Colibacillosis in Pigs: E. coli Scours, Diarrhea, and Dehydration
- Colibacillosis is an intestinal infection caused by enterotoxigenic E. coli (ETEC) that most often affects nursing piglets and recently weaned pigs.
- Typical signs include sudden watery diarrhea, weakness, rapid dehydration, sunken eyes, and sometimes death before diarrhea is even noticed.
- See your vet promptly if a piglet is dull, not nursing, or losing fluids quickly. Young pigs can decline within hours.
- Diagnosis usually combines age and herd history, exam findings, and testing such as intestinal culture, PCR for virulence factors, or necropsy samples.
- Treatment focuses on fluids and electrolytes first, plus your vet may recommend targeted antimicrobials based on testing and local resistance patterns.
- Prevention often centers on clean farrowing areas, good colostrum intake, reducing chilling and crowding, and sow vaccination before farrowing.
What Is Colibacillosis in Pigs?
Colibacillosis in pigs is a diarrheal disease caused by certain strains of enterotoxigenic Escherichia coli (ETEC). These bacteria attach to the lining of the small intestine and release toxins that pull fluid and electrolytes into the gut. The result is often profuse watery diarrhea, dehydration, and acid-base imbalance, especially in very young pigs.
This condition is seen most often in nursing piglets and recently weaned pigs. In pigs, enteric colibacillosis is considered very common in both the 0-3 week nursing period and the 3-9 week weaning period, while it is uncommon in older growing pigs. That age pattern matters because a piglet with sudden scours is not dealing with the same list of likely causes as an older pig.
For pet parents and small-scale pig keepers, the biggest concern is speed. A small piglet can lose a dangerous amount of fluid in a short time. Even when the diarrhea looks mild at first, dehydration can become serious quickly. Early veterinary guidance can make a major difference in survival and recovery.
Symptoms of Colibacillosis in Pigs
- Watery yellow to pale diarrhea
- Rapid dehydration with tacky gums or dry mouth
- Sunken eyes and gaunt appearance
- Weakness, lethargy, or reluctance to stand
- Poor nursing or reduced appetite after weaning
- Weight loss or failure to gain normally
- Cool body temperature or collapse in severe cases
- Sudden death, sometimes before diarrhea is obvious
Colibacillosis often starts with sudden, watery scours and can progress fast. Some piglets become dehydrated, weak, and acidotic within hours. In severe cases, a pig may collapse or die before diarrhea is clearly seen.
See your vet immediately if your pig is not nursing, seems dull, has sunken eyes, feels cool, cannot stay hydrated, or if more than one pig in the group is affected. Young piglets are at the highest risk because they have very little reserve when fluid loss starts.
What Causes Colibacillosis in Pigs?
Colibacillosis is caused by pathogenic strains of E. coli, especially ETEC strains that carry fimbriae such as F4 (K88), F5 (K99), F6 (987P), F18, and F41). These fimbriae help the bacteria stick to cells in the small intestine. Once attached, the bacteria release toxins that trigger secretion of water and electrolytes into the intestinal tract.
Age matters. Neonatal colibacillosis is commonly linked to F4 and sometimes F5, F6, or F41 strains. Postweaning colibacillosis is more often associated with F4 or F18 strains. Not every pig is equally susceptible, because some pigs do not express the intestinal receptors that certain fimbriae need in order to attach.
Outbreaks are more likely when pigs face stress or poor environmental conditions. Common risk factors include inadequate colostrum intake, chilling, damp bedding, crowding, sanitation problems, abrupt diet changes, and weaning stress. In real life, disease usually reflects a mix of bacterial exposure plus a pig whose immune defenses or environment are not working in its favor.
How Is Colibacillosis in Pigs Diagnosed?
Your vet will usually start with the basics: the pig's age, timing of diarrhea, hydration status, nursing or weaning history, and whether multiple pigs are affected. That history helps narrow the list, because several other conditions can also cause scours in piglets, including rotavirus, coccidiosis, clostridial disease, transmissible gastroenteritis, porcine epidemic diarrhea, and salmonellosis.
A presumptive diagnosis may be made from the pattern of disease, but confirmation is more specific. Merck notes that diagnosis is typically based on a combination of lesion assessment, bacterial culture, and genotyping of isolates, with histopathology showing coliforms attached to the small-intestinal brush border. PCR testing can identify fimbrial and toxin genes, which helps separate harmful E. coli from strains that are merely present in the gut.
In practice, your vet may recommend fecal or intestinal sampling, necropsy of a freshly deceased piglet, culture, and PCR-based virulence testing. This matters because not all hemolytic E. coli are true pathogens, and treatment decisions are stronger when they are guided by testing rather than guesswork.
Treatment Options for Colibacillosis in Pigs
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm or clinic exam focused on hydration and severity
- Oral electrolyte support if the pig is still able to swallow and nurse
- Warming, dry bedding, and separation from stronger pen mates if needed
- Basic fecal or herd-level assessment without full lab work
- Targeted medication plan from your vet when appropriate
Recommended Standard Treatment
- Veterinary exam plus hydration assessment
- Oral or injectable fluid and electrolyte therapy based on severity
- Fecal, intestinal, or necropsy sampling for culture and/or PCR virulence testing
- Antimicrobial selection guided by your vet and, when possible, susceptibility information
- Monitoring for acidosis, weakness, nursing failure, and spread through the group
- Environmental corrections such as sanitation, temperature control, and nursing support
Advanced / Critical Care
- Emergency stabilization and intensive fluid therapy, often IV in severe cases
- Hospitalization or close inpatient-style monitoring for weak, collapsed, or non-nursing pigs
- Expanded diagnostics such as necropsy, histopathology, culture, PCR virulence testing, and differential testing for viral or parasitic causes
- Frequent reassessment of hydration, temperature, glucose support, and acid-base status
- Group-level outbreak planning with your vet for treatment, isolation, sanitation, and prevention
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Colibacillosis in Pigs
Bring these questions to your vet appointment to get the most out of your visit.
- Does my pig's age and history fit E. coli scours, or are other causes more likely?
- How dehydrated is my pig right now, and does it need oral fluids, injectable fluids, or hospital care?
- Should we submit fecal, intestinal, or necropsy samples for culture or PCR testing?
- If medication is needed, how are you choosing it, and do you recommend susceptibility testing?
- What signs mean this has become an emergency, especially overnight?
- How should I clean and manage the pen to reduce spread to other pigs?
- Could poor colostrum intake, chilling, or weaning stress be contributing in this case?
- Would sow vaccination or a herd prevention plan make sense for future litters?
How to Prevent Colibacillosis in Pigs
Prevention starts with lowering both exposure and stress. Good sanitation in farrowing and nursery areas matters, but so do basics like keeping piglets warm, dry, and able to nurse well. Dampness and cold are recognized predisposing factors, and pigs under environmental stress are more likely to get sick when pathogenic E. coli is present.
Strong early immunity is also important. Piglets need prompt access to adequate colostrum, because maternal antibodies help protect the gut during the highest-risk period. Avoiding overcrowding, reducing abrupt feed changes, and managing weaning carefully can also lower the chance of postweaning disease.
Vaccination can be part of a prevention plan. Merck lists sow vaccination for colibacillosis at 5 and 2 weeks before first farrowing, and 2 weeks before each subsequent farrowing for herds at higher risk. Your vet can help decide whether that schedule fits your situation, especially if you have repeated scours in litters.
If diarrhea keeps recurring, prevention should move beyond cleaning alone. A herd-level review with your vet may include housing, temperature, colostrum management, stocking density, feed transitions, and targeted diagnostics to confirm whether ETEC is truly the main problem.