Acetaminophen as a postsurgical analgesic in rats: A practical solution to neophobia

Acetaminophen administration is gaining popularity as a postsurgical analgesic in many rodent labs despite reports that animals may consume suboptimal doses as a result of taste neophobia. The present study evaluated the presence, duration, and extent of acetaminophen neophobia in adult male and female rats (Long Evans) with the intent of developing a protocol for administration of this analgesic in the rodent surgery lab. After a 7-day baseline period in which average water consumption, food consumption, and body weight were established for 32 rats (20 females and 12 males), cherry-flavored acetaminophen was administered (6 mg/ml) in the animals' water bottles for an additional 7 days. Fluid consumption, food consumption, and weight were monitored during this period of drug exposure. Male rats displayed a transient period (1 day) of reduced fluid consumption followed by elevated fluid consumption on subsequent days. Female animals displayed normal to elevated fluid consumption on all days of drug exposure. Both male and female animals, however, decreased their food intake after drug exposure and subsequently lost weight. Recommendations for the oral administration of acetaminophen as a postsurgical analgesic are discussed.