Are long term painkillers safe for my horse?

are no subtle early signs of problems developing which may necessitate a change in protocol or drug. 
In summary when used in appropriate cases at the correct dosage NSAIDs are very effective
They are frequently used long term in cases such as osteoarthritis or laminitis but they can cause side effects. It is vitally important that your horse is carefully monitored and reassessed before and during administration of these drugs. Your veterinary surgeon will be able to advise on the suitability of these drugs for your horse as well as other drug or treatment regimes that may be helpful in addition to or as an alternative to NSAIDs.