NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare.

Farmers are advised to discuss their individual farm circumstances with their veterinary surgeon.

E.coli diarrhoea

What is E.coli?

E.coli is a bacterium that is present in the guts of normal animals. Most types of E.coli do not cause disease, however three types of E.coli are associated with diarrhoea in calves.

One type (known as ETEC) attach to and damage the small intestine and produce a special type of toxin (known as an enterotoxin), the second (EPEC) attaches to and damages the small intestine but do not produce enterotoxins, and the third (EHEC) attaches to and damages the large intestine

Clinical Signs

ETEC:

Young calves (usually <3 days old)

Calves become depressed, don’t drink, dehydrate and die rapidly

Diarrhoea is very watery

EPEC:

Older calves (usually <21days)

Usually not so rapid or as severe as ETEC

Diarrhoea yellow and watery

EHEC

Older calves (around 14 days)

Often bloody diarrhoea

Diagnosis

ETEC

· Age of calf

· Severity and nature of diarrhoea

· Laboratory tests can identify the protein used by bacteria to attach to the gut

EPEC/EHEC

· Difficult to diagnose as signs are very similar to diarrhoea caused by other organisms, and non-disease causing E.coli are present in most faecal samples

· Examination of material from post-mortems can confirm E.coli –related disease

Treatment

· Replacing lost fluids is the most important part of treatment. This can range from oral electrolytes for moderately affected calves to intravenous fluids for severely affected calves.

· Commercial electrolytes are more expensive than the home-made version but in moderate to severe cases they are much more effective

· Antibiotics can help in some cases, but they should be used with caution and if possible sensitivity testing should be undertaken.

Prevention

1) Keep the environment as clean as possible, this refers to the calving yards as well as the calf pens.

2) Single penning of young calves will significantly reduce the spread of diarrhoea

3) Sick calves will pass a vast number of disease-causing bacteria. Disinfection is vital

4) If possible use an all-in-all-out system. This allows pens to be disinfected between batches and prevents disease being passed on to every new calf that enters the building.

5) Ensure good colostrum intake. In herds with problems, feeding bulked colostrum for at least 7 days can significantly reduce the number of cases of scour

6) For ETEC diarrhoea only, vaccination is available. This is given to the mother in late pregnancy. The colostrum then contains antibodies that help prevent ETEC infection. For the best effect colostrum feeding should continue for at least a week

Richard Laven PhD BVetMed MRCVS