Black Dog Poo: Causes, Red Flags, and When to Call the Vet (Vet-Approved Guide)
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Black poo in dogs usually comes down to one of two things: digested blood from somewhere in the gut, or something your dog ate.
The first is called melena and can be serious. The second is just food doing what food does — nothing to worry about.
The problem is they can look the same. And melena can happen even when a dog seems completely fine. Knowing which is which matters.
If you've just noticed dark or black stool and you're not sure what to do, that's exactly what this guide is for. I'll cover what causes black poo in dogs, how to tell real melena from a dietary stool change, the "acting normal" question, and when to call your vet.
- Black poo in dogs is called melena — it means blood has been digested in the stomach or small intestine before passing through
- Melena looks different from normal dark-brown stool: it is tarry, sticky, and has a distinctively strong smell
- Some foods (organ meat, blueberries, bone) and medications (iron supplements, activated charcoal) can darken stools without any bleeding
- A dog can have melena and still behave normally — normal behaviour does not rule out a serious cause
- Always call your vet on the same day if you notice black tarry stool; go immediately if vomiting, lethargy, or pale gums are also present
What Is Black Poo in Dogs?
Black, tarry stool in dogs is called melena — it means blood has been digested in the upper gut (stomach or small intestine) before passing through.
Healthy poo ranges from light to dark brown depending on what your dog eats. When bleeding happens in the stomach or upper small intestine, that blood gets broken down as it moves through the gut. By the time it comes out, it has turned black and taken on a sticky, tar-like texture. It also tends to have a noticeably strong, different smell.
How to tell it apart from just "very dark brown" stool:
- Melena is genuinely black, not a deeper shade of brown
- It has a sticky, tarry feel — it may cling to grass or surfaces differently to normal poo
- The smell is stronger and different in character
- It looks black from the moment it is passed, not after drying out
What About Dark-Coloured Foods?
Some foods and supplements can make stools much darker without any bleeding involved. The most common are organ meats (liver, kidney, heart), raw-fed diets high in blood content, blueberries, beetroot, and activated charcoal. Iron supplements can also turn stools very dark, sometimes almost black.
The difference: dietary dark stool is firm and formed, without the tarry texture or strong smell of melena. If your dog has eaten a lot of liver recently and the stool is otherwise normal in consistency and smell, food is probably the reason. But if you are in any doubt, call your vet.
For a complete guide to what your dog's poo is telling you, see our dog poo colour chart.
When to See a Vet
Call your vet the same day you notice black tarry stool — go immediately if your dog is also vomiting, lethargic, or has pale gums.
Go immediately (treat as an emergency):
- Black tarry stool plus vomiting
- Black tarry stool plus lethargy or weakness
- Pale or white gums
- Rapid heart rate, laboured breathing, or signs of collapse
- Known or suspected ingestion of a toxin or foreign object
Call your vet today (same-day):
- Black tarry stool with no other symptoms — including if your dog seems completely normal
- Black stool that persists for more than one bowel movement
- Your dog is on NSAIDs (Rimadyl, Carprieve, Metacam) and their stool colour has changed
- You're not certain whether the stool is black-tarry or just very dark brown
Don't wait to see if it resolves on its own. Even with no other symptoms, black stool can mean significant internal bleeding. One phone call can make a real difference to what happens next.
What Causes Black Poo in Dogs?
The most serious cause of black stool is bleeding somewhere in the upper gut — but food and medications can also make stools darker without any bleeding involved.
Gastric Ulcers and GI Bleeding
Gastric ulcers form when the stomach lining breaks down. A bleeding ulcer is one of the most common causes of melena. Ulcers can develop from chronic inflammation, stress, certain diseases (including some cancers), or long-term use of certain medications.
Bleeding can also come from tumours, swallowed foreign objects, clotting disorders, or inflammatory bowel disease. In each case, blood enters the upper gut and is digested before passing out.
Other signs that can come with a GI bleed include reduced appetite, vomiting (sometimes with blood or dark material), and pain when you touch the belly. But not every dog shows these. Some dogs bleed slowly and seem completely fine — still eating, still playing — until the point where they can no longer compensate.
Iron supplements can also turn stools much darker, sometimes almost black. That's a dietary change, not a bleed — but worth knowing if your dog is on iron.
NSAID and Medication Use
NSAIDs — pain relief medications — are one of the most common causes of stomach ulcers in dogs. They're widely used for arthritis, post-surgical pain, and joint conditions. Common Australian brands include Rimadyl and Carprieve (both carprofen) and Metacam (meloxicam).
NSAIDs reduce inflammation by blocking certain enzymes — but those same enzymes also protect the stomach lining. The bleeding can start invisibly, causing mild anaemia before any stool changes appear. In more severe cases it leads to vomiting and black stool.
