The Main 16 Causes of Blood in Dog Stool


When we care about our dogs, we want them to be happy and healthy all the time, so we do our best to protect them from any possible disease.

The situation which you may find yourself in if you have a pet dog is seeing blood in your dog’s stool.

We know that this can be frightening and upsetting, as the majority of people would associate blood in stool with cancer, but we are glad to tell you that this does not have to be the case.

Blood in a dog’s stool can be caused by numerous factors, which are not at all that dramatic, and we always suggest that if this is the case, your dog should be investigated by a veterinarian.

Understanding Bloody Stools in Dogs

Blood in stool is medically known as hematochezia or melena.

Which of these two titles will be given depends on whether the blood comes from the dog’s lower or upper digestive system, and it is significant to determine where the problem is with your dog.

There are differences between the two diagnoses and here are some symptoms that can help you tell them apart.

In the case of hematochezia, the blood in the dog’s stool is bright red.

This means that the blood is still fresh and it is probably deriving from the lower intestines, such as the colon or the rectum.

Blood can be either mixed in the dog’s stools, or a few droplets of blood can be seen.

In melena, feces appear tarry and asphalt black, which is caused by the blood that has been digested, thus suggesting that it is coming from the upper intestinal tract.

When we compare these two problems, melena is the one that causes more worries.

This is due to the fact that dog owners sometimes do not recognize Melena, because some dogs may often have dark stools.

Check Your Dog’s Stool for Abnormal Signs

So as to be able to tell whether your dog’s dark stools contain blood, you should follow the advice:

According to Michael D. Willard who is a board-certified veterinarian specializing in internal medicine, dog owners who believe that there is a problem with his/her dog should place the feces on absorbent white paper, check whether there are abnormal signs in the dog’s stool, and record your observations.

In case a reddish tint diffuses from the feces, your dog is probably having melena.

On the other hand, if you find blood, there are numerous factors that can cause this problem, starting from minor issues, such as dietary changes, to more severe cases, such as cancer.

Dog Hematochezia vs. Melena

Hematochezia Melena
Bright red blood in the stool Tarry black stool
Fresh blood Digested blood
Derives from colon or rectum Derives from the esophagus, stomach, or upper small intestine

6 Causes of Fresh, Bright-Red Blood in a Dog’s Stool

We have already mentioned that hematochezia is fresh, bright red blood that can be either found in or mixed with, your dog’s stool.

If we compare it to humans, it is worth noting that fresh blood in dogs does not mean hemorrhoids.

In the case of dogs, red blood in stool comes from the dog’s rectum or colon, so it should be investigated promptly by a vet.

These are a few causes of hematochezia in dogs:

  1. Parvovirus

    Parvovirus is actually a very serious virus that can be often found in puppies.

    It is most frequently detected in black-and-tan breeds, such as rottweilers, German shepherds, and Dobermans.

    Those who have parvovirus will face certain symptoms such as vomiting, diarrhea, lethargy, loss of appetite, and blood in stools.

    If you notice any of these, you must take your puppy to a vet, as this disease can be deadly.

  2. Parasites

    This is the most frequent reason for blood in the dog’s stool, and some of the parasites that can cause it are whipworms, and roundworms.

    You can notice when your dog has these parasites, as there will be blood appearing in your pet’s feces as well as other symptoms showing that your dog has worms.

    A veterinarian will prescribe specific dewormers.

  3. Dietary Indiscretions

    Another reason for blood in a dog’s stool is overeating or dietary indiscretion.

    These situations can irritate a dog’s colon, thus causing diarrhea and bloody stools.

    That is why it is important that if you change the dog’s diet, you should do it gradually over the course of several days, not at once.

    A sudden changing of food can cause vomiting and diarrhea may take place.

    In case you give your dog a new treat or feed him people food, an inflamed colon can be a result.

    There are also other dietary causes of blood in the stool including eating spoiled foods and food intolerances or allergies.

  4. Hemorrhagic Gastroenteritis

    Hemorrhagic gastroenteritis is not only followed by bloody diarrhea but also vomiting.

    So as to help your dog in this situation, you need to take it to a vet, as it may need intravenous fluids and proper medications.

    In the case of Hemorrhagic Gastroenteritis, dogs feel very sick and can get dehydrated, so a quick reaction is important.

