Bacterial Enteritis in Poultry

What is Bacterial Enteritis?

Bacterial enteritis (BE), also commonly referred to as Dysbacteriosis, Dysbiosis and Small Intestinal Bacterial Overgrowth (SIBO) is a disease observed in poultry which entails extreme inflammation and pathology in the gastrointestinal tract.

Due to similar pathologies in the intestine, bacterial enteritis can commonly be confused with coccidiosis and necrotic enteritis, which are two entirely different diseases (see here for our article on coccidiosis). Misdiagnosis can lead to use of antibiotics or anticoccidials when not needed, which can lead to resistance issues. 

Unlike coccidiosis and necrotic enteritis, bacterial enteritis does not present with identifiying lesions. Different Eimeria species — the worms which cause coccidiosis — produce unique lesions. Necrotic enteritis also has very characteristic pathological signs. As a result, bacterial enteritis can only be diagnosed through an evaluation of gut health.

There are multiple scoring systems around, which give a ranking based on evaluation of a number of parameters. This score is then used to assess how likely the pathology seen is actually due to bacterial enteritis. In coccidiosis and necrotic enteritis, scrapings can be taken and microbiological tests performed to diagnose these pathogens. This is not the case for BE, as it does not have a singular clear cause, but is thought to occur due to a cascade of events which damage the gut health and pre-dispose it to becoming unbalanced. 

What causes it?

Many factors come together to cause BE. A combination of microbial action, bad management, feed and stressors on the gut, such as parasite infections like coccidia and mycotoxins, all contribute.  For instance, infection with coccidia will cause damage to the intestinal lining, and it will become inflamed. This damage to the lining can in turn provide a better environment for commensal bacteria to thrive, which might otherwise not cause any pathology. This enables the bacteria to colonise the gut and cause a number of symptoms. 

Other causes could be infection with a virus or mycobacterium, or an oversupply of nutrients from feed. These again provide an environment which favours bacterial growth. This allows certain bacteria to multiply, throwing the gut microbiota out of balance. Infection with these parasites and pathogens cause damage and inflammation to the gut, leading to poor digestion and absorption of nutrients for the bird, leaving a less functional gut.

It can be difficult to diagnose bacterial enteritis, as it has similar symptoms to many other disease.
It can be difficult to diagnose bacterial enteritis, as it has similar symptoms to many other disease.

How do I know if my poultry have bacterial enteritis?

Typical signs of BE include: 

  • Wet litter
  • Diarrhoea 
  • Stable feed intake when it should be increasing (particularly in growing birds)

However be careful, as these signs are also common to other diseases such as coccidiosis. Necropsy can also show signs of BE, and assessment of these parameters allows diagnosis:

  • Gut tone (flaccidity of wall)
  • Gut wall being thin and weak
  • Inflammation present
  • Blood vessels dilated
  • Excessive fluids
  • Ballooning of gut

It is not necessary for all of these pathologies to be present for a bird to have BE. Similarly, these can also be signs of other diseases/infections. 

A process of elimination allows inference of bacterial enteritis. If birds are clear for coccidiosis, mycotoxins and other typical bacterial infections and carry these signs and pathologies, it is likely that they have BE.

How can I prevent it?

Try to prevent BE by targeting the initial causes: 

Prevent cocccidosis by using anticoccidials in feed, vaccines, routine screening and good housekeeping. 

Prevent an encouraging environment in the gut by ensuring suitable feed not rich in nutrients vital for disease causing bacteria

Reduce gut stressors such as mycotoxins and bacteria using routine testing, ensuring sanitary feed, feeders and drinkers, and not mixing flocks. Good cleaning between flocks and mucking out can also aid with this.

Work on management strategies by ensuring cleanliness, routine testing and screening, and treating diseases to prevent outbreaks. Get any animals found dead necropsied and sick animals looked at by the vet. 

General good gut health can be ensured by reducing general stress to birds and ensuring feed and water is in constant supply. Make sure there are no loud stressors, minimal handling and minimal bullying. 

References: VetWorks Poultry Gut Health Training, Belgium 2018.