Coliform Infections and Post-Weaning Diarrhoea

The bacterium E. coli is a common inhabitant of the intestine of the pig. There are two types, non haemolytic and haemolytic, which describe whether or not the organism breaks down blood (haemolysis) on a culture plate. In some countries haemolytic types invariably cause disease due to the toxins that they produce but in others non haemolytic strains predominate. At weaning time the loss of sows milk and IgA allow the E. coli to attach to the villi of the small intestines, the toxins cause acute enteritis and diarrhoea. Post-weaning diarrhoea is a common cause of mortality and morbidity.

Clinical signs

These are usually seen within five days of weaning. In severe cases a pig is found dead with sunken eyes and slight blueing of the extremities. Diarrhoea will not necessarily be seen but in less acute cases the first signs are often slight loss of condition, dehydration and a watery diarrhoea. To identify the latter press the abdomen of a suspect pig and see whether diarrhoea is evident. Dehydration results in rapid loss of weight. The changes in the intestine can be so severe as to cause haemorrhage and blood or black tarry faeces may be seen, but usually the pig dies. The diarrhoea varies in consistency from very watery to a paste with a wide range of colour from grey white, yellow and green. Colour is not of any significance. Fresh blood or mucus would normally be absent.

Diagnosis

This is based on the history of disease in the first week post-weaning although diarrhoea can develop 10 to 14 days post-weaning. Other causes e.g. rotavirus, can give similar symptoms and it is necessary to submit a live or recently dead untreated pig to the laboratory for bacteriological and virological tests to distinguish between them. Determine the antibiotic sensitivity to the E. coli.

Similar diseases

These include porcine epidemic diarrhoea, rotavirus, TGE and salmonella infections. A useful and simple test to differentiate between virus causes and E. coli diarrhoea involves the use of litmus paper to determine whether the scour is an alkaline or an acid consistency. Soak the paper in the scour, E. coli diarrhoea is alkaline (blue colour change) whereas viral infections are acid (red colour change).

Treatment

It is important to know the history of the disease on the farm and antibiotic sensitivities to the bacteria present. Sick pigs should always be treated individually and group treatment applied to the pigs at risk. Ideally by water medication. (Fig.9-22).
Add zinc oxide at a level of 2,500ppm of zinc per tonne. Feed for 2-3 weeks. This is highly effective in controlling E. coli infection.
If pigs become dehydrated, electrolytes should be provided in a separate drinker.

Management control and prevention

The principles of controlling this disease are common to the general management of the post-weaned pig. These are discussed at the beginning of the chapter and you are advised to review these and adjust your control systems as indicated. If there is a problem on the farm use the following checklist:

Pre-weaning

Assess health and body condition of the lactating sow.
Are there respiratory or enteric problems during sucking? Adopt control measures.
Are the weaning problems mainly in gilt litters? If so consider E. coli vaccination.
Are gilts and sows vaccinated against E. coli?
Consider aspects of farrowing house environment and hygiene as discussed in chapter 7.
Creep feeding. Consider the type, frequency and age of introduction.
Stop creep feeding before weaning and assess the effects.

On the day of weaning – consider the significance of:

Stress.
Stocking density – group sizes.
House temperatures and fluctuations.
House hygiene.
Water availability.
Nutrition

After weaning consider:

Air flow.
Temperature fluctuations.
Ventilation, humidity.
Creep feed management.
Response to different creep diets.
Disease.
Age and weight at weaning.
Floor surfaces – comfort boards.
Rate and evenness of growth.