The daily walk with your dog and being a pleasant moment you share with your faithful friend is a perfect opportunity to observe his type of droppings. Your dog’s poop can tell you a lot about his health! This article explains what to do when you discover blood in a dog’s stool.

What is the origin of blood in the stool?

Blood can come from different parts of the digestive tract: the oesophagus, stomach, small intestine, colon and rectum.

The colour of the stool varies according to the origin of the blood:

  • If the blood comes from the upper part of the digestive tract: the stools are blackish (the blood is digested), and we speak of melena
  • If the blood comes from the terminal portion of the small intestine, the colon or the rectum: the stools are red, and we speak of hematochezia.


If you observe blood in your dog’s stool, you should go to the veterinarian immediately. Blood can come from any part of your dog’s digestive tract. Depending on its origin, the blood in the dog’s stool has different characteristics. The blood can be fresh – red or digested – black in colour -. It is essential to pay attention to these characteristics because your veterinarian will ask you about them. 


This is undoubtedly the most disturbing and impressive case. Red blood – hematochezia – indicates that the bleeding is in the last part of your dog’s intestine. It probably comes from the colon, rectum or anal glands. Here are the possible causes: 

  • Inflammation of the colon, or colitis: It is relatively common and usually appears due to a sudden change in food or after an episode of stress. Other possible causes are food intolerances or allergies. The dog’s droppings appear with drops of blood and sometimes also mucus. 
  • Constipation: A diet that does not provide the correct amount of fibre can cause lesions in the rectum due to the effort the dog makes to defecate if the stools are very dry. 
  • Anal Gland Diseases: On either side of the anus, your dog has glands containing a smelly fluid from the stool. Dogs communicate with these secrets – that’s why they sniff each other’s anal area when they meet – and mark their territory. If the glands are affected by a specific lesion and have wounds or fistulas, it can lead to blood in the dog’s stool. 
  • Intestinal Parasites: Another cause of bloody stools has intruders in your dog’s intestines. Parasites adhere to the intestinal mucosa, causing bleeding wounds. 
  • Hemorrhagic gastroenteritis: Any breed can suffer from it, but it is more common in small or miniature breeds. The cause is unclear, but the animal begins to expel a large quantity of fresh blood, which may or may not be accompanied by diarrhoea. You should go to the vet immediately if this happens to your dog.
  • Polyp: They are more common in older dogs – usually males – they are fragile tissues formed in the intestine, bleeding easily. 
  • Parvovirus: This disease of viral origin mainly affects unvaccinated puppies. Some symptoms are diarrhoea with fresh blood, vomiting, lack of appetite and weakness. 
  • Poisoning: If your dog has blood in the stool, it may be because he has been poisoned. Rat poison, for example, prevents the blood from clotting and causes bleeding in different body parts. If you suspect your dog has accidentally eaten poison, go to your veterinarian urgently. 

Causes of Blood in Dog Stool

Often to help your veterinarian diagnose, you will have to give the appearance of blood in the dog’s stool, which is not always easy to describe.

  • Diarrhoea with blood appearing at the end of the stool in tiny quantities. This blood in the dog’s stool often marks irritation of the distal digestive tract (rectory bleeding) after diarrhoea lasting several days or has occurred many times.
  • Presence of mucus or blood-coloured phlegm
  • Blood in kind, liquid, in large quantities with or blood clots. This symptom is an emergency. There is an actual haemorrhage.
  • Stools tinged with red blood.
  • Faeces contain digested blood: they are black; we speak of melena. This symptom often signs the presence of an ulcer in the stomach. And also represents, depending on the cause of the appearance of the ulcer, an emergency character. Indeed, ulcers can be excruciating.

Details on the appearance of the dog’s diarrhoea, if any, and on the other associated symptoms, in particular, the general condition (fatigue, appetite, the temperature of the dog, etc.) and vomiting (signs of gastritis in the dog) allow to determine the digestive origin of bleeding.

You should also determine if the dog has not ingested toxic products such as rat poison (or rat poison), anticoagulants or anti-inflammatory tablets that cause bleeding or stomach ulcers (see the article on the poisoned dog). The presence of a foreign body (such as a nail or broken bones) can also cause the digestive lining to bleed.

The dog’s history can also help in the diagnosis, especially for puppies that have not received vaccines for dogs against parvovirus (which causes hemorrhagic gastroenteritis) or adopted from breeding or kennels which may have giardiasis. (parasitic disease giving mucous stools with sometimes blood) or larvae of other worms.

