No one wants to admit it, but we all monitor our stool on a daily basis. A change in the stool can be a significant finding and this also is true in our pets.

While some changes can be due to diet — for instance, beets can make your stool red and corn can come through whole — a couple of changes can be the first indicator of a more serious underlying problem.

Melena is the name used to describe dark, tarry stools that are the result of digested blood. The duration of time that the blood is in the GI tract determines the color and, as such, we tend to see this color of stool when there is bleeding higher up. The bleeding can originate from the nose and be swallowed, back of the throat, esophagus, stomach or small intestine.

Possible causes include neoplasia (benign and malignant growths), ulcers, severe inflammation, parasites, torsion, liver failure, bleeding disorders and foreign bodies.

An interesting fact is that many normal animals that eat meat-based diets can have black feces and there are some medications that can cause the stool to be dark as well.

Hematochezia is defined as the presence of red blood in the stool. This is typically seen with large bowel disease, specifically colitis.

It also can be seen with bleeding lesions around the rectum. These patients tend to have other signs consistent with disease in the large intestine, including straining to defecate, increased frequency to defecate and mucous in the stool.

Acholic stools are grey to chalky white and are seen when bile pigment is not present. This type of stool can be an indicator of a malabsorption issue.

Another change that can be seen in cases with malabsorption is solid food particles noted in the stool. Exocrine pancreatic insufficiency is a progressive loss of pancreatic cells that results in failure of the digestive enzymes to be produced. This is most commonly seen in younger dogs (German Shepherds) and typical signs include weight loss despite an increased or ravenous appetite.

The first step with any of these is to get a good history followed by a physical and rectal exam. The history is key as many older pets are on medications (NSAIDs or steroids) for arthritis or another condition that can cause intestinal tract ulceration.

In a younger pet, dietary indiscretion (eating something they shouldn’t) is higher on the list to rule out.

Toxicity from ingesting rat bait causes abnormal bleeding and is still relatively common, especially in younger dogs.

A rectal exam allows me to look at the feces myself and can identify masses or lesions within the colon. Blood work, urine and a fecal sample are the basic samples needed to start the evaluation. The blood work helps us determine if there is a problem with platelets or organ function resulting in the changes in the stool as well as the severity of the blood loss if present. The fecal sample helps identify parasites.

The combination of history, age and breed of your pet, clinical signs, physical exam findings as well as basic blood and fecal results helps determine the next diagnostic test.

Imaging of the chest and abdomen with X-rays and ultrasound is routinely recommended in younger pets that could have ingested a foreign body and in older pets when we are concerned about the possibility of cancer. Pain in the abdomen also would make imaging of the abdomen a priority.

Additional testing that might be recommended includes specific blood work to assess clotting times if ingestion of rat bait is a possibility, and testing for pancreatic insufficiency and/or vitamin deficiencies. Depending on what is found, treatment can vary from medical management to endoscopy/colonoscopy and even surgery.

Endoscopy/colonoscopy is performed under general anesthesia. A flexible camera is passed down the mouth, through the esophagus, into the stomach and small intestine in an upper GI endoscopy, and up the large intestine in a colonoscopy. These minimally invasive procedures allow us to visualize lesions and to obtain biopsies if needed.

Surgery is recommended when organs other than the intestinal tract are thought to be the cause, when we think surgery will be curative, or when we do not think we can reach the lesion with the flexible scopes. In the majority of cases, we are able to determine the source of blood loss and institute specific treatment to resolve the issue. In cases with severe blood loss, a blood transfusion can be required before the bleeding has resolved.

Monitoring your pet’s stool daily for changes might not be the most pleasant thought, but it certainly can be an indicator as to their health. And in some cases, it can help us identify a problem before it becomes life-threatening.

Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to