A breed is not completely analogous to the equivalent term for domesticated plants, which is a cultivar. An important difference is that plants are commonly propogated by striking or grafting cuttings. There is no corresponding technique for animals. Cloning may change this if it becomes more available.
A breed should also be distinguished from a strain, which is simply the descendants of a single significant individual, and which in domesticated animals is also known as a bloodline. A strain may not remain entirely within a breed, nor is a breed necessarily composed of a single strain.