Black, slimy poop in your dog is worrying, and it’s natural to want to know right away whether it’s serious. Dark stool coated in mucus can sometimes be minor, but it can also point to a problem that needs immediate attention, so it’s worth taking seriously.
The most important thing to know is that stool that is black, sticky, and tar-like is a different matter from stool that is simply dark. If your dog is also vomiting, weak, refusing food, or has pale gums, call your vet or an emergency clinic right away.
Even if your dog seems fine, black stool that repeats or lasts more than a day deserves a vet’s opinion.
We explain how to tell what type of black, slimy stool you’re dealing with, which warning signs are emergencies, and what to do.
Table of Contents
Black and Slimy Dog Poop: Why It Happens
Black, slimy dog poop may indicate irritation in the digestive tract, but it can also be a sign of gastrointestinal bleeding. The slimy coating may be mucus produced by the intestinal lining in response to inflammation, infection, parasites, or dietary irritation.
However, if the stool is genuinely black, especially if it is sticky or tar-like, it may contain digested blood from bleeding in the stomach or upper intestines. Certain medications and underlying illnesses can also contribute to gastrointestinal bleeding.
Is Slimy Black Stool the Same as Melena?
Not always, but the two can overlap. Mucus is a protective coating the gut produces, and it can wrap around stool of any color.
Melena is something different: dark stool that gets its color from digested blood and has a tar-like stickiness. Because sticky melena can itself look slippery, it can be hard to tell the two apart by feel alone.
Smell is a helpful clue, since melena tends to be far more pungent than ordinary mucus-coated stool.
Dietary Indiscretion
Eating something unusual can irritate a dog’s digestive tract and lead to mucus-covered stool.
A dog may develop loose stool after eating garbage, spoiled food, rich foods, table scraps, or another food that differs significantly from its normal diet.
Certain foods or ingested substances can also temporarily darken the stool.
If the stool is truly black rather than simply dark brown, however, dietary indiscretion should not automatically be assumed to be responsible.
Read more: Black dog poop (Causes and treatment)
Gastrointestinal Bleeding
One important possibility when a dog’s poop is black and slimy is gastrointestinal bleeding.
Blood that originates in the stomach or upper small intestine can be digested as it moves through the digestive tract, producing black stool known as melena. The stool may appear particularly dark, sticky, or tar-like rather than simply brown.
Mucus may also be present when the digestive tract is irritated, although mucus itself does not indicate where bleeding is occurring.
A dog with gastrointestinal bleeding may also develop vomiting, poor appetite, weakness, abdominal discomfort, or pale gums.
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Colitis
Colitis refers to inflammation of the colon and is a common reason dogs produce mucus-covered stool.
Dogs with colitis often pass frequent, small amounts of loose stool containing mucus. There may sometimes be fresh red blood, particularly when the lower digestive tract is inflamed.
However, colitis more commonly causes red blood or blood streaks rather than genuinely black, tar-like stool. If the stool itself is black, another source of discoloration or bleeding may need to be considered.
Sudden Dietary Changes
Changing your dog’s food too quickly can cause temporary digestive upset.
The intestinal tract may respond with softer stool, increased mucus, gas, or diarrhea. Some dogs may also have changes in stool color depending on the new food.
A gradual transition between foods is generally easier for the digestive system than an abrupt change, but persistent black stool should still be evaluated rather than automatically attributed to the diet.
Intestinal Parasites
Some intestinal parasites can irritate the digestive tract and contribute to mucus, diarrhea, changes in appetite, or weight loss.
Parasites are particularly relevant in puppies and dogs that have significant exposure to contaminated environments. Depending on the parasite involved, intestinal bleeding can also occur.
Black stool does not prove that parasites are present, so fecal testing may be needed when parasite infection is suspected.
Gastrointestinal Infection or Inflammation
Infections affecting the digestive tract can cause diarrhea, mucus, abdominal discomfort, vomiting, and changes in appetite.
Some infections primarily affect the colon and produce mucus and frequent bowel movements, while more extensive gastrointestinal disease can cause additional symptoms.
If the stool is genuinely black, the veterinarian may need to determine whether bleeding is occurring in addition to the inflammation or infection.
Certain Medications or Substances
Some medications and substances can change the appearance of stool.
Certain treatments can irritate the gastrointestinal tract, while substances such as activated charcoal can make feces appear black. Some medications may also increase the risk of gastrointestinal ulceration or bleeding in susceptible dogs.
If your dog’s stool changed after starting a medication or supplement, tell your veterinarian rather than assuming the color change is harmless.
Do not give human medications to your dog unless a veterinarian has specifically instructed you to do so.
Related: Dog pooping in the house all of a sudden (Here’s why)
Something That Has Darkened the Stool
Black-looking stool is not always caused by blood.
