Melena in Dogs: Causes, Signs, and Emergency Care | PawAI Lab

Melena in dogs is the medical term for black, tarry stool caused by digested blood from the upper gastrointestinal tract, and it is a sign that requires prompt veterinary evaluation.

Quick Answer

Melena refers to black, tarry, foul-smelling stool that results from digested blood passing through the upper gastrointestinal tract. The blood originates in the stomach or small intestine and is broken down as it moves through digestion, which turns it dark and sticky. Melena in dogs can be caused by ulcers, certain medications, foreign bodies, or bleeding disorders, and it may signal serious internal bleeding. Because melena can indicate a life-threatening condition, it should be treated as an emergency and evaluated by a veterinarian without delay.

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What Does Melena Look Like?

Melena has a characteristic appearance that sets it apart from ordinary dark stool.

• Uniform black or very dark color throughout the stool
• A shiny, sticky, or tar-like consistency that may cling to surfaces
• A strong, unusually foul odor
• A loose or unformed texture rather than firm, well-shaped stool

The sticky, tar-like quality and the strong smell are key features of melena. Ordinary dark brown stool that is firm and lacks a foul odor is usually not melena. A photo can document the color and texture, but it cannot confirm that the dark color is digested blood. A veterinarian uses examination and testing to confirm the source.

What May Cause Melena in Dogs?

Melena results from bleeding in the upper digestive tract, where blood is digested before it appears in stool. Several conditions can cause this bleeding.

• Gastrointestinal ulcers. Ulcers in the stomach or small intestine can bleed slowly. They may develop from underlying illness, stress, or other conditions and often produce black stool, sometimes with vomiting or reduced appetite.
• Certain medications. Nonsteroidal anti-inflammatory drugs (NSAIDs) intended for humans, such as ibuprofen, can irritate the stomach lining and cause ulcers or bleeding in dogs. NSAIDs should never be given to a dog without veterinary guidance. Products containing bismuth and iron supplements can also darken stool through a color change rather than bleeding.
• Foreign bodies. Swallowed objects can irritate, scrape, or perforate the digestive lining and cause bleeding that appears as melena.
• Bleeding disorders (coagulopathy). Conditions that affect blood clotting can lead to bleeding anywhere in the digestive tract, including the upper GI tract.
• Tumors or masses. Growths in the stomach or intestines can bleed and contribute to melena.
• Toxins. Certain toxins, including rodenticides that affect clotting, can cause internal bleeding that may appear as black stool.

Melena always warrants veterinary evaluation, because the underlying bleeding can be serious regardless of the specific cause.

What Details Should the Owner Check?

Because melena may require immediate action, gathering details quickly is important.

• Whether the stool is shiny, sticky, or tar-like and whether it has a strong odor
• Whether stool is loose or formed
• Any vomiting, especially if dark or coffee-ground-like
• Appetite, energy, weakness, or collapse
• Pale gums or rapid breathing
• How many stools are affected and when the change started
• Any medications, supplements, or human products given, especially NSAIDs
• Any unusual items the dog may have eaten or possible toxin exposure
• Whether the dog has an existing condition or is on medication

Puppies, seniors, and small dogs can deteriorate quickly with internal bleeding and need the fastest possible evaluation. Note the time the melena was first observed and bring packaging for any medications given.

What Should the Owner Do Next?

Because melena can indicate serious internal bleeding, prompt action is essential.

• Contact a veterinarian or emergency clinic immediately if stool is black, tarry, or foul-smelling.
• Do not wait to see if it resolves on its own.
• Do not give any human medications, including NSAIDs, stomach remedies, or home remedies.
• Keep the dog calm and limit food until advised.
• Note the time the melena was first observed.
• Bring a list of all medications and supplements, and packaging if possible.
• Bring a fresh stool sample if available and easy to collect.

A veterinarian can perform an examination, blood work, and other tests to locate the source of bleeding and determine appropriate treatment.

When to Contact a Veterinarian

Melena is treated as an emergency. Seek immediate veterinary care if you observe any of the following:

• Black, tarry, or sticky stool (melena)
• Vomiting that is dark, coffee-ground-like, or contains blood
• Weakness, collapse, or pale gums
• Abdominal pain, bloating, or restlessness
• Rapid breathing or a rapid heart rate
• Melena following ingestion of a medication, toxin, or foreign object

Signs that warrant a prompt veterinary call, even if the dog seems well:

• Black stool clearly linked to a medication like bismuth, with no other signs
• One dark stool after a known dietary cause, with the dog acting normally

Because melena cannot be reliably distinguished from a benign dark stool at home, confirming the cause with a veterinarian is always advisable.

FAQ

What does melena mean in dogs?

Melena is the medical term for black, tarry, foul-smelling stool caused by digested blood from the upper gastrointestinal tract. It is not a diagnosis itself but a sign that bleeding has occurred in the stomach or small intestine. A veterinarian can determine the underlying cause through examination and testing.

Can NSAIDs cause melena in dogs?

Yes. Nonsteroidal anti-inflammatory drugs (NSAIDs) intended for humans, such as ibuprofen, can irritate the stomach lining and cause ulcers or bleeding in dogs, which may appear as melena. NSAIDs should never be given to a dog without veterinary guidance. Always report any medications a dog has received to a veterinarian.

Is melena always an emergency in dogs?

Melena is treated as a potential emergency because it can signal serious internal bleeding. Some dark stools are caused by medications or diet rather than blood, but the two cannot be reliably told apart at home. A veterinarian should evaluate black, tarry stool without delay.

How is the cause of melena found?

A veterinarian may use a physical examination, blood tests, fecal tests, imaging, or endoscopy to locate the source of bleeding. The specific approach depends on the dog's history and other signs. Owners can help by bringing a list of medications, notes on possible ingestion, and a stool sample if available.

Final CTA

Try the PawAI Lab Poop Scanner to organize visible stool features and review general next-step guidance.

Sources

• Merck Veterinary Manual. Gastrointestinal Ulcers in Small Animals.
• Cornell University College of Veterinary Medicine. Gastrointestinal Bleeding in Dogs.
• VCA Hospitals. Melena in Dogs.
• American Veterinary Medical Association (AVMA). Pet Poison Prevention and Gastrointestinal Health.

Disclaimer

This article and the PawAI Poop Scanner provide general educational guidance based on visible information. They cannot diagnose digestive disease, infection, parasites, or internal bleeding and do not replace examination or testing by a veterinarian.