# Why Is My Dog's Poop Black and Tar-Like? Black, tar-like poop in dogs usually means digested blood from somewhere in the upper digestive tract, and it is a sign that should be checked by a veterinarian right away. The medical term is melena, and it often points to bleeding in the stomach or the first part of the small intestine. Because a dog can lose a large amount of blood before you notice other problems, black tarry stool is treated as urgent until proven otherwise. This article is educational and is not a substitute for veterinary diagnosis or treatment. ## Quick Answer - Black, sticky, tar-like stool (melena) usually means the dog has swallowed or is bleeding blood that was digested high in the digestive tract. - This is not the same as normal dark brown poop. Melena is black like coffee grounds or road tar, often shiny, soft, and foul smelling. - Melena can come with serious blood loss. One dog with melena had a hematocrit of 18.8%, far below the normal range of 36% to 56% [1]. - Do not wait to see if it improves on its own. Call your veterinarian or an emergency clinic now, especially if your dog is weak, pale, vomiting, or collapsing. - Do not give human medicines such as aspirin, ibuprofen, or other pain relievers. Some of these cause the bleeding in the first place. ## What Black Tarry Stool Looks Like and What Is Normal Normal dog poop is firm, log shaped, and brown. The brown color comes from bile and the normal breakdown of red blood cells and food as it moves through the gut. Color can shift with diet, treats, or a change in food, and a very dark brown stool is often harmless. Melena is different. It looks like black tar or black coffee grounds. It is usually soft or liquid, sticky, and shiny, and it has a strong, foul odor. The black color comes from blood that was digested as it passed through the stomach and upper small intestine. That is why the stool turns black instead of showing bright red streaks. Bright red blood on the surface of stool is called hematochezia. It usually comes from the lower intestine, rectum, or anus, and it looks very different from melena. If you see bright red blood, that is also worth a call to your vet, but it is a different problem. One more thing to rule out. Some foods, treats, and supplements can turn stool black without any bleeding. Examples include certain chew toys, blood-based treats, iron supplements, and some antacids that contain bismuth. If your dog ate something like that and seems completely normal, mention it to your vet. Do not assume that is the cause, because melena and harmless dark stool can look alike. ## Main Causes of Black Tarry Stool in Dogs Melena means blood was digested, so the cause is usually bleeding somewhere in the upper digestive tract. The table below lists the most common categories. | Cause | Typical clues | How urgent | |---|---|---| | Stomach or intestinal ulcer | Vomiting, appetite loss, black stool, sometimes pain when you press the belly | Emergency, same day | | Bleeding tumor or mass in the stomach or gut | Weight loss, vomiting, weakness, anemia on bloodwork | Emergency, same day | | Medication or toxin (aspirin, ibuprofen, steroids, rat poison) | Known exposure, vomiting, bruising, pale gums | Emergency now | | Severe inflammation of the stomach or gut | Vomiting, diarrhea, belly pain, recent diet change | Urgent, same day | | Bleeding disorder or clotting problem | Bruising, nosebleeds, blood in other places | Emergency now | | Swallowed blood from the mouth or nose | Nosebleed, dental disease, coughing up blood | Urgent, same day | | Addison's disease (hypoadrenocorticism) | Weakness, vomiting, diarrhea, collapse, low blood sodium and high potassium | Emergency now | | Severe parasite burden or other gut disease | Diarrhea, weight loss, poor coat | Urgent, same day | ### Bleeding Ulcers and Stomach Masses Ulcers in the stomach or the first part of the small intestine are a common cause of melena. They can bleed slowly or heavily. A bleeding mass in the stomach can do the same thing. In one report, an 11-year-old dog was brought in for lethargy and melena, and testing showed a hematocrit of 18.8%, which is severe anemia [1]. Imaging found a mass in the stomach, and surgery removed an ulcerated growth that was later identified as a gastric hyperplastic polyp [1]. The anemia resolved on its own after the mass was removed [1]. This case shows how a single bleeding lesion can cause serious blood loss. ### Tumors Outside the Stomach Not every source of melena sits in the stomach. A bleeding mass in the gallbladder can also cause melena and vomiting of blood. In one report, a 9-year-old dog had acute melena, hematemesis, and a month of weight loss [2]. Bloodwork showed mild anemia and a mild rise in a liver enzyme, and an early mucocele was suspected on ultrasound [2]. Treatment with stomach-protecting drugs did not help, and the anemia got worse [2]. Endoscopy of the stomach and upper intestine looked normal, so surgery was performed, and a bleeding ulcerated mass was found at the gallbladder neck [2]. The diagnosis was a neuroendocrine carcinoma [2]. After surgery, the melena and vomiting of blood stopped, and the dog was still free of signs 