Ben Crisp BVSc MRCVS from Chicken Vet considers how to manage this common condition.

Diarrhoea is the most common complaint from keepers of domestic poultry and I will try and explain how to recognise the different types before guiding you on to the appropriate treatment.

Diarrhoea in mammals is defined as the increase in faecal water content and often a small increase of 5% will produce signs of loose faeces. However, life is not that simple for birds!

Mammalian water and salt regulation is predominantly done by the renal system with only a very small part played by the large colon. In birds, the kidneys are more basic and have limited salt handling capacity and can probably only concentrate the kidney output by twofold. This means that birds have adapted other measures to help control water and salt handling. A lot of water regulation is done by the distal intestinal tract as this receives water from the proximal intestines and from the kidneys via the cloaca.

This is important to know because a watery output from a bird cannot be defined in the true sense, as if there is an increase in renal output then this will also produce loose faeces. The hind intestine has more water regulation involvement so more minor disturbance in intestinal integrity or solute pressure will produce watery faeces. So, this is more likely to dehydrate birds and cause acid base unbalances quicker than in mammals.

What is normal?

There are two types of normal faeces; one is a solid formed ball with a white ‘cap’ on top formed by the urates. The second is referred to as a caecal dropping which tends to be a bit looser with a chewed toffee type consistence and colour, often without any urate component. This represents the voiding of one of the caecal tonsils. You would normally expect a couple of these per day but it should not be the predominant type as this suggests a motility disturbance.

Physiology of diarrhoea

As the intestinal tract is very short in birds, to maximise its efficiency the intestinal contents is moved up and down the length of the intestinal tract several times before being voided. This is under very tight neurological control from the central nervous system but also from local pacemakers in the intestines. One of the most important control areas is the gizzard and ventriculous. If this is disturbed then this will cause the intestine to void too quickly giving undigested food but also add higher levels of protein and starches into the hind intestines which will cause increase in fermentation, alter the pH and cause a shift in the resident bacteria towards more pathogenic population such as Clostridia spp. This causes damage to the intestinal integrity and disrupts the normal homeostasis mechanisms for water regulation causing diarrhoea.

Kidney dysfunction will produce a polyuria and when voided into the cloaca is very difficult to distinguish from intestinal disturbance but will often go hand in hand with each other. The kidneys are easily overwhelmed due to the limited ability to concentrate the urine and we often see diarrhoea in a situation referred to as purging. This occurs if salt and mineral levels are fed at too high a level, which may have been intentional to encourage drinking in a flock or unknown, as some borehole waters can be very high in soluble salts and minerals which can change on a daily basis.

There are a few primary kidney diseases in birds and one of the most common is an infectious bronchitis virus which is specifically adapted to attack the renal system. Secondary kidney diseases include tumour attack of the kidneys due to Marek’s and reticuloendotheliosis virus. System wide inflammation will affect the kidneys and is often seen with influenza and Newcastle disease.

Causes of disturbances

Yellow frothy diarrhoea


Often this is an over fermentation in the hind gut and is most commonly caused by a bacterial disturbance, usually an inappropriate diet or stress causing a maldigestion. This is usually easily resolved but probiotics can be very useful.

Undigested food (Weetabix looking) 


Again, this is normally an environmental or stress response and does not cause a problem to the bird as is usually self-resolving. If allowed to continue it may lead to frothy or more watery diarrhoea. Increasing fibre and grit into the diet usually helps to slow down the intestinal transit.

Watery white 


This can be due to complete anorexia and only has the urate/urine component but if it is very watery it could be caused by kidney disease, and if transient can be due to purging. This kind of faeces may not be a primary intestinal problem and will often involve other clinical signs if looked for.             



This is a more advanced form of intestinal inflammation and usually represents mucosal casts or proximal intestinal inflammation. It is often seen in young birds with certain forms of cocci but can be a more serious bacterial infection causing a necrotic enteritis. Do note that urates/urine in the faeces can react with some wood shavings to produce a pink colouration which is often confused with blood and is completely harmless.

High volumes of watery urine can be due to kidney diuresis, there is no recognisable feed material meaning anorexia, and green staining is bile acids that haven’t been reabsorbed or changed by the action of normal gut bacteria. This type of faeces is often seen in pathogenic virus’ like flu and Newcastle disease. It carries a poor prognosis and, if suspected, is notifiable.


For uncomplicated diarrhoea the aim is to restore normal gut bacterial populations. This can be achieved by using probiotics such as Beryl’s or feeding products which promote the correct bacterial such as Oligosaccharides and various yeast extracts (Intestiflora).

If not already used, the addition of grit to the diet will help with proper digestion and motility of the intestines. The bird’s diet should mainly consist of a commercial diet with added roughage and minimal corn.


There are tannin based products (Biostop) which control the intestinal movement and reduce the supply of amino acids to the hind gut by binding them and will help with frothy and Weetabix type issues.

Antibiotics should only be used if there is evidence of mucosal disruption or if the birds are ill.  


Take ongoing diarrhoea seriously in your birds and always look for apparently unconnected diseases, however most of the time it is simply a management issue.


This article first appeared in Smalholder magazine. Subscribe here or buy from your local newsagent.