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Blood in Dog Stool – Reasons – What to Do If You Find It – 10 important things you must know

When your dog has bright red blood in dog stool, the issue is called hematochezia. A little bit of bright red can be nothing to worry about and might subside on its own. But if you see large amounts of blood, it’s definitely time to call the vet for a consultation. Don’t wait until morning to call.

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Key Points

  • There are two types of bloody stool: hematochezia and melena.
  • Dark, tarry stool, called melena, has more than one dozen causes.
  • If you find blood in your dog’s stool, call your veterinarian.
Blood in Dog Stool by
Blood in Dog Stool by

The first thing you should do if you find blood in your dog’s stool, whether the stool is formed or loose (like diarrhea), is to call your veterinarian. You can save yourself and your veterinarian time by knowing how to describe your dog’s bloody stool. There are two types: hematochezia and melena.

Hematochezia is bright red blood. This type of bleeding occurs in the lower digestive tract or colon and indicates a specific set of conditions.

If you notice a single streak of red blood in your dog’s stool, and the rest of his poop is normal, it might be a fluke. Consistent bleeding or large amounts of blood indicate a more serious problem. Severe conditions that can cause bloody stool or bloody diarrhea include viral and bacterial infections, parvovirushemorrhagic gastroenteritis, and possibly cancer.

Melena is a dark, sticky, tarry stool, almost jelly-like. This blood has been digested or swallowed, indicating a problem in the upper digestive tract.

Some dogs have darker stool than others, depending on diet and other factors. If it looks darker than normal or shows any major changes in color or appearance, contact your veterinarian. Causes include parasites and liver cancer.

Bloody Diarrhea in Dogs

Written by Adrienne Kruzer, RVT, LVT Reviewed by Jennifer Coates, DVM

Sick puppy
. Lumenphoto / Getty Images

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.What to Do When Your Dog Has Diarrhea

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.1
  • 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.2
  • 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.2

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.

Other Symptoms

Keep an eye out for changes in your dog’s appetite, activity levels, and attitude. Vomiting, diarrhea, appetite loss, weakness, blood in the urine, and difficulty breathing can all indicate serious conditions that require immediate veterinary intervention.

I Noticed Blood in My Pet’s Poop. Should I Be Worried?

I Noticed Blood in My Pet's Poop. Should I Be Worried?

If you see signs of blood in your pet’s poop, there’s no need to panic. But it does mean you should call your veterinarian and schedule an appointment to discuss this new event.

Blood in your pet’s stool is an indication of another, underlying problem. Correct diagnosis of the cause will allow prompt treatment.

Questions You Can Expect at Your Office Visit

When you come in for your office visit being prepared to answer these questions will help us zero in on finding the real problem.

  • How long has there been blood in your pet’s poop?
  • Has this ever happened before?
  • Does your pet also have diarrhea?
  • If so, how long have you noticed the diarrhea?
  • Is your pet vomiting?
  • Is your pet lethargic?
  • Is your pet still eating and drinking?
  • Does your pet roam free?
  • Do you know of anything your pet ate that he shouldn’t have?
Blood in Dog Stool by
Blood in Dog Stool by

How to Correctly Describe the Blood in Your Pet’s Poop

While it may be a bit unpleasant, correctly observing and describing the appearance of the blood in your pet’s poop helps determine the source of the blood. Bright red blood comes from the animal’s lower digestive system, while dark red/black stools indicate an upper digestive problem.

Bright Red Blood in Stools

Hematochezia is the medical term for bright red blood in your pet’s stool. It is fresh blood, most likely from the lower intestines, and often from the colon or rectum. Some causes of hematochezia include:

  1. Parvovirus – A serious virus often found in puppies. Other symptoms of parvo include vomiting, diarrhea, lethargy, and loss of appetite. Prompt treatment is critical.
  2. Parasites – The most common cause of blood in stools. A fecal analysis will identify if parasites are present and the proper treatment based on the organism.
  3. Hemorrhagic gastroenteritis – Usually accompanied by vomiting and diarrhea, and causes large amounts of blood in stools. Dehydration is a danger in this case, and IV fluids and medications are often needed to treat successfully.
  4. Rectal injuries – These can be caused by your pet eating a sharp object which scrapes the lower intestine during digestion or elimination. Anal gland injuries and rectal polyps can also result in bright red blood deposited on stools.
  5. Stress – Changes in your pet’s routine or household can induce colitis with blood and/or mucus in the loose stools.

