It is done in both cage and floor housing systems. Skeletal weakness can be caused by high levels of egg production. Shackling upside down for slaughter will cause further injuries for birds with leg weaknesses. Also, the soles of the feet can be damaged through pressure on the thin wire floor of cages. Hens also suffer from metabolic disorders, impacted eggs, prolapses and disorders of kidneys and liver are common.
Routine vaccination is given to counter most infectious diseases.
However, when problems do occur, it is easy for injured or diseased birds to be overlooked in cage systems. Endoparasites are treated routinely, but there is an increasing problem with mite infections. The environment of a battery cage clearly does not give hens the freedom to express normal behaviour. Restricted space also prevents birds from carrying out 'comfort behaviours,, such as wing flapping, shaking and stretching, and from having necessary 'personal space' and the ability to retreat from aggressors. Perching When conditions permit, hens seek perches to roost upon at night.