Last month, Victoria looked at crop problems and choking in the first of a three-part series on digestive disorders. This month she focuses on diarrhoea.
M any types of Salmonella, only some of which are zoonotic (pass to humans), are present in a large number of wild and domestic birds. Remember that caecal droppings (1:10 to normal ones) are different in colour and consistency from normal droppings.
a) Salmonella pullorum is specific to hens (as well as turkeys and pheasants) and can cause a white diarrhoea and unthriftiness. It used to be known as bacillary white diarrhoea (BWD). It is not as common as it was as carriers (it is passed on through the egg) can be identified by a blood test and culled. Signs may include many dead-in-shell chicks or deaths shortly after hatching, or white faeces stuck to vent feathers and poor growth with pale combs in older birds. The bacteria are also spread in the incubator and rearing units.
Flocks in the DEFRA Poultry Health Scheme are free of pullorum disease due to compulsory use of the blood test, but many backyard flocks still have it, with the organism surviving in the environment for many months.
Treatment is best by culling as any treated birds are liable to be carriers.
b) Salmonella typhimurium and S. enteritidis are zoonotic. It is also possible for humans with salmonella to infect chickens! These organisms appear in the birds at a very young age, causing pasted up vents and a strong smell, ruffled feathers, drooping wings and a high death rate. Faecal contamination of the hatching eggshell is a common source of salmonella infection, so washing all hatching eggs in Virkon (water warmer than the eggs) is a sensible precaution. Vaccination is possible.
Rats and mice are carriers of salmonella, so vermin control is important. Wild birds also carry it, especially flocks of starlings, jackdaws, rooks or blue tits, therefore pelleted feed should be kept inside the hen hut to avoid contamination. If feed is placed outside then only small amounts that can be eaten immediately should be given and access to wild bird table leavings prevented.
c) Nutritional diarrhoea: this may be caused by excess cabbage consumption.
d) E. coli: these bacteria are normal inhabitants (commensal) of the digestive tracts of mammals and birds. In stressful conditions, some strains can cause disease and chicks around three weeks old in overcrowded conditions are susceptible to E. coli infection with a sharp drop in food consumption, followed by listlessness and ruffled feathers. Chick drinkers, therefore, need to be kept scrubbed clean.
e) Campylobacter jejuni has been implicated in intestinal disease of chickens, but is also a commensal and is zoonotic. Good hand hygiene is vital since infected hens do not show illness.