Dark Red or Black Blood in Stools

Melena is the medical term for dark red or black/tarry stools. Since it is darker in color, it’s often harder to detect. In these cases, the blood source originates higher up the intestinal tract so that by the time the stools are eliminated the blood is almost totally digested. Melena may be caused by:

  1. Blood clotting disorders – Several conditions can cause clotting disorders, as well as your pet eating rodent poison. 
  2. Use of NSAIDS – Your pet can develop gastric ulcers from extended use of these medications.
  3. Post-surgery complication – Call your vet immediately if you notice black, tarry stools up to 72 hours after any recent surgery. This could indicate internal bleeding.
  4. Tumors or cancer – Bleeding tumors or polyps, especially in older pets, can cause dark stools.
  5. Ingestion of blood – Your pet may lick a bloody wound or have a mouth injury that causes it to swallow blood. 

“Blood in your pet’s poop indicates an underlying problem, so it’s important to get your pet to the #vet as soon as you notice it.” TWEET THIS

Diagnosis and Treatment of Bloody Stools

Depending on your description of the bloody poop and your pet’s other symptoms and history, certain tests will help us correctly diagnose the cause so we can come up with a treatment plan. Some of the tests may include:

  • Fecal analysis – Bring a fresh stool specimen to your appointment. We will visually evaluate the blood, as well as run microscopic and parasitic testing on it.
  • X-rays – To check for anything unusual in the abdomen and digestive tract.
  • Blood work – A simple blood draw for a complete blood count, differential and chemical screen to test for inflammation or infection.
  • Visual and physical exam and palpation – To check for any abnormalities that can be seen or felt. 
  • Further testing or surgery as needed 

As a pet parent, you know your pet best and you know when something isn’t quite right. When you see any signs of blood in your pet’s poop it’s time to call your vet.

At South Boston Animal Hospital we love helping pet families stay healthy and happy. If you have noticed blood in your pet’s poop, call right away so we can find the best treatment plan.

When Your Dog Has Blood in His Stool

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Blood in Dog Stool by

If you think your dog is pooping with blood in his stool, you’re likely to understandably be alarmed! When your dog has blood in his stool, this may be caused by a wide range of ailments. Let us help you discern what may be the cause if in doubt, consult with your vet first.

Determining if it truly is blood and what type of blood you’re seeing can help narrow down the possible causes. First, make sure it is blood and that your pet didn’t eat anything unusual that contained red dyes. They could possibly be passing something through their digestive system that they ate, like lipstick or a box of red hot tamales (note: do not let your dog eat hot tamales). 

If you are unsure, try wiping a bit on a paper towel to get a better look. If you find it is blood, you will want to note the color of the blood and call your vet right away. 

There are two types of common issues when a dog has blood in his stool, both of which may mean different causes. 

Bright Red Blood in Stool

When your dog has bright red blood in his stool, the issue is called hematochezia. A little bit of bright red can be nothing to worry about and might subside on its own. But if you see large amounts of blood, it’s definitely time to call the vet for a consultation. Don’t wait until morning to call. 

When combined with lethargy and vomiting, bright red bloody diarrhea could mean your dog has hemorrhagic gastroenteritis (HGE), a severe condition that can be fatal if left untreated. When puppies experience bloody diarrhea, it is possible they have contracted canine parvovirus, which is a potentially fatal viral disease.

The consistency of stool along with the presence of bright red blood can also give some telltale signs of where the root problem is stemming from. If your dog’s stool is normal in consistency and coated with an outer layer of red blood, this could mean that the problem is coming from a low area in the intestinal tract. Diarrhea and soft feces with red blood mixed in may mean that the issue is coming from higher in the intestinal tract.

Causes of Bright Red Blood in Stool 

Dark, Blackish Red, & Tarry Stools

Should you see stool that is dark, blackish-red, and tarry, this means the blood has spent a lot of time in the intestinal tract or has been digested. The issue is either close to or within the stomach. This type of blood in a dog’s stool is called melena and can be difficult to notice for some. If you see radical changes in your dog’s stool, it is best to call your vet just in case it is something serious.

Causes of Dark, Blackish Red, & Tarry Stools

  • Foreign objects
  • Infections
  • Parasites
  • Ulcers
  • Tumors
  • Toxins
  • Inflammatory bowel disease (IBD)
  • Liver disease
  • Kidney failure
  • Reaction to a medication
  • Pancreatitis
  • Addison’s disease
Blood in Dog Stool by
setter/pointer type Hungarian Vizsla purebred dog

If your dog or puppy has contracted parvovirus, you certainly don’t want to inadvertently infect other dogs with this deadly disease. Your vet’s office will take precautions to minimize the spread of disease while treating your dog.

