[Charlee]

My chook has runny droppings, she eats a mixture of peletts, maize, corn and greens fromt he kitchen and what she finds in the garden. Her vent area is dirty but none of the others have the same problem.

Could she need a change of diet of have something more sinister?

[Ian_P]

Could be a lot of things Charlee, but its unlikely to be the diet. The logic would say that if it was the diet all your birds would be the same.

It could be a bacteria infection, are the droppings a particular colour?
 Or a parasite, perhaps she has worms.

I would tend to isloate her in a sick pen for a week or so if you can. This will do two things. You will be able to control her diet and you will stop whatever it is spreading to the others.