Top 8 Causes of Bloody Diarrhea in Dogs and Available Treatments


– Diarrhea is common in dogs, but when you see blood in it, it's best to immediately consult a veterinarian.

– There are different causes for bloody diarrhea in dogs, including Parvovirus, parasites, Hemorrhagic Gastroenteritis, changes in diet, Inflammatory Bowel Disease, and rectal injuries, among others.

– Take note of the bloody diarrhea's features such as appearance, color, and smell. You can also take a picture or better, take a stool sample to your vet.

– A healthy diet, regular exercise, timely vaccination and deworming among others should keep your dog's gut healthy and prevent bloody diarrhea.

Bloody diarrhea in dogs can be scary, knowing that this could be the symptom of a life-threatening condition.

But don't worry; it won't last long as long you work with your veterinarian.

I've handled many doggy diarrhea cases myself with pet owners who were either prompt to act or hesitant to have their pups over at the clinic.

But let me tell you: a dog's bloody diarrhea must be addressed by a veterinarian immediately.

In this article, let me share with you the common causes of bloody diarrhea in dogs, as well as treatment options, prevention, and what you, as the pet owner, should do immediately.

Jump to each section:

Bloody Diarrhea in Dogs Symptoms and Causes Infographics

Bloody Diarrhea in Dogs: What Does it Look Like?

Bloody diarrhea is a soft, runny stool that can have varying amounts of blood within it.

While it's easy to imagine what it looks like, you might observe it in different forms.

Sometimes, it could be just streaks; other times, it could be full-blown red blood and loose stool.

Some key signs to look for include:

  • Dark, tarry stool: The blood may cause diarrhea to appear very dark, almost black in color. This indicates older blood.
  • Bright red blood: Fresh blood will appear as vibrant red streaks or liquid mixed into the diarrhea.
  • Wet, liquid stool with blood: Bloody diarrhea is usually loose and watery in consistency due to blood mixing with the gastrointestinal contents.
  • Blood clots: Larger clots or globs of blood may occasionally be seen mixed in with the diarrhea.
  • Black, sticky stool: Occasionally, blood degradation products will cause very black and tarry stool resembling motor oil.
  • Blood on the fur around the anus: Bleeding may cause bloody staining on the skin, fur, or floor near where defecation occurred.

The 2 Types of Dog Bloody Diarrhea

There are two types of bloody stools in dogs, and, given the appearances we have described above, they can be easily distinguished.

Hematochezia has the appearance of bright red and fresh blood in the dog's feces. This blood comes from the lower part of the digestive tract, and there are numerous potential causes.

Melena has a black and tarry blood look with sticky feces, which occurs when the dog swallows or digests blood. It is usually the result of bleeding in the upper digestive tract and also has many possible causes.

Any amount of visible blood in the stool should be evaluated by a veterinarian as it can indicate underlying health issues and cause for concern.

If the diarrhea is severe or is caused by a fatal condition like Hemorrhagic Gastroenteritis (which we'll discuss later), then it could be life-threatening.

ALSO READ: The Best Dog Food for Dogs With Diarrhea and Loose Stools

Bloody Diarrhea in dogs

8 Common Causes of Bloody Diarrhea in Dogs & their Treatments

There are numerous reasons for bloody diarrhea in dogs.

Some are harmless, but others can be life-threatening.

Your job as an owner is to read the signs, recognize changes in your dog’s behavior, and seek veterinary treatment as soon as you suspect that something is wrong.

1. Parvovirus

Canine Parvovirus is a highly contagious viral infection that usually attacks the intestinal tract, but other forms of this disease can attack the heart muscle itself.

The most obvious signs of a dog suffering from parvovirus are:

  • Vomiting
  • Severe bloody diarrhea in dogs
  • Extreme weight loss
  • Lethargy
  • Fever
  • Hypothermia
  • Noticeably red mouth and eyes

As this disease is highly infectious, your dog can pick it up either through direct contact with another infected animal.

They may sniff an infected canine's excrement, or you may have accidentally stepped on one and brought it home with your shoes.

