The term melena is used to describe a black, tarry appearing feces, which occurs due to the presence of digested blood in the intestines, or to internal bleeding that has passed into the intestine.
Melena is typically seen due to bleeding in the upper portion of the gastrointestinal tract. It has also been seen in dogs after they have ingested a sufficient amount of blood from the oral cavity or respiratory tract. It is not a disease in itself but a symptom of some other underlying disease. The dark color of the blood is due to the oxidation of iron in the hemoglobin (the oxygen carrying pigment of red blood cells) as it passes through the small intestine and colon.
The symptoms relate to the underlying cause and location of bleeding.
You will need to give a thorough history of your dog's health, onset of symptoms, and possible incidents that might have led to this condition. The history you provide may give your veterinarian clues as to where the blood is originating from. After taking a complete history, your pet’s veterinarian will conduct a complete physical examination. Standard laboratory tests include a complete blood count (CBC), biochemistry profile, and urinalysis. The results of these tests will depend upon the underlying cause of the problem.
Blood testing may reveal anemia with smaller (microcytic) and paler than normal (hypochromic) red blood cells. In cases with chronic blood loss the anemia is usually nonregenerative, meaning the bone marrow does not respond in a normal way to the body's increased demand for red blood cells. In acute cases the anemia is mostly regenerative, as the bone marrow responds normally to the body's increased demands by supplying new red blood cells.
Other abnormalities may include a decreased number of platelets (the cells responsible for blood clotting), an increased number of a type of white blood cells called neutrophils (neutrophilia), and a decrease in the number of both red blood cells and white blood cells. A biochemistry profile may reveal changes related to a diseased state other than intestinal causes of melena, including those of the kidney and liver. The urinalysis may reveal blood in the urine, which is commonly seen in patients with blood clotting defects.
Abdominal x-rays will be taken to look for any masses, foreign bodies that may have been swallowed, and abnormalities in the size and shape of the kidneys and/or liver. Thoracic (chest) x-rays will help in identifying lesions of the lungs and esophagus, also a relatively common underlying cause for melena.
Ultrasounds are also used for internal imaging, and will often return more detailed images of the abdominal cavity and gastrointestinal tract. Ultrasound may reveal masses, liver disease, inflammation of the pancreas, or kidney disease. Another diagnostic tool that your veterinarian is likely to use is an endoscope, a flexible tube that is threaded down into the stomach through the esophagus for direct visualization of masses and/or ulcers in the esophagus, stomach, and/or intestines. Endoscopy also helps in taking biopsy samples for tissue analysis and removing the foreign body, if there is one present.
The term for a very small cell
The term for black feces that has blood in it
Hemorrhage into the back of the eye
A chemical change that has to do with adding oxygen or something like it
A gland that aids in both digestive and insulin functions
An in-depth examination of the properties of urine; used to determine the presence or absence of illness
The prediction of a disease’s outcome in advance
The protein that moves oxygen in the blood
The digestive tract containing the stomach and intestine
A condition of the blood in which normal red blood cell counts or hemoglobin are lacking.
Term used to imply that a situation or condition is more severe than usual; also used to refer to a disease having run a short course or come on suddenly.
Term used to refer to any drug that is used to slow down or stop the clotting of blood for medical purposes.
The process of removing tissue to examine it, usually for medical reasons.
The tube that extends from the mouth to the stomach
A type of instrument that is used to look inside the body
The space in the abdomen that holds the major digestive organs in an animal. Normally referred to as the area between the diaphragm and the pelvis. Also referred to as the peritoneal cavity.