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Black dog poop: What can poop tell about your dog's health

By Alice Lang Copywriter

Updated on the

When humans are ill, we can shout, scream, cry and complain as much as we want or need to. But our dogs can’t tell us when they’re under the weather - so as gross as it sounds, one thing we can do, to check their health is monitor their poop. Let’s chat about black dog poop, and what it could mean for your dog’s health

You can understand a lot about your dog’s health from their behaviour, appetite, mood... and poop! Yup, the idea of checking up on your dog’s faeces may sound disgusting, but changes can help you detect a number of health conditions or diseases which will probably require a trip to the vet.

And when you think about it, you know your dog’s poop pretty well. You clean it up and pick it up pretty much every day. So if you’ve noticed that it’s suddenly turned a strange shade of black, it can come as a little bit of a shock.

What is ‘normal’ when it comes to dog poop?

“A normal stool for a dog should be firm and dark brown in colour… and the colour of the stool should be fairly consistent from day to day, providing the dog eats a regular diet” explains Dr Dawn. M. Spangler to Dogster. When it comes to dog poop (what a fun subject!), you need to keep 4 main characteristics in mind. These are:

  • Colour
  • Content
  • Consistency
  • Coating

The colour of your dog’s faeces, as Dr Spangler told us, should be a chocolatey brown shade. It’s normal for poo to have minor colour changes linked to diet and hydration, but there shouldn’t be a substantial or prolonged change. You’ll be pretty familiar with what shade your pooch’s poop is normally - so just keep an eye out for any changes which occur for more than a week.

When it comes to content, it’s best to leave it to your vet as it’s hard to see what’s inside without a microscope. In the unlikely event that you do see something strange in their poop, such as worms, head to the vet.

In terms of consistency, a healthy stool should ideally be a ‘log’ shape and firm in consistency - although a runnier stool every once in a while isn’t a concern.

And lastly, if your pooch is healthy, their poop should have no coating whatsoever. If you spot a coating of mucus, it might signal bowel inflammation - so monitor it carefully.

Black dog poop: what it could mean

For the most part, black dog poop is an indication that bleeding has or is occurring in the stomach or small intestines. Understandably, it might seem a little scary - but it can be caused by a variety of conditions - some more serious than others.

“The stool is black because the blood has been digested, causing it to change colour,” Dr Sprangler says. “A few of the more common causes of black dog poop are cancer, foreign bodies, parasites, and viral or bacterial pathogens.”

Tarry appearing, black dog poop can normally be attributed to melena, which is when blood has been digested and makes it way into the small intestine, ending up in a dog’s poop.

This happens because the iron which is present in the blood oxygenates as it passes through a pup’s body, causing it to change colour. It’s important to head to the vet as soon as you notice melena, as it can signify a variety of diseases - which we’ll go through now:

Medication reactions

Has your pooch recently started a new medication? This could be the single cause of black dog poop. Although it’s rare, dogs can have such a severe reaction to a certain medication, that internal bleeding occurs.

Heavy metal poisoning

Dogs can get very sick from ingesting toxic levels of heavy metals such as arsenic and lead. They could pick this up from paint, tiles, plumbing materials, and lead foil, amongst others.

As well as black dog poop, symptoms include vomiting, abdominal pain, running around in circles, seizures, loss of muscle coordination and general strange behavioural changes.

Metabolic diseases

Diseases such as pancreatitis, liver disease and hypothyroidism can cause black dog poop. Dodgy metabolism normally means dodgy poop. Thankfully, metabolic diseases are normally easily detected and treated by a vet.


Has your pooch been involved in a minor accident recently? They may be more injured than you first thought. A black stool can indicate that there’s internal bleeding going on somewhere in a dog’s digestive system.


We get it - no one wants to hear the ‘C’ word when it comes to their pooch. But the one thing to give you peace of mind when it comes to cancer is that the sooner it’s found, the better the chance of recovery - so checking your dog’s poop is vital.

Black dog poop can be a sign of cancer. If cancer is the culprit, you’ll likely have noticed other symptoms such as unintentional weight loss, extreme tiredness and a loss of appetite.

Gastrointestinal ulceration

Ever heard of a stomach ulcer in humans? They’re very common - and they’re a problem for dogs, too. Gastrointestinal ulcerations happen when the gastric acid secretion is out of whack or basically have a breakdown, causing an ulcer to develop.

Your dog may experience black dog poop if they’re suffering from a stomach ulcer. They might also exhibit signs of anaemia, weight loss, loss of appetite, a fever and vomiting (which may also contain blood).

Black dog poop: what to do

If you've noticed black dog poop, it's impossible to understand what's causing it without heading to the vet for a diagnosis. Head there as soon as you can and inform them of your pup's toilet situation.

They'll likely take your pup's temperature, blood pressure and heart rate and ask you a number of questions about any significant behavioural or diet changes. They might then go ahead and carry out a blood count, a faecal examination, X-rays and in severe cases, an endoscopy. Treatment will depend on the diagnosis.

The only thing you can do if you've noticed black dog poop is to head to the vet at the earliest opportunity. Try not to worry too much, as the cause may not be anything too serious. We hope your pooch is back to his normal self very soon!

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