As with any NSAID, certain individuals do not react well to these drugs and with Rimadyl, there were enough problems reported after its introduction that a few years ago the FDA made
Pfizer, the company who makes it, re-label their product to include an advisory that this drug could cause death.
In certain dogs, the drug causes stumbling, weakness, loss of balance, seizures, vomiting (including vomiting of blood), tarry stools and full paralysis.