The kidneys have several important functions in the body, including eliminating waste products through the urine and regulating the body’s fluid balance. The urine specific gravity (SG) test tells your veterinarian how concentrated your pet’s urine is (how much water it contains). If the SG is too high, it can mean inadequate amounts of water are being eliminated through the urine. If the SG is too low, it can mean the body is losing too much water through the urine. There is a relatively wide range of normal readings for a urine SG test, but there are also several medical conditions that can affect the result.