As food and other material passes through the digestive tract, nutrients and water get absorbed, leaving behind the stool or feces. The animal gets rid of the "leftovers" or "unusable" when it defecates—so the feces are actually a significant clue as to what is going on in your pet’s gastrointestinal tract.

It is important to know the difference between normal, healthy feces, in all of its colorful varieties, and feces that may be indicating a potential medical problem. Unfortunately, many owners do not pay close attention to what their dogs leave behind. This can be a mistake; excrement provides important diagnostic clues that you don’t want to miss. Rather than trying to respect your pet’s "private moments," you should monitor them vigilantly!

To begin with, you need to be well acquainted with what a normal stool sample looks like. Know how much is usually produced and be aware of its color—which can be brown, green, gray, mustard-yellow, and other shades, depending upon the dyes used in your pet’s brand of dog food. When the hue, quantity, texture, or odor changes, chances are that your pet is having a problem.

A warning sign of a potential illness is the presence of bright red blood, or black and tarry feces—this may indicate gastrointestinal bleeding. Mucus, which occurs due to large bowel irritation, gives the stool a very shiny appearance.

A number of disorders can cause your dog’s stool to change, but diet is quite often the culprit. If you feed your dog a fairly consistent diet everyday, you should expect him to have a standard quantity and quality of feces on a regular basis. Be wary of changing your pet’s menu abruptly; the digestive tract of the dog is sensitive enough that a change in the brand of food can cause loose stools for several days to a week.

Diarrhea, often accompanied by weight loss, can be caused by cancer, parasitism, dietary indiscretion or intolerance, and metabolic disorders such as chronic renal failure or hyperthyroidism. Other causes include maldigestion, malabsorption, infectious agents such as viruses and bacteria, mechanical narrowing, inflammatory diseases, drugs or toxins, and pancreatic insufficiency.

Sometimes, you may find lost treasures in your pet’s waste products. If your dog eats a foreign body that is small enough to pass, you should expect to see it in the stool one to three days later. Over the years, I have seen a gold crown, a diamond ring, and numerous children’s toys pass through successfully. The gold crown was sterilized by the owner’s dentist and replaced into his mouth.

If you notice anything unusual about your pet’s feces, your veterinarian can perform a number of diagnostic tests on a stool sample. A fecal floatation is a microscopic evaluation for parasites such as roundworm, hookworms, and whipworms, and coccidia, and fresh fecal smears are done to check for protozoal parasites such as coccidia and giardia.

In addition, screening for the infectious organism Salmonella can be done by performing a fecal culture. The presence of very small quantities of blood due to a bleeding ulcer or intestinal cancer can be detected using a fecal occult blood test. When the dog is actively shedding the virus, a parvo viral infection can be diagnosed using a viral test kit and rectal swab of fresh feces. Other tests include those for the presence of excessive fecal fat and detection of malabsorption.

Plain abdominal x-rays, barium dye studies, endoscopy and colonoscopy are other diagnostic tools that may be used to evaluate disorders of the gastrointestinal tract. Some of these may require referral to a veterinary internal medicine specialist.

In most cases, it is much more likely that a disease can be treated if it is detected early on. Safeguard your pet’s health by taking a good, close look at its stool for signs of possible illness. A pile of waste may not make for the most pleasant scenery, but it can contain crucial information about your canine companion’s wellbeing.