FARESHARE: An open-source apparatus for assessing drinking microstructure in socially housed rats.

Social factors have been shown to play a significant and lasting role in alcohol consumption. Studying the role of social context on alcohol drinking is important to understand the factors that contribute to the initiation or maintenance of casual and problematic alcohol use, as well as those that may be protective. A substantial body of preclinical research has shown that social environment such as housing conditions and social rank plays an important role in alcohol consumption and preference, though the extent of these effects have been obfuscated by methodological differences and technical challenges. Robust individual differences in alcohol intake in socially housed animals are difficult to track when animals share a common fluid source. Commercial solutions are prohibitively expensive and are limited by proprietary software and hardware (including caging systems). Here we describe FARESHARE, an affordable, open-source solution for tracking fluid consumption in socially housed rats. The device uses RFID and custom hardware to individually measure and record each rat's fluid consumption and licking microstructure. Each bout is also timestamped such that the circadian effects of drinking behaviour may be analysed. We provide a validation showing the operation of the device in a two-bottle-choice alcohol-drinking paradigm over a nine-day period in four group-housed female rats. We show that FARESHARE is able to capture traditional measures such as daily intake and preference, as well as circadian effects, microstructure, and individual variations in drinking.