Treatments for Parvovirus in canines include:

  • IV Fluids
  • Antibiotics
  • Injectable vitamins
  • Colostrum in puppies

Parvovirus is deadly to dogs if left untreated.

Without any type of treatment, most infected dogs will die from the [parvovirus] disease. And even with aggressive therapy, some dogs won't make it. It can be very costly to treat them. Your best bet is prevention and keeping up with the vaccine series.

Susan Nelson, DVM, clinical associate professor at Kansas State University

2. Hookworms

Especially dangerous to young puppies and older dogs with weakened immune systems, these parasites clamp onto the wall of the small intestine and suck blood from their host.

MADR hookworms present an even greater need for veterinarians to counsel owners on parasite control, fecal hygiene measures, and required routine diagnostics

-Dr. Pablo Jimenez Castro, AAVP

Symptoms of hookworms include:

  • Anemia
  • Pale gums
  • Lethargy
  • An unhealthy coat and flaky skin
  • Coughing

The hookworm is usually passed on from mother to pup through her milk.

Another way that a dog can contract hookworms is through direct skin penetration from the larvae.

Treatments include a parasitic dewormer for dogs and iron supplements.

However, experts have found hookworms that are drug-resistant, so the American Association of Veterinary Parasitologists made a task force for it in 2021.

The AAVP Task Force encourages state veterinarians to share information about drug-resistant hookworms because of the potential widespread transmission and zoonotic risk.

3. Hemorrhagic Gastroenteritis (HGE)

This condition baffles veterinarians as little is known about what causes it.

The cause of HGE is still unclear so there is no way to prevent the condition. Small, young, purebred dogs are more prone to HGE but it can affect any size or breed.

– Dr. Katja Lang, Heart of Chelsea Animal Hospital, New York

Known to attack young small breed dogs predominantly, this condition is caused by the body reacting adversely to food or bacteria.

This reaction causes proteins, red blood cells, and fluids to leak through the lining of the intestinal tract.

Perhaps most confusing is the fact that this takes place even when no inflammation is present.

If your dog suffers from Hemorrhagic Gastroenteritis, catching it quickly will help a lot, according to case studies from other vets and research.

Keep an eye out for the following symptoms:

  • Sudden vomiting
  • Bloody diarrhea in dogs with a foul odor
  • Depression
  • Lethargy
  • Weight loss

Most prevalent in young small breed dogs are highly strung and stressed canines.

The unfortunate reality is that all dogs can catch this condition, and well over 10% of dogs will suffer from at least one bout of this illness in their lifetime.

Common treatments include antibiotics, IV fluids, and potassium and electrolyte supplements.

ASK A VET: Does Hypoallergenic Dog Food Really Work, and Why?

4. Whipworms Dog Whipworm in Dog Poop

The whipworm is especially dangerous as its eggs can survive in just about any environment, from water and food to soil and bedding.

The eggs can also survive for years without a host.

“Once in the environment, the eggs are very resistant to drying, temperature extremes, and ultraviolet radiation. They can remain viable in the environment for years. Animals are exposed when they ingest the eggs from the ground and soil or from eating the stool of an infected animal.”

– Dr. Rick Marrinson, Longwood Veterinary Clinic, Florida

One of the more sly parasites, there are often few outwardly visible symptoms of whipworms.

However, extreme cases can lead to serious infection and death.

Most veterinarians advise whipworm checks to take place at least once annually.

Symptoms of this parasite include:

  • Dehydration
  • Anemia
  • Bloody diarrhea in dogs

Any age, breed, and size of dog can contract whipworm.

It’s for this reason that hygiene must reign supreme when trying to prevent a case of whipworm.

The treatment for whipworm is a parasitic dewormer.

5. Roundworms

Bloody Diarrhea in Dogs - Helminths ClassificationThe roundworm can produce up to 85,000 eggs per day.

Initially, the eggs are ingested by the dogs, where they will progress into larvae before making their way to the digestive tract.

