Black, sticky, tar-like stool is digested blood — a sign of upper GI bleeding that warrants a same-day vet visit.
Most stool changes can be monitored for a day or two. Black, tar-like stool isn't one of them. Called melena in veterinary terminology, it represents digested blood from somewhere in the upper GI tract — and it's almost always a same-day vet call.
Most pet wellness is over-formulated and under-supported. Here's what melena indicates, common causes, and what the diagnostic process looks like.
What melena actually is
Melena is dark, tarry, often sticky stool — sometimes described as looking like used coffee grounds or roofing tar.
The dark color comes from blood that has been digested through the GI tract. Hemoglobin oxidizes as it passes through.
Source is typically the upper GI tract: stomach, small intestine, sometimes esophagus.
Why it's different from fresh blood
Fresh red blood in or around stool comes from the lower GI tract — colon, rectum, anal area.
Digested (black) blood comes from upper GI. The location matters for diagnosis.
Both are worth a vet conversation, but melena is generally more urgent.
Common causes of upper GI bleeding
Gastric ulcers — often NSAID-induced, sometimes stress-related, sometimes due to other underlying disease.
Severe gastritis or enteritis.
Foreign body causing GI lining damage.
Tumors of the upper GI tract.
Coagulation disorders — bleeding problems from any cause.
Toxin exposure — certain rodenticides cause severe bleeding.
Hookworm or other heavy parasite burden.
Each requires specific diagnostic workup.
Why same-day vet care matters
Blood loss can be significant even when stool changes are the first visible sign.
Severe ulcers can perforate, causing peritonitis — life-threatening emergency.
Underlying causes (toxin exposure, coagulation disorders) can deteriorate rapidly.
Don't wait to see if it persists. Don't try home remedies. Call your vet today.
Diagnostic workup
Physical exam including assessment of hydration and shock signs.
Bloodwork — CBC to assess for anemia, chemistry panel, coagulation panel.
Sometimes imaging (radiographs, ultrasound).
In stable patients, endoscopy may be performed to directly visualize ulcers or other lesions.
Toxin screening if exposure is suspected.
Treatment depends on cause
NSAID-induced ulcers — discontinue NSAIDs, acid suppression therapy (omeprazole, famotidine), gastric protectants (sucralfate).
Severe bleeding — fluid therapy, possible blood transfusion, hospitalization.
Toxin-related — specific antidotes if available, supportive care.
Underlying disease — treat the specific condition.
Your vet will direct the appropriate approach based on findings.
Recovery considerations
Most dogs with appropriately treated ulcers recover well over 2-6 weeks.
Dietary modifications during healing — bland diet initially, gradual return to normal.
Acid suppression often continued for several weeks.
Follow-up exams and possibly repeat endoscopy in severe cases.
Preventing recurrence
If NSAID-related, discuss alternatives with your vet for ongoing pain management.
If stress-related, address the underlying stressors.
If parasites were the cause, comprehensive parasite control going forward.
Always discuss medications, supplements, and dietary choices with your vet — many factors influence GI bleeding risk.
What melena isn't
Dark stool from certain foods (some commercial diets, certain treats) — usually distinguishable but worth your vet's input.
Stool that's just been outside in dirt or mud — appearance can be confusing.
Some medications (Pepto-Bismol containing bismuth) darken stool. Tell your vet what your dog has been given.
When in doubt, photograph and bring the sample to the vet.
Common questions about melena
How quickly should I act? Same day, ideally. Don't wait.
Can I treat this at home? No — diagnosis is essential. Causes range from manageable to life-threatening.
Will my dog be okay? Depends on cause and how quickly treatment starts. Prompt care improves outcomes substantially.
Can I prevent melena? Some causes (NSAID-related, parasite-related) are preventable with appropriate management. Others (tumors, idiopathic ulcers) are less predictable.
What to bring to the vet
A sample of the stool if possible (in a clean container).
Complete list of medications and supplements your dog is on.
Any recent diet changes.
Any potential toxin exposures (rodenticide use in or around your home, ornamental plants, etc.).
Timeline of when symptoms started and any other concurrent symptoms.
Where our formulas fit
Once your dog has recovered from a melena episode and your vet has cleared you to return to normal feeding, a daily soluble fiber input can support steady stool quality during the ongoing recovery period. Soluble fiber is the workhorse for post-treatment GI recovery under vet supervision, and concentrated pumpkin is one of the cleanest sources. Firm Up! is just that — dehydrated pumpkin and pumpkin seed, no flavorings, no binders.
Related reading
The bottom line
Most senior dogs whose owners describe them as 'doing surprisingly well' aren't lucky. They're the beneficiaries of years of small, boring decisions made early. We try to make a few of those decisions easier.