Relationships between animal welfare, health and environment
The definition of Animal Health includes Welfare
The health of an animal encompasses both physical, mental and social well-being and not merely the absence of disease or infirmity.
This includes :
physical fitness,
freedom from infectious and non-infectious diseases,
absence of abnormal behaviour, pain and suffering and
the ability to carry out essential life maintaining tasks.
Health (of a human) is the state of an individual enjoying complete physical, mental and social well-being and not merely the absence of disease or infirmity (WHO).
Definition based on relation between the animal and its environment

Reminder : A good level of animal welfare
Based substantially on an undisturbed, species specific and ethologically adequate life situation (German Animal Protection Act, 1985)
In harmony with itself and the environment (after Hughes, 1976)
The welfare of an individual is its state as regards its attempts to cope with its environment (Broom, 1986, 2000)