Seeing blood in your dog’s stool can be scary, especially if it has never happened before. Whether your dog is a puppy or has been with you for years, seeing blood in your pooch’s stool is extremely distressing. If this happens, you should take immediate action and bring your dog to the vet.

Understanding the different types of bloody stool (and what may be causing it) is critical in understanding the health of your pup. Once you understand what might be happening, you can take action to help your best buddy feel better again.

Bloody Stool in Dogs: What to Look For

bloody stool in dogsBloody stool can have two distinct characteristics, and knowing the difference will help you – and your vet – identify what may be ailing your dog.

There are two main types of bloody dog stool: hematochezia and melena.

Hematochezia is characterized by its bright red color.1 Bright red stool indicates that your dog may have bleeding in their lower digestive tract or colon. Prior to seeing the blood in your dog’s stool, you may also notice that your dog cries, or whimpers, when trying to go to the bathroom – or that they have diarrhea that has a mucus consistency.

Also, be on the lookout for a bloody stool that is more black and tar-like. If your pooch is passing stool like this, they may have melena. Melena is defined by its dark color and sticky texture. Melena can occur if the dog is digesting or swallowing blood, which usually occurs higher up in the digestive tract.2

What Causes Hematochezia and Melena?

A lot of health issues can lead to hematochezia and melena symptoms in your dog. Parasites, rectal, colon, and extra-intestinal diseases are all common culprits, and each of these problems has its own root cause.

Rectal and anal diseases can lead to a bloody stool in your dog. They are characterized by one, or many, of the following issues: rectal polyps, something lodged in the anus or lower colon, or traumas – such as bite wounds from another animal. While rectal polyps rarely occur in dogs, your veterinarian can feel them during an examination3

If you think you see any of the symptoms of rectal or anal disease, consult your vet as soon as you can.

What Are Some of the Diseases and Conditions I Should Know About?

Now, there are several reasons why your dog may be passing bloody stool. Some of the more common include:

  • Colitis (colon inflammation)
  • Parasites, like hookworms
  • Trauma
  • Toxic substances
  • Inflammatory bowel disease
  • Anal sac infections or impactions
  • Viral or other infections
  • Ulcers
  • Liver disease
  • Reaction to anti-inflammatory medication4
  • Make sure you pay special attention if you notice your dog passing diarrhea or feces with a mucus-like consistency.

There are a few specific intestinal or colon conditions you should be particularly aware of. These include:


Parvovirus is a common disease that can be fatal to dogs if not caught early on. “Parvo” is highly contagious and can be passed through direct contact with another dog, feces, exposed surfaces (such as food bowls, crates, collars, and leashes. And since it can withstand extreme temperatures (both hot and cold) it’s one resilient disease5

Aside from bloody diarrhea or mucus feces, signs your dog may have been exposed to parvo include lethargy and bloating. The best way to find out if your dog has parvo is to consult your vet and have them conduct a fecal test.

The good news is that a vaccination exists for parvo, so if you’re a new puppy parent, be sure to ask your veterinarian about the parvo vaccine.

dog diseases and conditionsHookworms

Blood in the stool, or bloody diarrhea, can be a sign of hookworms. Hookworms are parasites that infect the intestinal tract of your dog, and they are easily transmitted.

Hookworm eggs live in passed fecal matter, and they can infect the nearby environment, which means if your pooch walks on the infected ground, or eats the infected feces, they could become exposed.6

Hookworm larvae can also pass through the skin. From there, the parasites can travel through your dog’s blood and into his lungs. Your dog may then cough up the larvae and swallow them again – where the hookworms will mature in your pup’s small intestine.

Since the mature hookworms then feed by bloodsucking, dogs – especially young puppies – may become anemic quickly. This is a serious health issue that warrants a vet trip as soon as possible. If you think your dog may have hookworms, your vet can run a lab test of a fecal sample to know for sure. Thankfully, for you and your dog, treatments exist to eliminate hookworm infections in dogs.7

Hemorrhagic Gastroenteritis

Hemorrhagic gastroenteritis (HGE) is distinguished by vomiting and large amounts of bloody diarrhea. Though it can affect any dog, it’s more common in small and toy breeds, like French poodles, miniature schnauzers, Yorkshire terriers, Pekingese, and Cavalier King Charles spaniels.

Unfortunately, the exact cause of HGE isn’t really known. But it’s thought that it may be related to such a broad range of things, including stress, anxiety, hyperactivity, ingesting non-food items, changes in diet, toxins, an allergic reaction, bacteria, or an immune disease.8

You should look out for other symptoms of HGE such as a painful abdomen, a decreased appetite, or fatigue. Your dog may need intravenous fluids if they are suffering from HGE, so it’s of the utmost importance that they are seen by a vet immediately.

Treatment and Prevention

Depending on what your vet discovers, treatments may vary. But medications are usually the starting point for conditions that cause bloody stool. Make sure your vet knows what medications your pet is already on, and always monitor a pet for side effects if they’re taking a medication for the first time.

They say that prevention is always better than a cure, so make sure that your dog is living their life in the healthiest way possible. It’s up to you to ensure that your home, your yard, and the places where you take your pup, are safe.

  • Keep your dog’s bowl clean, and refresh the water often.
  • Keep your household garbage secured at all times.
  • Clean up pet poop from your yard.
  • When out and about, keep your pup on a leash to prevent them from eating feces of an unknown animal.
  • Minimize the amount of “human” food your dog eats, and never give your dog anything that’s been in the trash.
  • Keep your dog in optimal health for fighting off nasties with a nutritional diet and make sure they get plenty of exercise.
  • Get to know your dog well, so that any strange behavior may be recognized.
  • If you discover a bloody stool from your pup, take them to your vet immediately to minimize serious outcomes.
  • Take your dog for annual examinations, so that your vet can catch any issues early.

Only the Best for Your Pup

Blood-red and mucusy stool can certainly be alarming, and things like hookworms, HGE, and parvovirus all sound pretty scary. The symptoms, if not treated, are frightening – and can even be fatal. But you and your puppy can both sleep better at night, knowing that there are treatments, preventative care options, and vets who know what to look for – and exactly what to do.

So, do your due diligence. If you notice your pup having bloody stools, talk with your vet. Veterinarians are trained to diagnose a variety of diseases and conditions in your pup – and treatments are available that will have Fido feeling better in no time!

Learn More About Pet Health:
7 Reasons Why Your Dog’s Vomiting White Foam
Mucus In Your Dog’s Stool: What’s Normal, What’s Not?

*Article updated 4/15/2019.