13 months later [2]. This is a rare cause, but it shows why a full workup matters when the obvious tests are normal. ### Addison's Disease and Severe Blood Loss Hypoadrenocorticism, often called Addison's disease, is another cause of gastrointestinal bleeding in dogs. In one case, a 3-year-old dog came in with repeated vomiting, diarrhea, low body temperature, and lethargy [3]. The dog was in shock with abnormal electrolytes and anemia, and the hematocrit had dropped from 49.2% four days earlier to 17.3% [3]. Melena appeared the next day, and the hematocrit later fell to 9%, which required a blood transfusion [3]. An ACTH stimulation test confirmed hypoadrenocorticism [3]. This condition can cause bleeding that is severe enough to need a transfusion, so it belongs on the list of emergencies. ### Infections and Other Uncommon Causes Some infections can lead to melena as part of a wider illness. In one report, a 9-year-old dog was treated for a lung mass and later developed liver disease and fluid in the abdomen [4]. The dog was hospitalized with vomiting, melena, increased thirst, and increased urination, and testing found an unusual mycobacterial infection in the liver [4]. This is a rare situation, but it shows that melena can be one sign of a serious systemic disease. ## Red Flags That Make This an Emergency Call an emergency clinic right away if you see any of these along with black tarry stool. - Pale, white, or gray gums - Weakness, wobbling, or collapse - Fast breathing or a fast heart rate - Vomiting blood or material that looks like coffee grounds - A belly that looks swollen or feels painful - Known or suspected exposure to rat poison, human pain relievers, or other toxins - Bruising on the skin or gums - A large amount of black stool or repeated episodes Anemia from gut bleeding can worsen quickly. In the Addison's case above, the hematocrit fell from 49.2% to 17.3% in four days and later to 9% [3]. You cannot judge blood loss from the outside, so let a veterinarian check your dog. If your dog also has a hard, bloated belly, read [Why Is My Dog's Stomach So Bloated And Hard](/knowledge/veterinary-medicine/clinical-methods/why-is-my-dog-s-stomach-so-bloated-and-hard) while you arrange care. ## Safe Things You Can Do at Home While You Wait There is no home treatment for melena. Your job is to keep your dog safe and get to the clinic. - Call ahead. Tell the clinic you are seeing black tarry stool so they can prepare. - Do not give food, water, or treats unless your vet tells you to. Surgery or certain tests may require an empty stomach. - Do not give any human or leftover pet medicine. Pain relievers such as aspirin and ibuprofen can cause or worsen gut bleeding. - Collect a stool sample in a clean bag or container if you can do it without delay. - Take a photo of the stool and of your dog's gums in good light. - Keep your dog warm and calm, and carry a weak dog instead of making it walk. - If you suspect poisoning, call your veterinarian or a pet poison hotline right away. Have the product container with you. ## What Your Veterinarian Will Check and Test Your vet will start with a full history, including diet, treats, toys, medicines, and any possible toxin exposure. Then they will do a physical exam, checking gum color, hydration, heart rate, belly pain, and whether your dog is stable. Common tests include: - Bloodwork to check red blood cell count, anemia, and organ values. A low hematocrit supports blood loss, as seen in the cases above [1][3]. - A plasma urea to creatinine ratio. This ratio is used as a marker of upper gastrointestinal bleeding in dogs with anemia [5]. - Clotting tests if a bleeding disorder is suspected. - Fecal testing for parasites and other causes of gut disease. If you have seen worms or odd material in stool, see [How To Tell If Dog Has Worms In Poop](/knowledge/veterinary-medicine/parasitic-diseases/how-to-tell-if-dog-has-worms-in-poop). - Imaging such as X-rays or ultrasound to look for masses, ulcers, or fluid. In one case, ultrasound found a stomach mass that was later removed [1]. - Endoscopy to look directly at the stomach and upper intestine. In the gallbladder case, endoscopy was normal even though a bleeding mass was present elsewhere [2]. - An ACTH stimulation test if Addison's disease is possible [3]. - Exploratory surgery in some cases when other tests do not find the source [1][2]. Treatment depends on the cause. It may include fluids, stomach-protecting drugs, a transfusion, or surgery. Your vet will set any medicine dose based on your dog's weight and health. ## Prevention and Monitoring You cannot prevent every cause of melena, but you can lower the risk. - Keep all human medicines, especially pain relievers, out of reach. - Store rat poison, antifreeze, and other toxins in locked cabinets. - Follow your vet's instructions on any prescribed medicine that can irritate the stomach. - Keep up with parasite prevention and routine wellness visits. - Watch your dog's stool color and consistency. A photo log helps your vet spot trends. - If your dog has a chronic condition such as Addison's disease, keep every recheck appointment. If your dog has other digestive or urinary signs, these guides