Enteric Colibacillosis in Sheep and Lambs

Enteric colibacillosis is an intestinal disease caused by certain strains of Escherichia coli (E. coli). In lambs, these bacteria can attach to the small intestine and trigger secretory diarrhea, leading to rapid fluid loss, electrolyte imbalance, weakness, and collapse. Merck notes that the same enteropathogenic and enterotoxigenic E. coli types involved in neonatal diarrhea in calves can also affect lambs, especially in intensive lambing settings.

This problem is most important in newborn and very young lambs. Disease can move fast. A lamb that looked only mildly dull in the morning may be severely dehydrated by afternoon, especially if it is not nursing well or the weather is cold.

Some lambs with E. coli infection show mainly diarrhea. Others, especially neonates, may develop a septic or endotoxemic picture often described in practice as watery mouth disease, with depression, weakness, abdominal distension, poor suckle, and shock. That is why any young lamb with diarrhea, weakness, or failure to nurse should be treated as an emergency and examined by your vet.

The direct cause is infection with disease-causing strains of E. coli. These bacteria are commonly present in the environment and in manure, so exposure alone is not unusual. Trouble starts when a vulnerable lamb encounters a high bacterial load or lacks enough early immune protection from colostrum.

The biggest risk factor is failure of passive transfer, meaning the lamb did not receive enough good-quality colostrum soon after birth. Merck emphasizes that neonatal diarrhea control depends heavily on maternal antibodies passed through colostrum. Lambs that are chilled, slow to stand, born after a difficult delivery, or competing in large litters are more likely to miss that early protection.

Management also matters. Dirty lambing jugs, contaminated udders, reused bottles or stomach tubes, crowding, cold wet bedding, and prolonged lambing seasons all increase environmental contamination. Intensive lambing systems and shed-lambing can allow infectious agents to build up quickly. Stress from cold weather, starvation, or poor milk intake can make infection more severe.

Not every diarrheic lamb has enteric colibacillosis. Rotavirus, coronavirus, cryptosporidia, coccidia, salmonellosis, and clostridial disease can look similar. Your vet may need to sort through several possibilities before deciding what is most likely in your flock.

Diagnosis starts with the basics: the lamb's age, how quickly signs appeared, whether it nursed well after birth, and what is happening in the rest of the flock. A very young lamb with sudden watery diarrhea, weakness, and dehydration in a contaminated lambing environment raises strong concern for E. coli-associated disease, but your vet will still consider other neonatal diarrhea causes.

Your vet may perform a physical exam, hydration assessment, temperature check, and review of colostrum intake and lambing-pen hygiene. In flock outbreaks, the pattern matters. Several lambs becoming ill in the first days of life points toward management and infectious pressure, not an isolated digestive upset.

Testing may include fecal sampling, bacterial culture, necropsy of a freshly deceased lamb, and sometimes additional lab work to look for mixed infections. Merck notes that the diagnostic approach in lambs is similar to neonatal calf diarrhea workups, where identifying the likely pathogen and correcting fluid and electrolyte losses are both important.

In real-world farm practice, your vet may begin treatment before every test result is back, because dehydration and shock cannot wait. A practical workup often combines immediate supportive care with targeted diagnostics to guide flock-level prevention.

Prevention starts with colostrum. Newborn lambs need enough high-quality colostrum quickly after birth so they can absorb protective antibodies while the gut is still able to take them up efficiently. Lambs that are chilled, weak, born to first-time ewes, or part of twins or triplets deserve extra attention because they are more likely to fall behind.

Cleanliness is the next big piece. Merck recommends keeping yards, pens, ewes, and equipment as clean as possible during lambing to limit E. coli buildup. That means dry bedding, frequent pen turnover, clean udders when possible, sanitized bottles and tubes, and avoiding overcrowded jugs where manure contamination rises fast.

Good general lambing management also lowers risk. Reduce cold stress, make sure lambs nurse promptly, separate sick lambs, and avoid prolonged use of heavily contaminated lambing areas. In flocks with repeated neonatal diarrhea, your vet may review ewe vaccination timing for the broader neonatal diarrhea complex, colostrum handling, and whether a diagnostic workup is needed to identify mixed infections.

If several lambs are affected in one season, think beyond the individual case. A flock-level prevention plan with your vet is often the most cost-effective path. Small changes in colostrum monitoring, sanitation, and pen flow can make a meaningful difference in losses.