Blood in Dog Stool: Why Is My Dog Pooping Blood?

By: Somyr PerryUpdated:

Blood in Dog Stool: Why Is My Dog Pooping Blood?

It can be alarming to discover that your healthy, happy dog is suddenly pooping blood. There are many issues that could result in your dog pooping blood, and some are more serious than others.

Is Your Dog Pooping Blood?

While it might sound unpleasant to familiarize yourself with what your dog’s poop usually looks like, it’s an important key to recognizing a potential problem.

“Normal dog poop should have a light-brown to dark-brown appearance, formed but not too dried or hard,” says Dr. Karen Delfin Peacock, DVM, veterinarian at Animal Medical Clinic of Salt Lake City. But if you notice red streaks or extra-dark stools, your dog might have blood in its stool.

“You might see fresh blood on the outside of the stool or within diarrhea,” says Dr. Peacock. “The stool can also have a black, tarry appearance or look like coffee grounds if there is melena.”

What Causes Blood in Dog Stool?

Melena is the veterinary term for black, tarry stool, and typically indicates potential bleeding in a dog’s upper GI tract, according to the Merck Veterinary Manual. It differs from dog poop that appears with fresh, bright red blood, called hematochezia, which usually indicates lower GI bleeding.

Dr. Peacock says that the causes of blood in dog stool are numerous, but the most common reasons include:

  • Hemorrhagic gastroenteritis, or inflammation of the lining of the stomach and small and large intestines
  • Peptic ulcers, which are erosions in the GI lining
  • Intestinal polyps, or masses of tissue that arise from the bowel wall
  • Cancer
  • Inflammatory bowel disease
  • Foreign bodies that have been ingested
  • Drugs or toxins
  • Infections

She notes that there are different types of infections that result in a dog pooping blood, such as bacterial, viral (including parvo) or fungal.  And, there are several different types of parasites that can cause blood in dog stool, says Dr. Peacock.

What to Do if Your Dog Has Bloody Diarrhea

While you might want to try and help stop your dog’s bloody stools at home, Dr. Peacock advises against searching for remedies online that could harm your dog even further.

“There is a common remedy seen on the Internet about giving over-the-counter medicines like Pepto-Bismol,” she says. “I do not recommend this! There is a part of that medication that will change to the active chemical that is the same as aspirin. This can cause ulcers, and will also change the stools to appear black, so it will look like melena (even if it’s not).”

In general, avoid giving your dog any medication that is intended for humans.

The best thing you can do at home is to keep your dog well-hydrated, she says, and take these steps to prepare for a visit to the veterinarian:

  1. First, collect a sample of the bloody poop so you can bring it with you to your appointment. A fresh sample is best. Use dog poop bags and seal it for transport.
  2. If you’re not able to collect a sample, take pictures of the poop with your phone to show the veterinarian.
  3. Make a note of your dog’s living space. Look for items that your dog might have chewed or eaten, or human medications or drugs that are missing.
  4. Finally, investigate your yard, garage and even your neighbors’ yards for toxic substances that could potentially cause your dog harm.

How Is the Cause of Blood in Dog Stool Diagnosed?

Your veterinarian will begin with a physical exam to determine any obvious reasons for blood in your dog’s stool, then follow up with a few tests to give them clues and track down the cause of the blood.

“One test is a parasite exam with a stool sample, which is why it is important to bring a sample with you,” says Dr. Peacock.

There are also blood tests that analyze different types of blood cells, look for anemia and signs of infection, and check a dog’s platelets, which aid in clotting blood.

“Sometimes there are metabolic causes, so a chemistry panel will analyze liver and kidney functions, and check proteins and electrolytes,” she says.

More specialized tests might be required to narrow down the cause of your dog’s bloody stool, including an abdominal ultrasound, an endoscopy, a colonoscopy or special assays for specific diseases.

How Is Blood in Dog Stool Treated?

Treatments vary and are highly dependent on the results of your dog’s physical exam and laboratory tests.

They include the following:

