Tarry Feces due to Presence of Blood in Dogs

Blood in your dog’s stool is an important sign that something may be wrong with his digestive system. While a red stool can occur occasionally, dark and tarry stools are a sign of something possibly more serious. The dark and tarry look means that the blood has been digested and has made its way into the upper (small) intestine. The black color of melena is caused by iron in the blood becoming oxygenated when it passes through the ileum and colon. There are many reasons for the presence of melena, but they are all cause for concern so a visit to your veterinarian is essential to your dog’s health. Some of the reasons for melena are listed below.

Tarry feces due to the presence of blood (melena) makes your dog’s stools look black and tarry. There is a difference between fresh blood in your dog’s stool (hematochezia) and melena because the latter can be a sign of a serious or fatal disorder that will need medical attention right away. Melena appears black (from the upper intestine because it is digested) and hematochezia will appear bright or dark red (from the lower intestine or anus because it has not been digested).  The blood can be coming from your dog's lungs, pharynx, esophagus, stomach, or upper (small) intestine and this can mean a serious disorder. It is vital that you take your dog to the veterinarian or an emergency animal clinic or hospital as soon as possible.

The main sign of melena is dark black feces that look similar to tar or coffee grounds. Since there are many different causes for melena, the signs will vary according to the underlying illness or disease. Here are some common signs:

• Black feces that looks like tar
• Diarrhea
• Throwing up (possibly vomiting blood)
• Pale mucous membranes
• Bruises on the body
• Not eating
• Drinking excessively
• Frequent urination
• Loss of weight

There are several reasons for melena in your dog’s feces and it takes a visit to the veterinarian to determine the cause. Some of the possible causes are:

• Infection
• Some medications (such as NSAIDS)
• Cancer
• Swallowing foreign object
• Blood ingestion
• Heavy metal toxicity
• Bleeding disorders
• Metabolic disease
• Hemorrhagic disease
• Gastrointestinal ischemia (lack of blood supply)

Your veterinarian will need to do a complete and thorough physical examination, which includes your dog’s body temperature to see if there is a fever. Important diagnostic information will include blood pressure and heart rate. You will need to provide the veterinarian with as much of your dog’s medical history as possible, including recent illnesses or injuries. Changes in dietary habits, behavior, and activity levels are also important to determine what is causing the melena. Since there are so many different possible causes, your veterinarian will likely recommend further testing, such as:

• Complete blood count (CBC)
• Biochemical profile
• Urinalysis
• Fecal examination
• Abdominal and chest radiographs (X-rays)
• Serology for certain infectious diseases
• Coagulation profile
• Abdominal ultrasonography
• Upper gastrointestinal barium series
• Endoscopy

The treatment will depend on what is causing the melena in your dog’s stool. If the signs are severe or the veterinarian cannot determine the cause, your dog will probably be hospitalized for IV fluid therapy, rest, and 24-hour observation. A blood transfusion will be administered if there is significant blood loss and they will give your dog medication to treat the infection or bacteria that is causing the melena if the veterinarian can determine the cause.

When your veterinarian finds the source of the melena and is able to treat the problem, you may be able to take your dog home sooner, but you will have to make sure your dog gets the rest needed to heal. If the veterinarian prescribes medication be sure to give it as prescribed and finish all the medicine even if your dog seems fine before it is gone. Sometimes the illness will come back if you stop the medication too soon and it will be more resistant to the medication your dog was originally taking.

If the veterinarian says it is okay, your dog can go back to eating his regular food, but go back to it gradually so it is easier on the stomach and digestive system. Do not give your dog any kind of people food no matter how healthy you think it is. Just because it is good for humans does not make it healthy for dogs. Be sure to follow up with the veterinarian and continue to visit regularly on a yearly basis.