Chronic pain is a big problem that often occurs in dogs, and it also causes a lot of stress to the owners who take care of them. Sometimes it is very difficult to recognize chronic pain in dogs because the changes in their behavior are so subtle that only the owner can see them. One of the most common causes of this pain is osteoarthritis. Osteoarthritis is the most common chronic disease of the locomotor system. It is a degenerative, progressive, inflammatory and painful process that affects the entire joint. It is treated in various ways: weight loss, exercise and medication. The most commonly used drugs are non-steroidal anti-inflammatory drugs, but as their use can have many side effects and cannot be used for a long time (and osteoarthritis therapy is usually lifelong), new drugs are always being sought to help with treatment. Grapiprant is a new drug used for this purpose. Its advantage is that it acts much more specifically on receptors, unlike other non-steroidal anti-inflammatory drugs. It has proven to be a good drug in the treatment of mild to moderate osteoarthritis with mild side effects. It has proven to be able to be used for a longer period of time and has also been shown to be a good choice in dogs homozygous for the MDR1-1Δ gene with a dose reduction. For this reason, it should be used regularly in the treatment of osteoarthritis in dogs.