It’s here that these light-colored worms roam freely, feeding off of the partly digested matter.

This may seem less dangerous than a blood-sucking parasite, but when the number of these worms grows, it can cause a life-threatening blockage.

Symptoms of a roundworm infestation in your pet can include:

Most commonly, puppies are infected by their mother, either just before birth or while nursing.

Roundworms are tricky little devils and can live dormant in dogs for their entire lives.

They could also attack and cause incredible health issues.

Similar to other types of worms, the treatment for this parasite is a parasitic dewormer.

RELATED: Can Humans Get Worms From Dogs?

6. Changes in Diet

A change in diet can cause health issues, most notably when changing to a nutritionally deficient food.

However, issues can occur in sensitive dogs as well or due to food intolerances and allergies with even the most minor change.

Signs that your dog's new diet is not agreeing with him include:

  • Vomiting
  • Bloody diarrhea in dogs
  • Flatulence
  • Weight Loss
  • Scratching incessantly

Any dog can suffer from an adverse reaction to changes in its diet.

The trick is to work out whether or not this is a temporary change or whether the new food is harmful to your dog.

It's best to speak with your veterinarian about the best way to treat your dog's food intolerance issue.

Some treatment options may include:

  • Revert to old food if possible
  • Allergy testing
  • Conduct an elimination diet

7. Inflammatory Bowel Disease (IBD)

In essence, inflammatory bowel disease in dogs (IBD) is the doggy version of irritable bowel syndrome (IBS) that is found commonly in the human population.

This condition is generally caused by the body reacting adversely to normal bacteria in the gut and instigating a defense response that causes inflammation of the bowel.

Common symptoms of Inflammatory Bowel Disease include:

  • Bloody diarrhea in dogs
  • Lethargy
  • Flatulence
  • Gurgling stomach
  • Dull coat
  • Weight Loss
  • Vomiting

As with humans, little is known as to what causes this condition.

The most likely cause is food sensitivity and allergies.

Treatments include anti-inflammatory medication and diet modification (here's an IBD-friendly recipe).

Experts have also been looking for more ways to treat IBD in dogs in the form of probiotics.

“We are studying the clinical, microbiological, and anti-inflammatory effects of this probiotic in the treatment of IBD. Current treatments for IBD include anti-inflammatory drugs, some of which have serious side effects and do not address the underlying basis for the disease, the altered microbial composition.

“Probiotics offer an attractive physiologic and nontoxic alternative that effectively protects against and treats IBD.”

Dr. Albert E. Jergens, Primary research investigator

8. Rectal Injuries

Rectal injuries are usually caused by your dog eating something that he shouldn’t have, for instance, a piece of bone, rock, or part of a stick.

The indigestible object will pass through the digestive tract and may cause injury to the surrounding areas.

Symptoms include:

  • Bloody diarrhea in dogs
  • Pain in stomach
  • Sensitivity to movement or touch
  • Decreased appetite
  • Vomiting

Incredibly playful dogs and those who will put anything in their mouths are the most likely to suffer from this type of injury.

Treatments for rectal injuries will depend on the injury itself but could include surgical removal of scar tissue in extreme cases or antibiotics if an infection takes place.

RELATED: Dog Has Diarrhea? 9 Ways to Prevent and Treat It

Other Possible Reasons for a Dog's Bloody Diarrhea

Apart from what we have mentioned above, there are other possible reasons why your dog's diarrhea appears to be tinged with either fresh, red blood or a black one.

Most of the following causes shouldn't be a cause for concern as they will (and should) go away after a while.

If not, then a visit to the vet is necessary.


Frequent changes, such as traveling or moving, going to a kennel, or the presence of a new pet in the house, can be stressful for a dog.

The result may cause colitis with mucous and bloody stools.

Overeating and inadequate diet

Overfeeding, spoiled food, a sudden change in the dog's diet, and food intolerance may irritate a colon and cause mucous diarrhea and bloody stools.

Rectal polyp

If the polyp is present in the dog's rectum, well-formed stools may pass over it and cause the occurrence of fresh blood on the feces' surface.