The longer your dog takes NSAIDs — especially without a stomach-protecting medication alongside — the higher the risk of developing an ulcer. If your dog is on a long-term NSAID and their stool turns black, call your vet that day, regardless of how well they seem.
Hookworms and Intestinal Parasites
Hookworms attach to the gut wall and feed on blood. A heavy infestation can cause enough blood loss to produce black, tarry stools — this is most common in puppies or dogs that are overdue for worming.
Whipworms can also cause bloody stools, though they tend to produce red or pink stool (from the lower bowel) rather than the black tarry kind.
Keeping up with regular worming is the main way to prevent this. Browse our vet-recommended dog worming treatments if you're overdue.
Toxic Ingestion
Some toxins — rat bait (the kind that stops blood from clotting), heavy metals, and human pain medications like aspirin and ibuprofen — can cause internal bleeding and black stool. Aspirin and ibuprofen are toxic to dogs even at low doses and should never be given at home.
If there's any chance your dog has swallowed something toxic, don't wait for symptoms. This is an emergency — act now.
My Dog Has Black Poo But Is Acting Normal
A dog that's behaving normally can still have a serious problem — significant bleeding in the stomach can happen well before any obvious symptoms appear.
This is one of the most common misunderstandings around this symptom. Dogs are naturally stoic. Early or slow bleeding may not yet be causing pain or obvious weakness. Your dog eats, walks, plays, and seems fine — while blood is being lost internally.
Bleeding can start slowly. The body quietly adjusts — still eating, still active — until enough blood has been lost that symptoms become impossible to hide.
If the black stool comes with vomiting, lethargy, a drop in appetite, or pale gums, that's a clear escalation. But the absence of those signs doesn't mean you're in the clear. A dog with black tarry stool who seems completely normal still needs a same-day vet call.
When you do call — and I'd encourage you to call that day — the more detail you can give, the better. How many times? How long has it been happening? Is there a strong smell? Does the texture look sticky or formed? And take a photo.
"One thing that really helps when you call the clinic — take a photo before you clean it up. Colour, texture, and whether it looks tarry or just dark: that information changes what I can advise over the phone. A photo takes five seconds and means I'm not working from 'it looked quite black, I think."
Dr Jack Ayerbe OAM
Veterinarian & Vets Love Pets Partner
Can Dog Poo Turn Black When It Dries?
Normal dog poo does not turn black as it dries — if it came out black, it was black from the start.
I get asked this one a lot, and I understand why — most pet parents want to hear it's just the light, or the heat, not something to worry about.
Here is what actually happens when poo dries out: it loses moisture, gets firmer, and may look slightly lighter or more faded on the surface. If the colour changes at all, it gets lighter — not darker.
If you noticed it was black when it was passed, trust that. Don't wait to see if it "lightens up." Call your vet the same day.
One genuine exception: very dark brown stool in poor lighting can look black. If you're unsure, texture and smell are your best checks — melena is sticky and tar-like, and the smell is noticeably stronger than normal poo.
How to Treat Black Poo in Dogs
Treatment depends on the cause — and finding the cause comes first. Your vet needs to examine your dog before anything else.
What to Expect at the Vet
Your vet will start with a physical examination and some questions: what your dog has been eating, any medications they're on, how long the stool change has been happening, and whether anything else has changed recently.
From there, likely next steps include blood tests to check for anaemia and clotting issues, a stool sample to rule out parasites, and possibly an ultrasound or X-ray if something more serious is suspected. If significant bleeding is likely, an endoscopy may be recommended to find the source.
In Australia, an initial consult is typically $200–$350 AUD. Endoscopy, if needed, is generally $1,500–$3,000 AUD depending on the clinic and location.
Medical Treatment
Treatment depends on what's causing the bleed:
- Gastric ulcers: medication to reduce stomach acid (such as omeprazole), stomach-protecting medication (sucralfate), and antibiotics if a bacterial cause is found
- NSAID-related stomach damage: stop the NSAID under your vet's guidance; add stomach protection; switch to a pain relief option that's gentler on the gut
- Hookworms or parasites: a prescription worming treatment, then a follow-up stool test to confirm clearance
- Significant internal bleeding: may need hospitalisation, IV fluids, a blood transfusion, or surgery depending on the cause and severity
Don't try to manage this at home before a diagnosis. You can offer bland food if your dog is eating and your vet has said that's okay — but treatment needs a confirmed cause first.
Supporting Recovery at Home
Once your vet has given the all-clear, a bland diet of plain cooked chicken and rice helps the gut settle. Avoid rich foods, raw meat, and bones until it has had time to heal.
