The most common side effects are related to the digestive tract and kidneys. Prostaglandins are required to protect the lining of the stomach and intestines. As NSAIDs promote fewer prostaglandins or some of their activity are blocked, the entire digestive tract can be more prone to damage. This can lead to ulcers and perforations (holes) in the stomach and intestines. NSAIDs are slightly acidic and when trapped in the stomach, can directly irritate the stomach lining. Giving a dog two NSAIDs at the same time, or an NSAID with a steroid such as prednisone increases the risk of side effects in the digestive tract and should be avoided. Chemicals created through the COX pathway are important for proper kidney function. NSAIDs can reduce blood flow to the kidneys which can lead to kidney damage or failure. NSAIDs should be avoided with dogs that already have a kidney condition.