For example, risk of cancer of the uterus increased substantially at higher body mass index; for other cancers, we saw more modest increases in risk, or no effect at all. (sciencedaily.com)
Studies suggest that, depending on the breed, the risk of an intact female rabbit over the age of 4 developing cancer of the uterus can be as high as 80 percent! (smallanimalchanel.com)
All female rabbits that are not used for breeding should be spayed by 2 - 3 years of age, as cancer of the uterus is common in the rabbit. (riverroadpetclinic.com)