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Written by Vet Evidence Based

Dog Threw Up Blood – 15 Possible Reasons Behind It Explained

Margarita Boyd
Written by: Dr. Margarita Boyd, BVSc MRCVS
Stomach problems in dogs are never fun. However, it doesn't mean that you shouldn't address it. Moreover, if you see your dog throwing up blood, you should react. Read on to explore different reasons behind vomiting blood and learn how you can help your dog.

It can be quite frightening to see your dog throw up some blood, and obviously make you worry about what might have caused it. Hematemesis is the proper medical term used to describe vomiting blood, and there can be lots of possible causes behind it. Common reasons include irritation to the oesophagus, parvovirus infection if your dog ate a foreign object, a bacterial infection in his stomach or due to internal trauma following an accident. Some underlying reasons are emergencies, others are less worrisome, so let’s find out more about what to do if your dog vomits blood so you can be fully prepared.

Why Is My Dog Vomiting Blood?

Vomiting in dogs is often caused by dietary indiscretion, which pretty much means that some dogs will eat anything out of curiosity, poor judgment and sometimes hunger. This includes trash, causing them to feel sick and vomit. Usually, it is nothing to worry about, and the dog recovers uneventfully and quickly at home. However, vomiting can sometimes be a sign of a more serious underlying condition, especially if there is blood in the vomit.

In this article, we will take a look at the signs and causes of vomiting blood in dogs, as well as how it is diagnosed. We will also take you through, step-by-step what you should do if your dog throws up blood. When your dog vomits blood, it is always a good idea to get an appointment with your veterinarian as soon as possible, so they can start ruling out the underlying causes and treating your dog’s problem.

Clinical Signs

Hopefully, you aren’t too queasy, as we will be talking a lot about blood in this article! Like we mentioned above, vomiting blood can be caused by a variety of problems and diseases.

Common clinical signs which might be associated with a dog vomiting blood include:

Reduced appetite
• Tummy pain
• Vomiting food/ water /bile (green/yellow)
• Blackish feces (melena)
• Weakness
• Pale mucous membranes (pale gums)
• Collapse

What Does The Blood Look Like?

You might not know that the blood that a dog vomits up can appear in different forms and even colors! For example, it might be fresh blood that looks bright red or blood clots which are red clumps. Digested blood is darker in color and looks more like coffee grounds. The color and appearance of the blood can help to figure out which part of the digestive tract it came from.

The blood can appear in spots or streaks mixed with vomited food or froth, or when there is a lot present a pool of blood. The fresh red blood that has quite a lot of mucus present, is most likely from the mouth, esophagus (the tube that connects the mouth to the stomach), or stomach. It may be an indication that one of these areas is ulcerated and actively bleeding. Very dark red blood usually means that the blood has been partially digested in the stomach. Blood that is nearly black and looks similar to coffee grounds, usually means that it is older and has been digested. (1)

The appearance of the blood in the vomit can help you (and your vet) to figure out where the problem has started. It is a good idea to note the appearance of the blood, take a photo and take a sample to your vet if possible.

What Can Cause Your Dog To Throw Up Blood?

Some of the underlying reasons for your dog throwing up blood are less worrisome, such as a cut in his mouth from chewing a bone or a lose tooth. However, blood in the vomit might also be a sign of other more severe conditions such as an internal trauma, stomach ulcer, a foreign object, internal bleeding, parvovirus infection, cancer or a problem with the dog’s blood clotting process. Let’s take a look at some of the causes in a little more detail.

1. Chewing Bones

Any sharp object that your dog chews has the possibility to cause trauma and bleeding in his mouth or oesophagus (the tube which carries the food from the mouth to the stomach). The most common object that causes this problem is bones.

Lots of owners give their dog bones, without knowing the dangers that they can cause, such as obstructions or trauma. Bones can easily break or splinter into sharp bits when the dog chews them. These sharp edges can scratch, tear or puncture the soft tissues in the mouth or further down the gastrointestinal tract. This can cause inflammation and bleeding.

The dog starts to feel sore and nauseous which leads to vomiting the blood (and sometimes the shards of bone get vomited too, which can do further damage when they are vomited back up again). If a sharp piece of bone punctures a hole in the gastrointestinal tract it could lead to a very serious condition called peritonitis, which is infection and inflammation of the peritoneum lining of the abdomen.

2. Tooth Infection

An infected or lose tooth will often bleed a little, as the gums will be sore and sensitive. The tooth pain may cause the dog to have a decreased appetite, dribble (with some blood) or even vomit too. Although a tooth problem usually only causes a little bit of blood to be present in the dog’s vomit or saliva.