Use of NSAIDs

Regular consumption of aspirin or another medication from the NSAID group may cause ulcers in the dog.

The ulcer then starts bleeding, and black, tarry feces will appear as a result.


Giving Pepto-Bismol to dogs to settle their stomach is not that rare, but this drug may temporarily result in black stool's occurrence.

This is not melena, and the feces should turn back to normal shortly after consumption stops.

Ingestion of blood

In some situations, a dog's bloody feces occur when the dog ingests blood after nose bleeding, mouth injury, or licks a bleeding wound.

Complications after surgery

If the black stool occurs 24 to 72 hours after the surgery, internal bleeding should be suspected. You must urgently take the dog to the vet.

Blood clotting disorder

This condition might occur after taking rat poison. This is a potentially fatal condition, and it is necessary to ask for emergency veterinary assistance.


Cancer is fairly common in elderly dogs and can sometimes cause bloody diarrhea.

It is required to take the animal to the vet as soon as you notice a dark stool.

My Dog Has Bloody Diarrhea - Causes and Treatment

What To Do If Your Dog Has Bloody Diarrhea

Seeing blood in your dog's stool can be a medical emergency, so it’s best to consult your vet right away.

If left untreated, this condition could become fatal.

Do not attempt to treat this yourself, especially if there is no diagnosis yet.

Pay attention to the changes in his behavior and eating habits.

Inspect your dog's poop closely. What does it look like? Does it have a strong smell?

If possible, write this in detail so you won't forget. You can also take pictures from different angles to be shown later to the vet.

The best possible thing, though, if you can, is to take with you a stool sample. 

Collecting feces for testing before visiting the vet hospital is a practical option and can speed up the diagnosis process.

Veterinary Diagnosis of Dog Diarrhea

No matter what the reason behind your dog's bloody diarrhea, an urgent vet visit is mandatory.

They will do a couple of tests to pinpoint the exact cause to jumpstart the treatment plan.

After looking at the picture or analyzing the stool sample, the following additional tests might be done to confirm the diagnosis:

  • Blood testing
  • Urinalysis
  • Examination by X-rays or Ultrasound
  • Tissue biopsy
  • A fecal occult blood test

In some cases, the veterinarian may just recommend a different diet for several days.

Water may also be either prohibited or recommended to avoid dehydration or septic shock.

On the other hand, medications or surgery can be the only option in more severe cases.

Before starting with therapy, it is recommended to avoid feeding the animal at least 12 to 24 hours after the blood is noticed for the first time.

That is the way to let the intestines recover as much as possible.

At times, bloody diarrhea doesn’t readily disappear and might even need continuous treatment. 

Your vet will instruct you on how to treat bloody diarrhea in dogs, especially at home.

Causes of Bloody Diarrhea in Dogs with dog in check-up

When To Bring Your Dog to the Vet

A bout of diarrhea isn’t unheard of and can occur from something as simple as a change to your dog’s diet.

It may also happen if he has eaten something that he shouldn’t have.

A small case of diarrhea is nothing to worry about. But, when blood begins to appear, there could be something more sinister afoot.

And apart from the blood, other symptoms to watch out for are:

If your dog is experiencing these symptoms, head to or phone your vet immediately.

They will be able to weigh up the different symptoms, make a diagnosis over the phone, and judge whether further medical treatment is required.

And remember: do not rely on internet articles for the assessment!

RECIPE: Homemade Dog Food for Diarrhea

How to Prevent Bloody Diarrhea in Dogs

As always, preventing bloody diarrhea is better than treating it.

Because there are a large number of possible causes, the best way to prevent bloody stools is to keep your dog healthy and away from toxins, scraps, and any foreign objects.

Remember the following pointers to keep your pup's poop firm and blood-free!

  1. Provide Fido with a healthy, balanced diet.
  2. If you're switching them to a new diet, do so gradually.
  3. Be sure to exercise them regularly.
  4. Keep Fido away from toxins and dangerous foreign objects.
  5. Monitor their level of stress; keep them stress-free!
  6. Prevent intestinal parasites; use dewormers.
  7. Taking care of timely vaccination.
  8. Visit the vet regularly.

