Because pet rats generally live about two and a half to three years, although there are instances of some of them living longer. But when we talk about an average life span, you'll often find that once your rat is reaching an older, or what we call a geriatric age, they may be in need of special care, or they may have developed certain health problems that require special attention.
A fairly common medical problem of older rats is the development of pituitary tumors, or a tumor that grows in the pituitary gland at the base of the brain that results in leg weakness, that results in hind leg paralysis, where the back legs stop working. Or where they're not able to hold food with their front legs. These rats then, may sometimes start dragging themselves and their quality of life may still be good to the point that an owner feels like it's not necessarily the time that they have to let this pet go, but they may need special care.
Older rats may develop arthritis. They may develop degeneration of the joints. They may develop an age related type of muscle wasting that occurs. They may not climb as well. So, special considerations are going to be extra bedding, an extra cage litter and cage lining. Sometimes taking out levels so that they're not having to climb up ladders or climb up ramps, providing food bowls that are easy to access, lower edges, putting food and water down low in the cage. And having that rat live in a one level type of cage may be the best way to work with them.
So, caring for an older rat, depending on if they develop any geriatric type symptoms, such as leg weakness. Some older rats may develop cataracts and it may affect their vision. And in those cases, if they lose their vision, they may need special accommodations as well as setting up their cage, being sure food and water are readily available. And that they have the means to safely, still continue to live in their environment, but with certain modifications to deal with, what may be a geriatric related conditions.