Regarding the Inadvisability of Administering Postoperative Analgesics in the Drinking Water of Rats (Rattus norvegicus)

The feasibility of administering the pain reliever acetaminophen to rats via their water bottles was examined in this study. Two different preparations of acetaminophen were used, a cherry-flavored suspension and an alcohol-containing solution. Both preparations of acetaminophen were diluted to 6 mg/ml by using normal drinking water. When healthy unmanipulated rats were exposed to either of the acetaminophen preparations for the first time, the animals showed a dramatic reduction in fluid intake. A marked reduction in food intake also was associated with the cherry-flavored preparation. These reductions appear to be an expression of the well-characterized neophobic response that can be demonstrated by rodents when they encounter a novel taste. This neophobic behavior suggests that administering pain relievers to rats via their drinking water is counterproductive as a means of providing pain relief.