The body's elimination of waste, whether via defecation or urination is something we take for granted-it is also a physiologic necessity! Have you ever stopped to think about why this physiologic act is so necessary? Is there more to urination than to just maintain our hydration and fluid balance? Urine is one of the ways that the body rids itself of toxins. The kidneys filter the blood, not only to conserve water, but also to remove potentially harmful toxins. Kidneys can become damaged for a myriad of reasons such as infections, environmental poisons and advancing age. In fact, the number one killer of older cats is cancer, with kidney failure coming in a close second.