Rimadyl (Rx) (Carprofen) was recently approved for use in dogs in the United States. It has been available in other countries for some time. It is reported to be much less likely to cause gastrointestinal upset and kidney damage than older non-steroidal anti-inflammatory (NSAID) medications such as aspirin or phenylbutazone. It is reported to be very effective in conversations on the veterinary mailing lists and bulletin boards. With all new medications there is a period of time when everyone is worried that an unforeseen side effect may occur. The U.S. is a huge market compared to other countries and the really rare problems tend to show up faster here than in smaller markets. The presently available data suggests that this is a safer and possibly more effective treatment than other NSAID medications, though. Gastric upset is less common with carprofen than with other non-steroidal anti-inflammatory medications but it still can occur.