Diagnosing diarrhoea is more complicated than it sounds. There are many factors that can cause diarrhoea.
Diarrhoea is, however, usually the symptom of either an E. coli infection or coccidiosis in many countries.
Note that this advice does not supercede a trained veterinarian’s diagnosis. If possible, seek a trained veterinarian’s advice before proceeding.
A simple faeces (droppings) cheat sheet for farmers/veterinarians: –
Droppings with blood = coccidiosis
Greenish droppings = late stage of worms
White, milky runny droppings = worms, coccidiosis, Gumboro disease (Infectious Bursal Disease)
Brown runny droppings = E. coli infection
Clear or watery runny droppings = stress, Infectious Bronchitis
Yellow & foamy droppings = coccidiosis
Greyish white & running continuously = vent gleet (a chronic disease of the cloaca of domestic birds)
If the above symptoms are not apparent and if the chicken is fairly young (<3 months), treat for coccidiosis first. Ask your local vet for either a toltrazuril or diclazuril oral solution. These are strong coccidiocides and should clear coccidial diarrhoea within a few days. Follow the dosage on the bottle. If the chicken is older, treat for E. coli using Colistin (polymyxin E). Again, ask your local vet for it or an alternative, such as Neomycin. Chicks usually get diarrhoea in the first few days of its life, if possible, you may treat with colistin or an anti-E. coli alternative. Otherwise, leave and let the bird's immune system grow and fight on its own. These are based off of common causes of diarrhoea. More information is needed for a proper diagnosis and a treatment plan.