zinc oxide in the weaners diet during 2 to 3 weeks.
  • If the pigs are dehydrated, provide electrolytes in a separate drinker.
  • Oral vaccination of pigs right before or at weaning can be considered.
  • Use of competitive inhibition products can be used to block intestinal receptors from being occupied by E. coli.
  • Water acidifiers can sometimes be effective in lowering E. coli growth in the intestine.