When a dog with B-cell lymphoma initially responds to chemotherapy but the cancer later returns, this is termed a relapse. Treatment given at this point is called rescue therapy. Unfortunately, virtually all dogs treated for multicentric lymphoma will eventually relapse, typically after a first remission lasting six to eleven months. At relapse, the cancer cells may have developed some resistance to the drugs used initially, which is why second-line ('rescue') protocols use different agents. Second remissions can usually be achieved, but they tend to be shorter than the first, and each successive remission becomes progressively harder to obtain and briefer in duration. The choice of rescue protocol depends on which drugs were used first line, how long the first remission lasted, and the dog's overall condition. Despite the challenges, many dogs can still enjoy a good quality of life for several additional months with appropriate rescue therapy.