Foods, supplements, medications, or other ingested substances can sometimes make feces appear unusually dark. The challenge is that it can be difficult to distinguish simple discoloration from melena at home.
If the stool is distinctly black, sticky, or tar-like, particularly if it continues to occur, veterinary advice is appropriate even when your dog otherwise seems well.
A More Serious Gastrointestinal Problem
Less commonly, black and slimy stool can occur with more significant gastrointestinal disease.
Foreign objects, severe gastrointestinal inflammation, ulcers, tumors, and other disorders can cause changes in bowel movements and, in some cases, gastrointestinal bleeding.
These conditions are not equally likely in every dog. Their likelihood depends on the dog’s age, history, other symptoms, and examination findings.
Related: Dog pooping bloody mucus but acting normal (Here’s why)
Dog Poop Is Black and Slimy but Acting Normal
A dog with black and slimy poop may continue eating, drinking, playing, and behaving normally, particularly if the problem has only occurred once.
Normal behavior is reassuring, but it does not completely rule out an underlying gastrointestinal problem. Dogs can sometimes appear well during the early stages of illness.
If the stool is genuinely black or tar-like rather than simply dark brown, monitor closely and contact your veterinarian for advice, particularly if the abnormal stool happens again.
Dog Poop Is Black and Slimy With Diarrhea
Black, slimy poop accompanied by diarrhea can occur when the gastrointestinal tract is irritated.
Mucus is particularly common when the colon is inflamed, but genuinely black stool raises a separate question about whether digested blood may be present.
Frequent diarrhea can also cause dehydration, especially in puppies, older dogs, or dogs that are vomiting or not drinking normally. Persistent diarrhea, weakness, poor appetite, or worsening symptoms should be evaluated by a veterinarian.
Dog Poop Is Black and Slimy With Vomiting
Vomiting together with black, slimy stool deserves closer attention.
This combination can occur with significant gastrointestinal irritation, ulcers, gastrointestinal bleeding, dietary problems, or other digestive disorders. Repeated vomiting can also lead to dehydration.
If your dog cannot keep water down, becomes weak, develops abdominal pain, or repeatedly produces black stool, contact a veterinarian promptly.
Dog Poop Is Black and Slimy With Loss of Appetite
A reduced appetite can be important when it occurs alongside black stool.
Dogs may temporarily eat less when their digestive system is upset, but loss of appetite can also occur with pain, nausea, gastrointestinal inflammation, bleeding, or other illnesses.
If your dog refuses food and also has repeated black stool, vomiting, weakness, or abdominal discomfort, veterinary assessment is warranted.
Dog Poop Is Black and Slimy: What to Do
If your dog’s poop is black and slimy, contact a veterinarian immediately, as black stool can indicate digested blood from bleeding in the stomach or upper intestines.
The slimy coating may be mucus associated with intestinal irritation, inflammation, or infection. Do not assume the change is harmless, even if your dog is still eating and behaving normally.
When to Seek Emergency Veterinary Care
Contact your veterinarian if your dog’s poop is black and slimy, particularly if the stool is sticky or tar-like or if other symptoms develop.
Seek veterinary attention if you notice:
- Repeated black or tar-like stools
- Frequent or severe diarrhea
- Vomiting
- Loss of appetite
- Significant lethargy or weakness
- Pale or unusually light-colored gums
- Abdominal pain
- A swollen or distended abdomen
- Signs of dehydration
- Weight loss
- Difficulty standing or walking
- Unexplained bruising or other bleeding
- Suspected medication or toxin ingestion
- Suspected foreign-object ingestion
- Symptoms that are rapidly worsening
Seek urgent veterinary care if your dog collapses, becomes severely weak, develops significant abdominal pain or swelling, repeatedly vomits, or shows signs of substantial bleeding.
Black and Slimy Dog Poop: Treatment
Veterinary treatment is directed at the underlying cause and may involve supportive care for dehydration, dietary management, treatment of gastrointestinal inflammation or infection, management of gastrointestinal bleeding or ulceration, parasite treatment when appropriate, or adjustment of medications when medically necessary.
More serious cases may require hospitalization, treatment for blood loss, removal of a foreign object, surgery, or further treatment for an underlying gastrointestinal disorder.
Key Takeaway
Dog poop that is black and slimy can have several explanations, and the distinction between dark-brown stool and genuinely black, tar-like stool is particularly important.
The slimy material is often mucus produced by an irritated intestinal lining, but the black coloration may require further consideration.
If your dog is otherwise acting normally and the change happens only once, the situation may be less concerning than persistent black stool accompanied by vomiting, diarrhea, poor appetite, weakness, or abdominal pain.
However, genuinely black, sticky, or tar-like poop can indicate digested blood. If the unusual stool persists, returns repeatedly, or occurs with other signs of illness, veterinary assessment can help determine whether your dog needs specific treatment.