When it comes to the health problems of old dogs, kidney disease is second only to cancer. The kidneys remove waste products from the body, so when they begin to deteriorate, toxic waste products build up in the body — often indicated by increased water consumption and urination. Fortunately, a relatively new early renal disease test allows veterinarians to identify kidney disease in the early stages, when it's manageable through diet and sometimes medication. In the past, kidney dysfunction wasn't detectable in blood work until 75 percent of the kidney's function was destroyed, so this test is a big step forward. When kidney disease is caught early, your veterinarian can prescribe a special low-protein diet that won't overwork the kidneys. This change in diet can greatly increase your pug's life span. Remember that a normal, healthy pug doesn't need a low-protein diet. Feeding reduced-protein dog food does nothing for preventing the development of kidney disease.