Probiotics can help rebuild healthy gut bacteria and support recovery after illness or antibiotics. Browse our vet-recommended digestive health supplements, including Pro-Kolin and Synbiotic D-C.
Pro-Kolin Probiotic Paste for Dogs and Cats
A paste with probiotics and gut-soothing ingredients designed to firm stools and support recovery during and after a GI illness.
Why our vets recommend it: specifically formulated for short-term gut recovery, with 235 customer reviews and a 5.0-star average.
Synbiotic D-C Probiotic and Prebiotic Capsules
A combined probiotic and prebiotic supplement for dogs and cats, designed to restore healthy gut bacteria after illness or antibiotics.
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Browse the Protexin Veterinary brand.
Prevention and Long-Term Management
Most causes of melena are preventable with regular worming, careful use of pain medication, and routine vet checks.
Keep worming up to date. Hookworms are largely preventable with a regular worming schedule. If you've recently adopted a dog or aren't sure when they were last wormed, speak to your vet. Browse our dog worming treatments for vet-recommended options, and see our year-round parasite prevention guide for AU-specific advice.
Be careful with pain relief. Always use the lowest effective dose, under your vet's guidance, for as short a time as possible. Never give your dog human anti-inflammatories — aspirin and ibuprofen are toxic to dogs. If your dog is on long-term pain relief for something like arthritis, ask your vet whether a stomach-protecting medication should be given alongside it.
Know your dog's normal. If you feed a raw or organ-heavy diet, your dog's stools may naturally run darker. Knowing what normal looks like for your dog means you'll notice a genuine change much sooner.
Support gut health long-term. Dogs with a sensitive stomach, or who've recently recovered from a gut illness, may benefit from ongoing probiotic support. Explore our dog probiotic range or read more about supporting your senior dog's gut health.
Black Dog Poo FAQs
Why is my dog's poo black?
Black poo in dogs is usually melena — blood that has been digested in the stomach or small intestine before passing through. It can also come from certain foods (organ meat, blueberries) or supplements (iron, activated charcoal). If the stool is black, sticky, and unusually strong-smelling, call your vet the same day.
What does tarry black stool look and smell like in dogs?
Melena is sticky and tar-like — it clings to surfaces and doesn't form the way normal stool does. The smell is noticeably stronger and different to regular poo. Dark-brown dietary stool, by contrast, is firm and formed, without the tarry texture or the intensified smell.
Can worms cause black stools in dogs?
Yes. Hookworms feed on blood from the gut wall; a heavy infestation can cause enough blood loss to produce black tarry stool. This is most common in puppies or dogs overdue for worming. Your vet can confirm with a stool test and treat with a prescription worming medication.
Can pancreatitis cause black stools in dogs?
Pancreatitis doesn't usually cause melena directly, but severe cases can lead to gut inflammation or complications that produce dark stool. If your dog has pancreatitis and develops black stool alongside vomiting or belly pain, call your vet promptly — it may signal a complication that needs attention.
What can I give my dog for black stool at home?
Nothing — not before a vet has looked at them. Black stool can mean internal bleeding, and giving food, supplements, or medication before you know the cause can delay the right treatment. Call your vet the same day. If your dog is eating and your vet has cleared home management, plain cooked chicken and rice is a safe option. Probiotic support like Pro-Kolin is useful during recovery, once your vet has said it's appropriate.
What to Do Next
Black poo in dogs is worth taking seriously — but most causes are very treatable when caught early. Ulcers, hookworms, medication side effects: all of these respond well once a diagnosis is made. The key is calling your vet rather than waiting for other symptoms to appear.
If you noticed black tarry stool today, that call is the right first step. And if you're thinking ahead, keeping up with worming and being mindful of long-term pain relief are the most effective things you can do. Our gut health and digestive supplement range is a good starting point for dogs in recovery or with an ongoing sensitive stomach.
Veterinarian & Vets Love Pets Partner
BVSc
Dr Jack Ayerbe OAM is a distinguished Geelong veterinarian with over 50 years of experience, the founder of Newtown Veterinary Practice, and a dedicated advocate for animal welfare and ethics.
More articles from Dr Jack AyerbeReferences
- MSD Veterinary Manual. Gastrointestinal Ulcers in Small Animals. Accessed May 2026.
- MSD Veterinary Manual. Nonsteroidal Anti-inflammatory Drugs in Animals. Accessed May 2026.
- MSD Veterinary Manual. Gastrointestinal Parasites of Dogs. Accessed May 2026.
- Habing G, et al. Plasma urea:creatinine ratio as a biomarker of gastrointestinal bleeding in dogs with anaemia. Vet Rec Open, 2023.
- RSPCA Australia. Intestinal Worms in Dogs.
