If you keep your chickens in good conditions and feed them well, then they should reward you by staying healthy. Sometimes they do get sick – and it is very difficult to diagnose what is wrong with poultry. Few vets specialise in them and if you find one that does, you are lucky. Keeping them warm and hoping they recover is about all you can do.
People are often very confused about how much space they need for their chickens. DEFRA regulations defining the marketing terms ‘battery’, ‘barn eggs’ and ‘free range’ are set out here. In my opinion, the ‘free range’ classification should be taken as an absolute minimum.