Kidneys are vital organs that have been tasked to take waste out of our, and our fur kids, blood, balancing body fluids, and making pee. Kidneys act as the body’s waste filtration system. They have the same function as your human kidneys. Kidney (renal) disease occurs when kidneys are damaged and cannot filter blood correctly. Over time, the “waste” build-up in the body, which can cause additional health problems, and eventually lead to kidney failure. In mutts, pups, nobles and masters, the kidneys use about 20 percent of their heart’s blood to operate. Unlike the liver, kidneys cannot rejuvenate.