  • Oral Medication for Parasites or Infections: Intestinal parasites, such as hookworm, can lead to the presence of blood in poop. Diagnosis and treatment require a fecal (poop) exam by a veterinarian and oral deworming medication. Follow-up poop testing is usually recommended to ensure the parasite has been treated effectively. Infections with bacteria or viruses may require treatment with oral medications. Medications to reduce inflammation in the gut, lower stomach acid, stop vomiting and diarrhea and treat infection may all be required. In some cases, antibiotics are combined with other oral medications, such as antacids, dewormers, probiotics and anti-inflammatory medication. The choice of oral medication used depends on the diagnosis.
  • Fluids: With digestive upset and blood loss through poop, dogs can become dehydrated. Your vet may provide fluids to help. In mild cases, a little bubble of fluid is administered under the skin where it can slowly be absorbed. In cases of moderate to severe dehydration or blood loss, intravenous fluids are typically required. This requires a hospital stay with placement of an intravenous (or “IV”) catheter to administer fluids. Fluids contain both water and electrolytes to support your dog’s needs until the cause for bloody poop has been treated.
  • Probiotics: There are both “good” and “not so good” populations of bacteria in the gut normally. The good bacteria help to break down food and nutrients so they can be absorbed and used to fuel the body. In cases of digestive upset, illness or inflammation, the bad bacteria can start to outnumber the good. Probiotics, which are live beneficial bacteria and/or yeast, may help to restore the balance between good and bad and aid in digestion.
  • Vitamin Injection: Bloody poop in dogs can be seen with diseases that cause inflammation in the gut. Things like inflammatory bowel disease, bowel cancer and pancreatitis are a few examples. If inflammation is significant, it can interfere with normal absorption of vitamins and nutrients from food. This can lead to imbalances throughout the body. Vitamin B12 (or cobalamin) is one example of a vitamin that can become deficient. If your vet suspects or diagnosis cobalamin deficiency, they may suggest vitamin B12 injections or other forms of supplementation.
  • Pain Medications for Cramping: Diseases that cause bloody poop in dogs can be painful, with some leading to bloating or cramping. Choosing an appropriate pain medication can be difficult in these cases because some can have negative effects on the gut. Some opioids, for example, slow down gut movement, which can lead to more discomfort. And some anti-inflammatory medication can lead to ulcers and more inflammation. Your veterinarian will prescribe pain medication specifically based on the need of your dog and the reason for their condition. It’s not safe for you to administer over-the-counter human pain medications to your dog since many are toxic. If you think your dog is in pain, consult a veterinary professional for advice.
  • Steroid: Steroids may be used to manage certain inflammatory conditions affecting the gut, such as IBD (inflammatory bowel disease). Reducing inflammation can allow the gut to heal and settle, making absorption of nutrients more efficient and reducing loss of blood. Steroids should only be administered in cases where a specific diagnosis has been made that is proven to be steroid responsive.
  • Acid Reducers: Acid-reducing medications may be prescribed to manage conditions such as stomach ulcers, acid reflux, chronic vomiting or regurgitation, or with any diseases suspected to cause hyperacidity in the stomach.
  • Chemotherapy: Chemotherapy medications may be prescribed to manage conditions resulting in severe inflammation in the gut. This includes certain cancers of the digestive tract or severe inflammatory bowel disease. Chemotherapy are prescribed based on a specific diagnosis and often in conjunction with a visit to a veterinary specialist.
  • Surgery: Surgery is performed on the gastrointestinal tract for many reasons. Some examples include bowel obstruction (to remove something that was ingested, blocking movement of food through the gut), removal of diseased tissue, sampling for biopsy (to aid in a diagnosis) or to correct the positioning of internal organs (in the case of gastric dilatation volvulus or “bloat,” which is a life-threatening condition).

Frequently Asked Questions

Q: Is black dog poop normal? 

A: Black dog poop generally is not normal. Dog stool can come in a variety of colors, but most of the times it’s a shade of brown. Black stool that appears dark and tarry usually indicates the presence of digested blood. Blood would be digested if it comes from the upper part of the digestive tract passing down through the small intestines. This means the source of the blood could anywhere from the mouth, esophagus, stomach or small intestines. Conditions or issues such as dental disease, stomach ulcers, toxins, certain medications, infections, kidney disease, liver disorders, bleeding disorders, immune conditions or issues in the gastrointestinal tract itself can be a cause. Occasionally black dog poop may be seen with ingestion of certain non-toxic items or medications. For example, eating blueberries can cause poop to have a black appearance. Certain medications, as they are metabolized, may also cause poop to appear black.

Q: What does blood in dog poop look like? 

A: If there’s blood in dog poop it will look one of two ways: 1) If it’s coming from lower down in the digestive tract (for example the colon), it will appear red. The red may be mixed in with brown colored poop, or be a coating on top of or outside of the poop. There may also be droplets of red on the ground nearby the poop. 2) If the blood is coming from the upper part of the digestive tract, there will be a dark and tarry appearance to the poop, making it look black in color. This can also be mixed in with brown colored poop, or the entire thing may appear black.

Q: Can antibiotics cause black stool in dogs?

A: While certain medications can lead to changes in the color of poop, antibiotics specifically do not tend to cause black discoloration of poop, although it can lead to gastrointestinal upset. If the diarrhea and inflammation in the gut is severe, it could lead to blood in the stool. And again, depending on where the blood comes from, may make the poop look red or black. Other drugs can directly affect the color of poop. While not used commonly, things like Pepto-Bismol can cause darker or even black colored poop. (Warning: Never give your dog medications meant for humans unless directed by your veterinarian.)

Q: Can blueberries cause black stool in dogs? 

A: Yes, if large quantities are ingested, or in the case they are swallowed whole, blueberries can cause poop to appear black or to have black spots mixed in with the normal brown color. Blueberries are a healthy treat that should be consumed by dogs in moderation.

Q: Is blood in dog poop serious? 

A: Blood in dog poop can be serious. If your dog is pooping blood, call your vet. Your veterinarian can determine whether the change in your dog’s poop color may be due to something benign (like eating blueberries) or something more serious, such as a poison or underlying medical condition.

Conditions or issues such as dental disease, stomach ulcers, toxins, certain medications, infections, kidney disease, liver disorders, bleeding disorders, immune conditions, or issues in the gastrointestinal tract itself can all lead to blood in poop. Some of these can be quite serious and require supportive care in the hospital. Others can be treated on an outpatient basis with medications and diet changes. Occasionally black dog poop may be seen with ingestion of certain non-toxic items or medications. By asking a series of questions, the veterinary professional can help give you the best advice on whether your dog needs to see a vet.

Your dog's poop can give you helpful insight into your pup's overall health. So if you notice that your dog's poop seems off, your best bet is to give your vet office a call—it's better to be safe!
Expert input provided by Dr. Karen Delfin Peacock, DVM, veterinarian at Animal Medical Clinic of Salt Lake City, and Dr. Christina Fernandez, manager of veterinary services at Chewy.


By: Somyr PerryUpdated: