Updated: Oct 15
Key points
Bright red blood in dog poop (hematochezia) usually comes from the lower digestive tract, while black, tarry stool (melena) is digested blood from higher up.
A single small streak in a happy, eating, energetic adult dog is often not an emergency – but any blood in a puppy, large amounts, or blood with vomiting, lethargy, or pale gums needs a vet now.
Common causes of blood in dog stool include stress colitis, parasites, parvovirus, AHDS, toxins, and ulcers.
If you’ve found blood in your dog’s poop, don’t panic – but don’t ignore it either. A dog pooping blood is actually quite common and sometimes just a fluke. Think occasional red streaks in the stool, not something out of a horror movie. The difference usually comes down to the amount of blood, the color of the blood, and any accompanying symptoms.
Over my 35 years as a veterinarian, I've received thousands of phone calls from pet parents worried because they saw blood in their pet’s stool. Most of the time, it turned out to be completely harmless or needed only mild treatment.
What blood in dog poop looks like: bright red vs. dark and tarry
Bright red blood in dog poop
If you see bright red blood in your dog's stool, this is called hematochezia. The bright red blood in dog stool indicates the blood hasn't traveled far through the body and is undigested, which gives it that bright red color. This type of bleeding usually begins in the rectum, colon, or anus.
Black or tarry blood in dog poop
If you notice black dog poop or tarry blood in your dog's stool, this is called melena. This blood is coming from higher in the dog’s digestive tract and has been digested. With melena, your dog’s stool may resemble coffee grounds. The Merck Veterinary Manual calls melena a classic sign of bleeding ulcers in the upper digestive tract, but it can also come from other conditions including leptospirosis in dogs.
If you’re not sure you’re seeing blood, try wiping some of the stool on a white paper towel. The redder pigments will then be visible. If you suspect your dog is showing signs of melena, you should contact your veterinarian immediately.
| Bright red blood (hematochezia) | Black, tarry stool (melena) |
Appearance | Fresh red streaks or drops | Dark, sticky, coffee-ground or tar-like |
Source | Lower GI: colon, rectum, anus | Upper GI: stomach, small intestine |
Urgency | Monitor if dog is otherwise normal | Contact your vet right away |
Likely causes | Colitis, stress, parasites, parvo, AHDS, anal glands, tumors | Ulcers, NSAIDs, toxins, clotting disorders, tumors |
Common causes of bright red blood (hematochezia) in dog stool
Parvovirus
Parvovirus is a common cause of bloody diarrhea and bloody stools in puppies. Symptoms may include vomiting, diarrhea, loss of appetite, blood in the stools, and lethargy. If you suspect your dog has contracted parvovirus, see your vet immediately as it can be life-threatening.
Parasites
Intestinal parasites or worms in dogs can also cause blood in the stool. These can include hookworms, whipworms, roundworms, tapeworms, Giardia, and coccidia (protozoans). A regular parasite prevention program can eliminate them.
Intestinal blockages and injuries
Dogs love to ingest anything that looks tasty to them. This can get them into trouble and cause irritation of the colon, punctures of the intestinal walls, intestinal blockages, or diarrhea – and thus, bloody stools.
If you know that your dog has recently swallowed a chicken bone or something else they shouldn't have, then blood in their stool should be a major cause for concern. Talk to your vet about potential treatment options, including surgery to remove the foreign object or blockage.
Hemorrhagic gastroenteritis (AHDS)
While not technically hematochezia, hemorrhagic gastroenteritis (HGE) is sudden, severe bloody diarrhea – now called acute hemorrhagic diarrhea syndrome (AHDS). Owners often describe dog poop like jelly with blood; the Merck Veterinary Manual notes the profuse, jelly-like stool can resemble raspberry jam, and VCA reports it's most common in small and toy breeds, likely involving Clostridium perfringens.
Dehydration and shock can set in fast. If you notice jelly-like blood in dog stool, call a veterinarian immediately, as this condition can be fatal.
Stress colitis
Can stress cause blood in dog stool? Absolutely, extreme stress can also cause bloody stool. Common causes of extreme stress include fireworks, moving, or a new pet or person joining the family. In nervous pups, these events can all cause colitis – bloody diarrhea, sometimes with mucus in dog poop.
Anal gland problems and tumors
Dogs have two scent glands located on either side of their anus, and inflammation or abscesses can result in hematochezia. Colonic, rectal, anal, or anal gland tumors that bleed can also cause hematochezia.
Common causes of black, tarry stool (melena) in dogs
Ingesting toxins
Ingesting toxins like antifreeze or rat poison can cause melena. Also, toxic foods such as grapes, onions, and garlic can send your dog into a medical emergency with black, tarry poop or bloody diarrhea.
Ingesting blood
If your dog licks a bloody injury, has a dental disease that causes bleeding in their mouth, or even swallows the blood from a nosebleed, then their stools will show signs of digested blood.
Blood clotting disorders
Disorders that slow down the clotting of your dog’s blood can range from inherited disorders to acquired disorders. Some infections can cause this too – the Merck Veterinary Manual lists melena among the bleeding problems occasionally seen with leptospirosis.
NSAIDs
Anti-inflammatory drugs can cause ulcers in your dog’s stomach, which can bleed into the digestive system. Your vet will monitor your dog’s health while on these medications, but you should also monitor their feces for signs of blood.
Post-surgery complications
If your dog has had surgery and you notice blood in their stool, contact your vet right away. It could indicate internal bleeding.
Pepto-Bismol
Used to treat diarrhea, Pepto-Bismol may turn your dog’s stool black temporarily. It will return to normal when the medication is completed. It can also cause gastric bleeding, so give it only if your veterinarian recommends it.
Blood in dog poop but acting normal: when to worry
I've also examined many dogs over the years whose worried parents brought them to the clinic because they saw blood in their dog's stool, even though the dog was acting normal. A dog pooping blood but acting normal is a common reason for concern.
Knowing when to worry about blood in dog stool involves determining the amount, color, and whether there are any other signs of illness. If your dog has diarrhea with blood but acts fine – bright and alert, eating, and drinking – a single small episode usually isn't an emergency.
The options are:
Monitor at home (24 hours): one small streak of bright red blood in a vaccinated adult dog that's eating, drinking, and acting normally.
Call your vet: blood recurs, stool turns soft or mucus-coated, appetite or energy dips, or your dog is on NSAIDs.
Go to the ER now: any blood in a puppy, large amounts, jelly-like bloody diarrhea, black or tarry stool, blood plus vomiting or lethargy, pale gums, collapse, or a known toxin or swallowed object.
You should always be concerned about blood in puppy stool. Puppies dehydrate quickly and are susceptible to parvovirus, which can be fatal. As a veterinarian, I saw far more cases of parvovirus in vet school than I have in private practice because of its seriousness.
Not sure if your dog’s poop is concerning? It’s helpful to be familiar with a dog poop health guide.
What the vet will do: diagnosis and treatment
Your dog's treatment will depend on the underlying cause of the bloody stool. Your vet will likely start with a physical exam and a medical history review. Your veterinarian might recommend:
Parasite tests to rule out worms or Giardia
Blood work to rule out anemia, infections, and platelet counts that may affect blood clotting ability
Metabolic or chemistry screening to check liver and kidney function
X-rays to look for foreign bodies in the digestive system and blockages
Ultrasound to look for tumors, check organs, or check for injuries
Endoscopy to examine the upper GI tract
In AHDS, Veterinary Partner notes that vets track the hematocrit (PCV), which rises with dehydration but drops with blood loss. For less serious medical issues, your vet may recommend simple treatments such as extra fluids for dehydration, antiparasitic medication, diarrhea medication, or diet changes.
Probiotics and vitamin injections (particularly Vitamin B12) can also help soothe a sick pup's digestive system. More serious causes – a swallowed object, tumors, inflammatory bowel disease – may require a period of hospitalization with appropriate treatments or even surgery.
Home care and prevention
When you spot blood, it’s always a good idea to:
Take a picture of your dog’s poop
Keep a stool sample
Take note of whether it’s bright red or black, tarry blood
Take note of any other unusual symptoms
If you end up at your veterinarian's office, these notes will help with diagnosis.
Jelly-like bloody diarrhea needs veterinary fluids, not home treatment.
For mild cases managed at home, a bland diet often helps. I usually recommend chicken and rice for basic cases of diarrhea in dogs.
To prevent your dog from having blood in their stool:
Use parasite prevention year-round.
Keep all garbage away from your dog.
Never give your dog cooked bones.
Keep toxic foods out of reach.
When transitioning from one food to another, do it slowly.
Keep your puppy vaccines on schedule.
Basics of blood in dog poop
As you can see, there are many reasons your dog could have blood in their stool. Monitor your dog's stool color and behavior daily. If you see blood in your dog’s poop, talk to your vet to determine the underlying cause and how to move forward with any necessary treatment. Being proactive not only helps you stay on top of your dog’s health, but it also gives them the best prognosis possible if they get sick or hurt.
FAQs
When should I worry about blood in my dog's stool?
Call your vet promptly if there's a large amount of blood, repeated bloody stools, blood with vomiting or lethargy, pale gums, or black, tarry stool. If your dog is a puppy, treat any blood as urgent – puppies dehydrate quickly and are vulnerable to serious diseases like parvovirus, so don't wait it out.
My dog is pooping blood but acting normal – is it an emergency?
Usually not. A single small streak in an otherwise happy, eating, energetic adult dog is often something minor, like stress colitis or a dietary indiscretion. Still, monitor closely for the next day or two, and call your vet if the blood recurs or any other symptoms appear.
What does it mean if the blood is bright red vs. dark and tarry?
Bright red blood (hematochezia) is fresh and usually comes from the lower digestive tract: the colon, rectum, or anus. Dark, black, or tarry stool (melena) is blood digested on its way through, so it comes from the upper digestive tract, such as the stomach, and it warrants prompt veterinary attention.
Can stress cause blood in my dog's stool?
Yes. Intense stress – fireworks, boarding, a move, a new pet or baby – can trigger colitis, an inflammation of the colon that produces soft, bloody, often mucus-coated stool. It usually resolves within days with vet-guided care, like a bland diet and probiotics, but have your vet confirm the cause.
