What Dog Diarrhea Blood Means for Your Pup's Health Gastrointestinal Issues at Their Worst

What Dog Diarrhea Blood Means for Your Pup's Health
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If you find blood in your dog's diarrhea, it may be time to sound the alarm. Find out here some common reasons why blood might be showing up in your dog's stool, and if you'll have to see the vet.

Periodic diarrhea is a common problem for dogs, but if you notice that it looks bloody or tar-like, you should treat it as an emergency. Thanks to their extensive and varied diet, dogs are prone to gastrointestinal issues, but the types that cause bleeding are often more dangerous and a cause for serious concern. Here’s what to do if your dog has diarrhea with blood in it.


When you notice blood in diarrhea, it means that somewhere during digestion an ulcer or other injury has caused bleeding. If this bleeding is in the stomach or small intestine, it is more likely to look like tar and have a strange odor due to partial digestion. If bleeding occurs later in the process, in the colon or rectum, you are more likely to see bright red blood.

In addition to blood in diarrhea, you may also notice that your dog is acting tired, showing a loss of appetite, vomiting, or has a fever. Only a veterinarian can determine what may have caused the bleeding through a physical and tests, so it's important to consult immediately. Depending upon the symptoms, your vet may suggest immediate treatment or hospitalization.

Possible Causes of Bloody Dog Diarrhea

Ulcers and Colitis

While we may be more familiar with ulcers in the stomach, they can occur at any point along the digestive process and often lead to blood in diarrhea.


Several viruses attack gastrointestinal tracts of dogs, including the parvovirus and corona virus, and this damage often leads to bleeding. “Parvo” is highly contagious, and can be fatal, so it’s critical to act fast. Vaccinating new puppies can help your dog avoid the worst of these viruses.


Bacteria may be the most common cause of blood in diarrhea, often inflaming tissues after growing in the intestines. Several common bacteria that affect dogs include salmonella, e-coli, and camplyobacter. These can also infect humans and lead to similar results.


Worms and protozoa can wreak havoc on the gastrointestinal tract and make it difficult for your dog to absorb nutrients. Some common types include whipworms, hookworms, and Giardia, which may enter while eating rotten food or drinking contaminated water.


Sometimes dogs eat plants they shouldn't, or can get into poisons intended for rats and other pests. Warfarin (rat poison toxin) or other poisonous mixtures can lead to blood in your dog’s stool. Keep household chemicals and rodent-killing poisons locked up or out of your dog’s reach.


Unfortunately, blood in diarrhea may also be a sign of a gastrointestinal cancer, which may have already caused substantial damage.

Other conditions

Many other illnesses can lead to bloody diarrhea, such as liver or kidney failure, Addison’s disease, blood-clotting issues, or hemorrhagic gastroenteritis (HGE), which often causes sudden, heavy bleeding and requires immediate veterinary attention.


Your vet will determine treatment once they diagnose the cause of the bleeding. Many conditions will require medications or even surgery. Usually, dogs should not be fed for 12 to 24 hours after the diarrhea, and in some extreme cases, water will even be withheld (paired with intravenous fluid) to let the intestines recover. In all other cases, providing your dog with unlimited water will be crucial to avoid dehydration and septic shock.

Noticing these symptoms early and contacting your vet are key for successful recovery. If treated early, dogs usually respond well to medications treating parasites or bacteria, though some illnesses, such as cancer, may be more challenging to treat.

More on Gastrointestinal Problems

What Causes Gastritis in Dogs and Cats?
Is Your Dog Puking Blood? Here's What You Do
How To Change Dog Food

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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