Bloody Diarrhea in Dogs with dog in check-up

FAQs about Bloody Diarrhea in Dogs

Is bloody diarrhea in dogs an emergency?

Bloody diarrhea in dogs or vomiting is an emergency that is potentially fatal if left untreated.

If it is fresh blood (hematochezia), it should be treated as an emergency since your woofer could die from dehydration.

A concern could be present if there are more than 2 occurrences, so you should contact the vet immediately.

What Can I Give My Dog for Bloody Diarrhea?

When you notice your pup has bloody diarrhea but don't see any other symptoms, it may not be an emergency.

You can try giving not giving your dog food for between 12 and 24 hours. After that, only give him a bland diet (a.k.a. rice and boiled chicken.)

If this doesn't ease your dog's condition, you will need to take him to a doctor of veterinary medicine.

The most important thing is to ensure that your dog gets enough water. That should be consistent throughout any dietary changes.

Always take your dog to the vet if the symptoms persist. Bleeding may indicate a more serious problem. It is essential to discover the cause of the bloody poop to care for your dog's overall health.

What color is parvo poop?

As more blood enters the intestines, the parvo stool should initially be a light yellow and gradually turn darker.

In the later stages, it might change from yellowish brown to dark red to almost black.

Parvovirus poop can occasionally contain mucus, which gives it a thick, gooey texture.

Why Does My Dog Have Diarrhea But Is Acting Normal?

Sometimes, your dog may have bloody diarrhea or just diarrhea but still act normal. In this case, the stomach problems are likely due to a less serious issue.

However, it's always advisable to consult your vet whenever there are new and alarming things happening to our dogs.

Can Dog Food Cause Bloody Diarrhea?

Yes, if your dog eats the wrong thing, this can cause issues with his digestive tract. That, in turn, can lead to bloody diarrhea.

For example, sudden dietary changes can irritate your dog's stomach.

Your pup's intestines may also become irritated if your dog eats something he shouldn't or doesn't typically eat. This is called dietary indiscretion.

Eating foreign bodies, such as plastic or clothes, is a common possibility. This can lead to intestinal inflammation as well. Both irritation and inflammation can cause bloody diarrhea.

Can I give my dog Pepto for bloody diarrhea?

Giving most dogs Pepto-Bismol (bismuth subsalicylate) is safe.

Dr. Jerry Klein, the chief veterinarian for the AKC, claims that he only rarely advises it.

The drug's salicylates have the potential to cause gastrointestinal bleeding.

The bismuth can also cause the feces to turn black, which might mask any subsequent gastric bleeding.

Are Antibiotics Safe for Bloody Diarrhea in Dogs?

When your dog has bloody diarrhea and vomiting, one of the most recommended treatments is antibiotics.

They are proven to be very effective when it comes to getting rid of those bacteria. 

However, there are some vets who discourage the intake of antibiotics.

While they are reliable medications, they can also eliminate the “good” bacteria in a dog’s gut and later disrupt their metabolism, nutrition, and immune system.

Bloody Diarrhea in Dogs: Before You Go…

As fur parents, bloody diarrhea in dogs can sometimes be scary.

You may not know what to do at first.

Some dog owners would wait it out and see what happens the next time their dog poops.

However, always remember that bloody diarrhea in dogs is a serious condition, and it shouldn’t be taken lightly.

If the problem continues along with vomiting and low energy levels, you ought to rush your pooch to the nearest vet.

Once treated, the vet will tell you how to treat bloody diarrhea in dogs continuously at home.

Our dogs have less control over what they put into their mouths.

So, the best way to prevent this from happening is to monitor what your pooch eats.


The 8 Causes of Bloody Diarrhea in Dogs

Dana is a qualified veterinarian with background in animal care and training sciences and an avid writer on the topics of dog health. Her range of expertise is wide but her primary focus in on animal nutrition and specifically dog foods.