Makowska, I. J., Weary, D. M. 2013. Assessing the emotions of laboratory rats. Applied Animal Behaviour Science 148, 1-12.

Rats are one of the most commonly used species in research, and decades of testing have yielded a large amount of information pertaining to their experience of emotion. The aim of this review is to bring together information on rat emotion from across a number of disciplines and over several decades, making this information easily accessible to those working with rats. Knowledge of rats' ability to experience emotions including pain is important as this helps to inform and motivate concerns for welfare. Rodents are used in greater numbers than other mammals, in more invasive research and are less likely to receive post-operative analgesia; this treatment likely reflects the perception that rats are somehow less able to experience the range of emotions that would result in suffering associated with these procedures. This paper reviews the range of scientific methods used to infer emotional states in animals including rats; evidence resulting from the application of these methods, as well as descriptions of spontaneous behavioural changes, provides evidence that rats likely experience a range of positive and negative emotions. Given these abilities we conclude that current standards of housing and care are likely to profoundly affect their welfare.