Parvovirus is a disease that every dog should be vaccinated against. Be sure to get your puppy with a healthy immune system vaccinated against canine parvovirus, distemper, canine hepatitis, and rabies as soon as they are 6-8 weeks old. These core vaccinations will help keep them safe from infection when they socialize and interact with other animals.

Be sure to monitor your animal for other symptoms your dog has that occur simultaneously. The symptoms may be an indicator to your vet and help them determine why your dog has blood in his stool. Always call your vet ahead of time instead of bringing them straight to the vet, though if this is an emergency, please find your nearest animal urgent care or 24-hour emergency animal hospital.

Blood in Dog Stool: A Quick Assessment

First, you will want to determine if the red color is actually blood. Ask yourself the following questions:

  1. Did my dog eat a nonfood item that is red, such as crayons or red lip balm?
  2. Was my child eating a cupcake with red icing and shared with my dog?

Human food colored with a copious amount of food coloring, or nonfood items that contain dyes, can color the contents of the gastrointestinal tract as they move through. In most cases, this is harmless. Ask your veterinarian if the suspected ingestion poses any health risks.

Second, look under the hood, er, the tail. An infection near the anus, such as a ruptured anal sac, can cause blood to appear in the stool. Injury to the sensitive rectal tissues can also lead to streaks of fresh blood. While these causes need to be addressed, there is no reason for immediate action in the middle of the night.

Third, ask yourself the following questions:

  1. Is the stool normal in consistency (firm, not loose)?
  2. Is my dog acting normally (eating with normal energy level)?

If the answer to these questions is yes, you can wait until the next day to pursue medical intervention.

Causes of Blood in Stool

Viral and bacterial illness– Dogs are prone to developing irritation in their lower gastrointestinal tract for a variety of reasons. When accompanied by loose stool, anorexia and/or vomiting, an infection is likely the culprit.

Many viral and bacterial agents can cause illness and lead to bloody stool. If untreated, the symptoms can progress to a syndrome called hemorrhagic gastroenteritis (characterized by copious amounts of bloody, loose stool). This condition usually requires hospitalization, so early intervention of gastrointestinal symptoms is helpful to prevent progression.

If you have a sick puppy with blood in the stool, you must ACT FASTParvovirus is common, especially in unvaccinated pups, and can be rapidly fatal is not treated.

Intestinal parasites– Some intestinal parasites can cause bleeding in the lower intestinal tract. Fortunately, heartworm preventatives deworm monthly and will help control infection. But, even dogs that receive regular preventatives can become infected between doses. If there are parasites, your veterinarian will be able to help you devise a treatment schedule.

Foreign body– Dogs will eat just about anything. Nonfood items can become lodged in the GI tract, causing both straining and loose stool. The subsequent damage to the tract, both from the lodged item and the straining, can cause blood to be present. Diarrhea can be noted even with a foreign body, so don’t let the presence of loose stool fool you, especially if you are missing socks.

Immune-mediated thrombocytopenia– This disease is relatively uncommon but can be catastrophic if not caught early. Something triggers the body to attack and consume platelets and the lack of clotting ability can lead to active bleeding in many parts of the body, including the gastrointestinal tract. In some cases, the red blood cells are also attacked, causing anemia. Take a quick peak at your dog’s gum color. If it appears pale instead of pink, immediate medical care should be pursued.

Food allergies– Many dogs become allergic to proteins in food as they age. If the allergy is severe and the offending ingredient is consumed, colitis (inflammation in the lower gastrointestinal tract) can result. This inflammation can lead to damage to the lining of the tract and subsequent blood in the stool. If the symptom resolves and recurs, this may be the cause and a logical course of action determined by your veterinarian should be followed. Do not try to address this on your own, as some diets that are commercially available are not appropriate and may cause more harm.

Blood in a dog’s stool is just a symptom, and the underlying cause needs to be identified and addressed. When accompanied by diarrhea and lethargy, immediate veterinary care should be pursued. If your dog is acting normally, with a good appetite and energy level, it is generally safe to wait until the next day, but keep a close eye on behavior, appetite and stool consistency.

Is your dog pooping blood and mucus? Find out what the cause could be and how to treat blood and mucus in your dog’s stool.