When your dog starts pooping black and refuses to eat, it’s more than just concerning—it could be a sign of something seriously wrong.
We outline the common causes of a dog pooping black and not eating, what you can do at home, and when to seek veterinary help.
Dog Pooping Black and Not Eating — Why It Happens
Black stool and appetite loss in dogs often signal internal bleeding, digestive disorders, toxin exposure, or organ dysfunction.
Melena (black, tarry poop) usually means there’s bleeding somewhere in the upper gastrointestinal tract. Combined with a loss of appetite, this symptom pairing could stem from ulcers, severe infections, poisoning, or even cancer.
In some cases, certain medications or supplements may also cause black stool, especially if they irritate the stomach lining.
Common Causes of Dog Pooping Black and Not Eating
Gastrointestinal Ulcers
Ulcers in the stomach or small intestine can bleed, causing digested blood to turn the stool black.
These ulcers are often due to long-term NSAID use, kidney disease, or even stress. Affected dogs may seem lethargic, vomit occasionally, or show signs of abdominal pain. They often stop eating due to discomfort.
Left untreated, GI ulcers can worsen, leading to more bleeding, weakness, and dangerous dehydration.
Internal Bleeding
Black stool is a hallmark sign of internal bleeding, often from the upper GI tract or organs like the liver or spleen.
This may be caused by trauma, ruptured tumors, clotting disorders, or advanced infections. Dogs with internal bleeding may appear weak, cold to the touch, or have pale gums. They often refuse food and can deteriorate quickly.
Immediate veterinary care is crucial when this is suspected.
Related: Dog diarrhea and not eating (Causes and what to do)
Toxin Ingestion
Dogs that consume toxins like rat poison, certain human medications, or harmful plants may suffer internal bleeding.
Melena and loss of appetite are two early signs. Owners may also notice vomiting, restlessness, or shaking. Because these toxins work quickly and silently, early intervention is vital.
Even small amounts can be fatal without timely treatment.
Cancer or Tumors
Gastrointestinal cancers, especially in older dogs, can cause internal bleeding and reduce appetite.
Tumors may be located in the stomach, intestines, or surrounding organs. Symptoms develop gradually—black poop, vomiting, weight loss, and reluctance to eat.
Some tumors bleed intermittently, so signs can seem to come and go, making them harder to detect early.
Liver Disease
Advanced liver disease can lead to clotting problems and gastrointestinal bleeding.
Black stool may result from bleeding ulcers caused by liver dysfunction. Dogs with liver problems also exhibit signs like jaundice (yellow gums or eyes), vomiting, and a disinterest in food. Because the liver plays a key role in digestion and toxin filtration, its failure impacts the entire system.
This condition is serious and often progressive without veterinary care.
Infections and Parasites
Severe bacterial or viral infections, like parvovirus or salmonella, and heavy parasitic infestations can cause black stool and appetite loss.
These issues can damage the intestinal lining and cause internal bleeding. Symptoms usually include diarrhea (which may be bloody or black), vomiting, and dehydration. Young puppies and older dogs are especially vulnerable.
Rapid treatment is essential to prevent complications.
What to Do If Your Dog Is Pooping Black and Not Eating
Stay calm and assess your dog’s behavior. Is your dog still drinking water? Are they active or lethargic? These details help determine next steps.
Withhold food for a few hours to let the digestive system rest, but offer small amounts of water frequently. Avoid giving treats, table scraps, or medications unless advised by your vet.
Take a photo of the black stool to show your veterinarian. Keep track of any other symptoms like vomiting, weakness, or shaking. If your dog is on any medications, check the side effects—some can cause GI bleeding.
Avoid giving any over-the-counter remedies at home unless your vet approves. Many human meds (like ibuprofen) are toxic to dogs.
If your dog starts showing other concerning signs or doesn’t improve within 12–24 hours, seek veterinary attention right away.
When to Call or Visit Your Vet
Black stool and appetite loss are rarely benign. Call your vet immediately if you notice:
Black, tar-like stool more than once
Vomiting or signs of abdominal pain
Pale gums or visible weakness
Excessive drooling or trembling
Collapse, disorientation, or signs of internal distress
Don’t wait to see if it resolves. Early intervention can be life-saving, especially in cases of poisoning, bleeding ulcers, or organ failure.
Read more: Dog Pooping Blood and Not Eating or Drinking (Here’s why)
Key Takeaway
If your dog is pooping black and not eating, it’s a sign that something serious could be happening inside.
Monitor their symptoms closely, offer water, and don’t delay in contacting your veterinarian. With quick action, many underlying causes can be treated effectively.
Always trust your instincts—if something feels wrong, your vet is the best ally for your dog’s health.