may help you sort out what to report: [Why Does My Dog Eat Poop?](/knowledge/veterinary-medicine/parasitic-diseases/why-does-my-dog-eat-poop) and [Why Is My Dog having bloody urine? Cystitis Bladder Stones and UTI Guide](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-having-bloody-urine-cystitis-bladder-stones-and-uti-guide). ## Limitations and When to Contact a Veterinarian This article cannot tell you what is causing your dog's black stool. Only a veterinarian who examines your dog can do that. Individual cases need a veterinarian, and timing matters. Contact your veterinarian the same day if you see black tarry stool but your dog is alert, eating, and acting close to normal. Go to an emergency clinic now if your dog is weak, collapsing, breathing fast, has pale gums, is vomiting blood, has a painful or swollen belly, or if you suspect poisoning. Schedule a routine visit if you have seen dark stool that you are not sure about, or if your dog has a known condition that can cause gut bleeding. ## Frequently Asked Questions ### Is black tarry poop always an emergency? It is always worth an urgent call, because melena means digested blood and the amount of blood loss is hard to judge from the outside. Some dogs with melena are stable at first and then decline quickly. Treat it as an emergency until a veterinarian says otherwise. ### Can food make my dog's poop look black? Yes, some foods, treats, and supplements can darken stool without any bleeding. Blood-based treats, iron supplements, and certain chew items are common culprits. Because melena looks similar, have your vet confirm the cause instead of assuming it is food. ### How long does it take for black stool to clear after bleeding stops? It varies with the dog and the amount of blood in the gut. Stool can stay dark for a few days after the bleeding stops. Your vet will track your dog's red blood cell count and overall condition to judge recovery. ### Can I give my dog medicine for an upset stomach at home? No. Do not give human medicines or leftover prescriptions unless your veterinarian tells you to. Some common pain relievers can cause stomach ulcers and bleeding, and the wrong medicine can make things worse. ### What if my dog seems fine but the poop is black? A dog can look fine early on and still be losing blood. Call your vet and describe what you saw, including a photo if you have one. They will decide whether your dog needs to be seen right away or can be monitored at home. ## Related Articles - [Why Is My Dog's Stomach So Bloated And Hard](/knowledge/veterinary-medicine/clinical-methods/why-is-my-dog-s-stomach-so-bloated-and-hard) - [Why Does My Dog Eat Poop?](/knowledge/veterinary-medicine/parasitic-diseases/why-does-my-dog-eat-poop) - [Why Is My Dog having bloody urine? Cystitis Bladder Stones and UTI Guide](/knowledge/veterinary-medicine/symptom-guides/why-is-my-dog-having-bloody-urine-cystitis-bladder-stones-and-uti-guide) - [How To Tell If Dog Has Worms In Poop](/knowledge/veterinary-medicine/parasitic-diseases/how-to-tell-if-dog-has-worms-in-poop) - [Why Does My Dog's Breath Smell Like Metal? Causes & Veterinary Solutions](/knowledge/veterinary-medicine/dental-care/why-does-my-dog-s-breath-smell-like-metal) - [Dog Not Pooping but Eating Normally: Causes and Solutions](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-not-pooping-eating-normally) - [Black Stool in Dogs: Causes and What It Means](/knowledge/veterinary-medicine/digestive-and-urinary-care/black-stool-dogs-causes-meaning) - [Dark or Light Brown Dog Poop: What the Color Means](/knowledge/veterinary-medicine/digestive-and-urinary-care/dog-poop-brown-color-meaning) - [Black Stool and Diarrhea in Dogs With Kidney Failure](/knowledge/veterinary-medicine/senior-and-chronic-care/black-stool-dogs-kidney-failure) ## References 1. [Gastric Hyperplastic Polyp Causing Upper Gastrointestinal Hemorrhage and Severe Anemia in a Dog](https://pubmed.ncbi.nlm.nih.gov/36548841/). Veterinary sciences, 2022. 2. [Neuroendocrine carcinoma of the gallbladder as a rare cause for melena and hematemesis in dogs](https://pubmed.ncbi.nlm.nih.gov/37567183/). Tierarztliche Praxis. Ausgabe K, Kleintiere/Heimtiere, 2023. 3. [A case of canine hypoadrenocorticism needing blood transfusion for severe acute anemia due to gastrointestinal hemorrhage](https://pubmed.ncbi.nlm.nih.gov/31748437/). The Journal of veterinary medical science, 2020. 4. [Hepatic Mycobacterium heckeshornense infection in a dog with cavitary lung disease](https://pubmed.ncbi.nlm.nih.gov/39781405/). The Canadian veterinary journal = La revue veterinaire canadienne, 2025. 5. [Plasma urea:creatinine ratio as a biomarker of gastrointestinal bleeding in dogs with anaemia](https://pubmed.ncbi.nlm.nih.gov/37817453/). Veterinary medicine and science, 2023. ## Further Reading - [American Veterinary Medical Association: First Aid Tips for Pet Owners](https://www.avma.org/resources-tools/pet-owners/emergencycare/first-aid-tips-pet-owners) - [Merck Veterinary Manual: Dog Owners](https://www.merckvetmanual.com/dog-owners) - [Cornell Richard P. Riney Canine Health Center: Canine Health Information](https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information)