Onsior is a palatable tablet in five sizes. The active ingredient is Robenacoxib. This is a NSAID (Non- steroidal anti-inflammatory drug.) It is amongst the most modern of the NSAID’s. It is used in both cats and dogs – note there is a special size tablet for cats and of course different sizes for dogs. It is used for the relief of pain and inflammation especially in musculo-skeletal cases (arthritis, myositis, sprains and strains etc) and is it a very useful drug. Like all NSAID’s it can rarely irritate the stomach and or intestines even to the extent of causing bleeding. Any vomiting or passing of blood should cause you to stop administering Onsior and let us know urgently.