Kidney disease is one of the most common problems in old dogs, second only to cancer. As the kidneys age, they become less efficient at removing waste products from the body, causing waste to build up instead of being eliminated with urine. Clearly, it's not good to have toxins remaining in the body, but until recently it wasn't possible to identify the problem until 75 percent of the kidney's function was destroyed. Today, however, a new screening test allows veterinarians to identify kidney disease in the early stages, when it's still possible to manage it with a special low-protein diet that won't overwork the kidneys. Your dog can live significantly longer if kidney disease is caught and managed early — another good reason for regular screening exams.