Bloody diarrhea is not fun for a dog to have nor is it enjoyable for the dog owner to witness or clean up. Diarrhea can be temporary or chronic and the color of the stool may tell us something about the underlying cause of it. Bloody diarrhea is especially concerning for dog owners since blood is not a normal part of feces. It should always be taken seriously because there are serious reasons why blood may be noted in a dog’s stool.
Causes of Bloody Diarrhea in Dogs
Bloody diarrhea containing bright red blood is called hematochezia while stool that contains black blood is referred to as melena. Hematochezia is a result of bleeding in the lower digestive tract while melena starts in the upper digestive tract. Blood that occurs in melena gets digested and turns black before appearing in diarrhea. Bloody diarrhea of both types can be caused by a multitude of things.
- Stress: Just like in people, stress can cause a dog's bowels to leak excess fluid along with blood from inflammation. This is often referred to as stress colitis.
- Intestinal Parasites: Various worms and protozoa, such as hookworms and Giardia, can cause bloody diarrhea. This is because these parasites often feed off of and/or irritate the intestinal wall.
- Bacterial and Viral Infections: Various infections, such as Salmonella, E. coli, and parvovirus can all cause bloody diarrhea.
- Trauma: If a dog experiences some sort of injury or has surgery on the digestive tract it is possible that the dog will have bloody diarrhea as a result.
- Bowel Inflammation: Any type of inflammatory condition affecting the bowels can cause bloody diarrhea.
- Toxins: Ingestion of poisons or any food that is considered to be toxic to a dog may create bleeding issues in the body as a whole or bloody diarrhea in particular due to a variety of effects.
- Anal Gland Problems: Anal glands are located to the sides of the anus and if they become infected, impacted, or inflamed, blood may be present in the stool.
- Straining to Defecate: Anytime a dog strains to defecate it could burst small blood vessels around the rectal area.
- Cancer: Many kinds of cancer can affect the digestive tract and unfortunately cause several issues including bloody diarrhea.
- Dietary Indiscretion: If a dog eats something it doesn't normally eat it may develop some intestinal irritation or inflammation and have bloody diarrhea.
- Ulcers: Stomach and intestinal ulcers can cause diarrhea and bleeding.
- Foreign Bodies: If a dog eats an object that is not digestible it can become stuck or cause trauma in the digestive tract. This can result in bloody diarrhea.
- Side-Effects from Medications: It is not uncommon for medications to have side effects, one of which could be bloody diarrhea.
- Pancreatic Disease: Since the pancreas plays an important role in digestion if this organ gets inflamed or doesn't work properly bloody diarrhea may result.
- Liver Disease: Severe liver disease may cause bloody diarrhea as the liver is unable to function properly.
- Kidney failure: Severe renal disease can cause bloody diarrhea.
- Addison's disease: An uncommon endocrine disorder, Addison's affects the adrenal glands and may cause bloody diarrhea in dogs.
- Blood clotting disorders: Some dogs that have clotting disorders may develop blood in their stool.
Diagnosing Bloody Diarrhea in Dogs
Bloody diarrhea is usually identified by visually inspecting the stool. Bright red blood is quite obvious to see in most stool but black, digested blood may be less apparent. If digested blood or a very small amount of red blood is suspected, your veterinarian may perform a test called a fecal occult blood test that says whether or not blood is detected in the feces.
Diagnosing the underlying cause of a dog's bloody diarrhea requires a complete health history and physical examination and often some combination of diagnostics, which may include fecal examinations, blood work, a urinalysis, imaging (x-rays or ultrasound, for example), tissue biopsies, and more.
Depending on the cause of bloody diarrhea, treatments will vary. Surgical intervention may be necessary for foreign bodies and cancer, dietary changes may be made to increase fiber intake or reduce inflammation, and medications may be used to kill parasites, treat diseases, alleviate symptoms, and provide support. Fluids and blood products are also sometimes needed in pets that are dehydrated or anemic.
How to Prevent Bloody Diarrhea in Dogs
The best way to prevent a dog from developing bloody diarrhea is to make slow food transitions, keep foreign objects and toxins that it may consume out of its reach, monitor its stress level, feed appropriate foods, use intestinal parasite preventatives, and have regular check-ups with a veterinarian.
Fahsbender, Elizabeth et al. Chapparvovirus DNA Found In 4% Of Dogs With Diarrhea. Viruses, vol 11, no. 5, 2019, p. 398. MDPI AG, doi:10.3390/v11050398
Ruotsalo, Kristiina, and Margo Tant. Fecal Occult Blood. VCA Animal Hospitals.