Bloody Diarrhea in Dogs

Causes, Treatment, and Prevention

How to Prevent Bloody Diarrhea in Dogs

The Spruce / Alison Czinkota

Bloody diarrhea is a temporary or chronic ailment in dogs and usually indicates an underlying health issue. There is a wide range of causes of bloody diarrhea, including infectioncancerulcers, and stress. A vet will diagnose bloody diarrhea by examining the dog's stool and then determining any possible underlying causes. Treatment depends on the reason for bloody diarrhea, and the prognosis is relative to its severity; it can be resolved with medication or potentially surgery

What Is Bloody Diarrhea?

Bloody diarrhea (hematochezia) is the mixture of loose, watery stool and blood. The blood can enter the stool at any point in the digestive process, beginning in the mouth and ending at the anus. If your dog has bloody diarrhea, it is likely to be experiencing an underlying infection, disease, or gastrointestinal injury.

Symptoms of Bloody Diarrhea in Dogs

Bloody diarrhea is usually symptomatic of another underlying health problem.


  • Blood in stool
  • Blood in vomit
  • Weakness
  • Lack of appetite

Blood in your dog's diarrhea can be attributed to many illnesses. If the blood has been partially digested, it will resemble coffee grounds and suggest an issue in the lower intestines. If the blood is from the upper intestine or colon, it will look streaky and red. Tarry, dark blood in diarrhea is likely the result of bleeding in the stomach. There may be other, non-specific symptoms accompanying your dog's bloody diarrhea, but they will be relative to the condition causing diarrhea. Visit your vet as soon as you notice blood in your dog's stool.

Causes of Bloody Diarrhea

Many things, ranging in severity, can cause bloody diarrhea in dogs.

  • Stress: Stress can cause a dog's bowels to leak excess fluid and blood from inflammation. This is often referred to as stress colitis and is often accompanied by ulcers. Any inflammatory condition affecting the bowels can cause bloody diarrhea. 
  • Intestinal Parasites: Worms and protozoa, such as hookworms and Giardia, can cause bloody diarrhea. Parasites often feed off and irritate the intestinal wall.
  • Bacterial and Viral Infections: Infections like SalmonellaE. coli, and parvovirus, can cause bloody diarrhea. 
  • Trauma: If a dog experiences an injury or has had surgery on its digestive tract, it may have bloody diarrhea. Bloody diarrhea may also occur when a dog eats an undigestible object and it becomes stuck in the digestive tract.
  • Toxins: Ingestion of poisons or food that is considered toxic to a dog may create inflammation and bleeding, leading to bloody diarrhea.
  • Anal Gland Problems: Anal glands are located at the sides of the anus, and if they become infected, impacted, or inflamed, blood may be present in the stool. Anytime a dog strains to defecate it could burst small blood vessels around the rectal area.
  • Organ disease: Diseased, vital organs may lead to bloody diarrhea. The pancreas plays a vital role in digestion, and bloody diarrhea may result if it becomes inflamed or doesn't work correctly. Severe liver disease and renal disease may also cause bloody diarrhea.
  • Cancer: Many kinds of cancer can affect the digestive tract and cause bloody diarrhea.
  • Blood clotting disorders: Some dogs with clotting disorders may have blood in their stool.

Diagnosing Bloody Diarrhea in Dogs

A vet will diagnose bloody diarrhea by inspecting your dog's stool. If your vet can only find a small amount of blood, they may perform a test called a fecal occult blood test, which will indicate its presence.

Diagnosing the underlying cause of a dog's bloody diarrhea requires a complete health history review and physical examination, alongside diagnostic tests like blood analysis, urinalysis, imaging, tissue biopsies, and more.

Treatment & Prevention

Depending on the cause of bloody diarrhea, treatments will vary. Surgical intervention may be necessary if a tumor or foreign object obstruction is causing the bloody stool. You may need to make changes to your dog's diet to increase fiber intake or reduce inflammation in addition to administering prescription medication. Fluids and blood transfusions are sometimes necessary for dehydrated or anemic dogs. The treatment plan for your dog's bloody diarrhea will vary widely, depending on its cause.

The best ways to prevent a dog from developing bloody diarrhea are to make slow food transitions, keep foreign objects and toxins out of reach, monitor its stress level, use intestinal parasite preventatives, and have regular check-ups with a veterinarian.

Prognosis for Dogs With Bloody Diarrhea

Generally, bloody diarrhea is highly treatable, but the prognosis varies based on the cause of the illness. Once your dog's underlying health issue has been treated effectively, you must allow its inflamed intestines to rest and heal.

  • How do I treat bloody diarrhea in dogs?

    Before you can treat diarrhea, you need to determine the reason for your dog's illness. The cause will determine the cure. Bring your dog to the veterinarian as soon as you notice blood in your dog's stool.

  • What does bloody diarrhea look like in dogs?

    Bloody diarrhea can appear bright red and accompanied by mucous or it can appear dark and tarry. The color of the blood will help your vet diagnose its underlying cause.

  • How long does bloody diarrhea last in dogs?

    The duration of bloody diarrhea depends on its cause and the success of its treatment.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.