Animal welfare refers to the well-being of an animal, both psychological and physical. Good animal welfare in the zoo is important for many reasons (besides the obvious ethical reasons). Firstly, the physiological and emotional wellbeing of an animal must be met in order for it to have optimum reproductive fitness, which is instrumental for conservation purposes. Secondly, with good physical and mental health, animals will exhibit their natural behaviour, which will allow us more insight into their habits and extrapolate this information to study their wild counterparts. Also, animals with good health will inevitably garner more visitors to the zoo as opposed to if they were in bad condition, thereby helping to generate revenue which can be used to various purposes, including research and education.

It is imperative that there is more than one measurement of welfare, in order to avoid over-reliance on that single measurement as well as to provide a comprehensive and overall assessment of the animal in question. Here, various methods for measuring animal welfare will be introduced.