The next time you take your dog for a walk, think of it as a mini health screening. You can get an early warning of medical maladies, veterinarians say, by looking at your dog's urine and watching the way he voids. Find an area of white sand (or snow) -- that way you can see the urine.

An abnormal color might indicate a problem. Red urine often means blood and possible infection. Orange urine could signal bilirubin, a component of bile secreted by the liver into the intestinal tract; high levels can lead to jaundice and reveal problems in the liver and bile duct.

If your dog strains to pass urine, he might have some kind of blockage -- perhaps even a tumor. If he frequently voids small amounts of urine or urinates in unusual places, he may have a urinary tract infection. Schedule a vet visit right away.

Even without abnormal color, a complete urinalysis (UA) as part of a dog's regular check up provides information about the health of several organ systems, including the urinary tract. Information from urinalysis can be obtained in a matter of minutes, while blood work results usually take a day or more.

There are many insights to be gained from urinalysis that cannot be gleaned from blood work alone, and when blood and urine test results are obtained simultaneously, each becomes more valuable.

A complete urinalysis should look at specific gravity, color, sediment, turbidity (cloudiness when sediment is stirred), odor, pH, any abnormal amount of protein and possible glucose, bilirubin and blood.

Measuring specific gravity (USG) determines whether urine is concentrated or dilute. Normally, the kidneys maintain hydration by preserving fluid during filtration, resulting in concentrated urine. If the kidneys aren't working well, fluid loss results in more dilute urine. For evaluating kidney function, measuring USG is imperative. Clinical symptoms of kidney disease often don't emerge until 75 percent of the kidney's function is lost. In the early stages, the only sign of kidney disease is that of an abnormally dilute urine in the presence of normal blood analysis. Other systemic diseases such as diabetes insipidus, Cushing's or Addison's disease, can lead to dilute urine when there is no kidney disease.

The dipstick (the "dip"), which is rapid and simple to perform, measures various urine components. Small drops of urine are placed on a plastic strip lined with a series of colored indicator squares. Changes in color reveal acidity or pH, the presence of blood cells, glucose, ketones, bilirubin, protein and other components. Red blood cells could indicate a bladder or kidney infection. The presence of bilirubin points toward liver disease. Elevated protein levels may indicate a kidney disorder.

The urine sediment is examined as the last part of the urinalysis. A small amount of urine is spun to settle out any solid particles. What's left in the bottom of the tube is viewed under a microscope. Normal urine has little or no sediment, but abnormal urine may contain crystals, red blood cells, white blood cells, bacteria, cancer cells, kidney cells and other clues to problems along the urinary tract.

The value of urinalysis is clear, and it is never a waste of money. Even normal urinalysis results yield valuable information about what diseases are not present. Ask your vet about Heska Corp.'s new Early Renal Disease test (www.heska.com).