Heatstroke or too sudden dietary changes can also sometimes trigger violent haemorrhagic diarrhoea.

Finally, the presence of tumours or polyps can also be manifested by blood in the stool.


Black, digested blood – melena – looks like tar and smells very bad. This indicates that the blood in the dog’s stool is due to some problem in the upper parts of the digestive tract. Here are some reasons:

  • Bleeding: Any bleeding from the oesophagus, stomach, nose, or mouth causes your dog to ingest the blood, digest it, and finally expel it with the stool. The causes of these haemorrhages vary. It is possible that your dog ate something that caused injury, such as a sharp bone.
  • High dose of anti-inflammatories: Medications, such as ibuprofen, can cause ulcers in the stomach and, in the most severe cases, perforations in the intestine.

Know that just because you notice your dog’s stools are black doesn’t necessarily mean there’s something wrong. Certain medications, such as iron sulfate, or foods such as liver, can cause black-coloured stools

What to do if you find blood in your dog’s stool?

If you think he has heat stroke, do not hesitate to take his temperature and follow the advice in the article on dog temperature. Taking your temperature can also point to an infectious disease, such as parvovirus if it is increased.


Either way, take your dog to your veterinarian so he can assess the severity of the bleeding. After an exact statement of the history of your dog and his illness and a complete clinical examination, he will be able to carry out additional examinations if he deems it necessary. On clinical examination, it may show abdominal pain or bleed from other parts of the body. With a digital rectal examination, he will be able to check that there is no anomaly of the colon or the anal glands, which would cause blood in the dog’s stools.

A blood test will check if no organ is affected and if there are still enough red blood cells in the blood and possibly show anaemia (lower number of red blood cells in the blood). He can have a stool analysis done and do rapid tests to diagnose parvovirus if they are positive. He may do an abdominal ultrasound or an intestinal endoscopy. He may also do coagulation tests if he suspects a clotting problem in your dog.

In some instances, and in particular, in the case of acute hemorrhagic gastroenteritis, the dog will be hospitalized to be rehydrated by infusion. Diarrhoea and vomiting, by increasing water loss, dehydrates animals very quickly. In addition, while being hospitalized, your dog will be able to receive his treatments (antibiotics, vitamins, painkillers or anti-emetics) by injection.


Your veterinarian will likely want to run your dog through various tests to determine what is causing the blood in the stool. If you want to make it a little easier for him, you can bring him a stool sample. Based on the information obtained from the examinations, your veterinarian will make a diagnosis and offer you the appropriate treatment depending on the pathology.

Treatment for diarrhoea (anti-spasmodic, antibiotics and digestive dressing) will be implemented for animals that do not need to be hospitalized. To this, we can add a hyper-digestible diet to avoid maintaining diarrhoea.

If giardiasis has been detected, your dog must receive a special anti-parasitic (wormer). The treatment can be long, and your veterinarian may have to repeat the test several times and redo the stool analysis several times to ensure that your dog is cured and cleared of his giardiasis.

There is a specific antidote for bleeding caused by ingesting rat poison. However, it is necessary to treat as quickly as possible and preferably before the appearance of symptoms. If you think your dog has eaten rat poison, you should put him under treatment without delay.


Some of the causes or diseases described are difficult to prevent. However, if you want your dog to have good gastrointestinal health, you can avoid blood in the stool in cases where prevention is possible. Here are our tips:

  • Be up to date with your dog’s vaccinations: Especially in the case of puppies. If you haven’t vaccinated your puppy, avoid taking him to dirty places where he can catch parvovirus. 
  • Deworm it: It is better to do it every three months.
  • Offer him probiotics: You will be able to strengthen the intestinal flora of your dog. This will dramatically improve your dog’s gut health, which will help him deal with possible colitis.
  • Do not self-medicate your dog. This is forbidden, and it is important not to administer anti-inflammatories without veterinary supervision. 
  • Offer him a special diet: If your dog is often constipated, you can offer him a special diet. ADVANCE Light is indicated for both puppies and adult dogs. It is an elaborate food with a high fibre content, which contributes to better functioning of the digestive tract. Plus, it’s low in fat and rich in vitamins and minerals. If your dog has gastroenteritis, you can offer him the ADVANCE Gastroenteric diet, which is made with highly digestible ingredients, a low-fat level and a high proportion of sodium to reduce gastrointestinal upset. 

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