  5. Rectal Injuries

    This kind of problem happens when a dog ingests a stick, bone, or another sharp object, which cuts the lower intestinal lining or rectum.

    In certain cases, the object can be seen in the feces itself if it has found its way through your dog’s system.

    This is an ideal situation, being that the blood will be bright red and will stop.

    So as to avoid these bad situations, you should not give your pet sticks or cooked bones to play with.

    The best way to help your dog in these situations is to feed him some high-fiber bread or rice so as to pass the bone.

    Furthermore, it is significant that you check for any rectal injuries, especially any involving the anal glands, due to the fact that if the dog’s stools are well-formed and have fresh blood on the surface, it can suggest a rectal polyp, which is an abnormal growth.

    When the stools pass over the polyp, it bleeds.

    Seeing a vet is important in this case, as the polyp can be felt during a rectal examination, as in some cases the polyp may protrude from the anus.

  6. Stress

    Stress is another reason for blood in the stool.

    What can make your dog feel stressed are certain life events, involving the addition of a new dog or family member to the household, and being boarded in a kennel, as well as moving house.

    All these events are causes of colitis with bloody diarrhea with mucus.

Causes for Melena, Dark Tar-Like Stools in Dogs

6 Causes of Black, Tarry Blood in a Dog’s Stool

We have already described melena, as digested blood in the dog’s stools.

The stool appears to be black and tarry, and many people describe it as “coffee grounds.”

This kind of blood can be from the dog’s lungs, pharynx, esophagus, stomach, or upper small intestine.

It is important to take your dog to a vet in the case of melena, as it is usually caused by serious conditions.

  1. Use of NSAIDS

    There are cases when a dog is on aspirin or some type of Non-Steroidal Anti-Inflammatory drug.

    The usage of these drugs may develop ulcers, which may bleed and cause digested blood coming from the stomach.

    It is significant to keep a watchful eye on a dog’s stools and visit your vet once you notice something unusual.

  2. Blood Clotting Disorders

    Several canine conditions can also cause blood clotting disorders and bleeding.

    The symptom that you can notice is black tarry stools, which indicates bleeding underneath the surface.

    In the case of rat poison, dark tarry stools can be manifested.

    A dog that may have eaten rat poison must see the vet as soon as possible.

  3. Post-Surgery Complication

    A possible situation after surgery can be a black stool, and it is suggested that you take your dog to a vet immediately.

    This may be a symptom of internal bleeding and it usually appears 72 hours after the surgery.

  4. Tumors/Cancers

    Whenever a dog presents dark, blackish stools, you must take it to a vet immediately so as to rule out the possibility of bleeding tumors.

    These unfortunate situations can be quite common in elderly dogs.

  5. Pepto-Bismol

    Some people need to give Pepto-Bismol to a dog, and this medication can turn stools black, which is indicated as a potential side effect.

    However, after you stop giving this medication, the stools must turn back to normal.

    You must know that Pepto-Bismol can cause gastric bleeding and you can give it to your dog only if recommended by a veterinarian.

  6. Ingestion of Blood

    Ingesting blood can also make a dog’s stool black and tarry.

    This is the case when a dog licks a bloody wound or has a mouth injury or nose bleed which causes it to swallow blood.

More Causes

You could find out a lot about many causes of blood in the stool, but those listed are not the only possibilities.

Some of the following can also be reasons for blood in the dog’s stool:

  1. Intestinal blockages
  2. Fissures
  3. Trauma
  4. Bacterial infections, such as those caused by campylobacter or clostridium perfringens

Slippery Elm Bark Remedy for Dog Diarrhea and Bloody Stool

One of the useful remedies in cases of diarrhea that causes hematochezia is slippery elm bark.

There were people who had a dog who came for boarding and unfortunately got stress colitis with bloody stools, so they used GastroElm Plus during his stay.

It is made with 80% slippery elm bark powder.

Its main usage is for pancreatitis in dogs, ulcers in horses, and vomiting, diarrhea, and other gastrointestinal problems in cats, dogs, or horses.

What to Do If Your Dog Has Blood in His Stool

The first thing you must do is see your vet.

In case your dog is pooping blood, plus has pale gums, becomes lethargic, vomits, or has diarrhea, you need to see the emergency vet.

Also, you need to bring along a fecal sample.

This is necessary as the vet can immediately investigate it.

The stool sample should not be more than 12 hours old for accuracy purposes.

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