3. Eating A Foreign Object

Lots of dogs are guilty of loving to play with things they shouldn’t, such as socks, batteries kid’s toys and coins, or whatever they happen to find in the home.

Puppies are more likely to try to eat these objects, but some older dogs never grow out of the habit of wanting to gulp down something they shouldn’t. Foreign objects can cause irritation and bleeding of the oesophagus, stomach, and intestines if they pass that far. They can also cause an intestinal obstruction.

4. Dietary Indiscretion

One of the most common reasons for vomiting in dogs is due to dietary indiscretion. This is a fancy way of saying, that lots of dogs will try to eat something they shouldn’t (usually from the garbage)which then makes them sick.

It is similar to a dog eating a foreign object, but in this case, the cause of vomiting blood is more food-based. This usually causes acute gastritis or sudden inflammation of the stomach. Common causes include spoiled or rotten food, cat litter, plants, household cleaning products, human food leftovers. It usually starts with the dog being lethargic, vomiting and having a decreased appetite (anorexia).

Further signs may include blood in the vomit or feces, dehydration and tummy pain. It is often self-limiting, with the dog recovering within 24 hours. However, sometimes veterinary treatment is required especially if dehydration is present, or a lot of hazardous material has been eaten.

5. Parvovirus Infection

Canine Parvovirus (CPV) is a very contagious viral infection of dogs. It mainly affects puppies less than 6 months of age, and every vet dreads it, as it is often fatal. This severe infection usually causes vomiting, often bloody vomit, lethargy, fever, decreased appetite, and bloody diarrhea. Unfortunately, there is no cure for this deadly viral infection, and the dog needs intensive supportive treatment as soon as possible to try to recover from this disease.

6. Rat Poison Ingestion

A common type of rat poison which if ingested by dogs can cause vomiting blood is the anticoagulant group of rodenticides. However, there are lots of different types of rat and mice poisons available, which contain different active ingredients and come in different forms (pellets, blocks, powder or liquids) and colors (often blue, green or pink). The effects of the rat poison on the dog which eats it depends on the active ingredient and how much the dog has eaten.

Anticoagulant rat poison may include the following ingredients: warfarin, brodifacoum, bromadiolone, chlorophacinone, coumatetralyl or diphacinone. These kill pests by preventing the synthesis of vitamin K, an essential part of the normal blood clotting process. This leads to spontaneous and uncontrolled bleeding. Signs may not appear until 5-7 days after the dog has eaten the poison.

Clinical signs may include dullness, reluctance to exercise, coughing or vomiting blood, bruising on the skin, pale gums and eventually collapse and death.

7. Hookworms

Hookworms are officially known as Ancylostoma caninum, is a common type of worm which lives in a dog’s intestines. These small worms attach to the lining of the intestines, causing damage and suck the dog’s blood. Adult dogs can get infected from sniffing or licking infected dog poop or soil, and puppies can become infected as the immature worms pass from their mum’s milk. A high number of these parasites can cause a dog to vomit blood, have bloody diarrhea, weight loss and weakness.

8. Blood Clotting Disorders

There are a lot of different blood clotting disorders that can affect dogs, too many to mention them all here. Two of the most common types, which may cause your dog to vomit blood as one of the possible clinical signs, include:

Thrombocytopenia is a condition where there is a reduced level of platelets in the blood. Platelets are necessary for the blood to clot to stop bleeding. Thrombocytopenia may be present at birth (congenital) or develop later in the dog’s life. If it develops later in the dog’s life it has been linked to certain drugs, cancer, vaccinations or immune system disease.

Von Willebrand disease is caused by a deficiency of a certain protein (vWF) needed for platelets to bind together in the normal blood clotting process. This can lead to excessive and uncontrolled bleeding following an injury or surgery. Some breeds of dogs are predisposed including German Shepherds and Dobermans.

9.Stomach Ulcer

A stomach ulcer is a sore, deep, painful area on the inner lining of the stomach. They are difficult to heal, as the stomach is full of acid to help digest food, which can constantly irritate the sensitive ulcer. A canine stomach ulcer can cause regular vomiting, often with blood, as well as decreased appetite and signs of tummy pain.

The dog vomit often looks like coffee grounds, as the ulcer is actively bleeding but the blood has been digested. Canine ulcers are often caused by medications such as NSAID painkillers, steroids or aspirin, but may also be caused by mast cell tumors or liver disease.

10. Antifreeze Ingestion

Antifreeze is the liquid you might spray on your car windshield to de-ice it during winter. This clear fluid is extremely poisonous but is very sweet smelling which entices cats and dogs to want to eat it. Over 72 hours the dog may vomit, have internal bleeding then eventually develop kidney failure. It is a deadly toxin, that needs vet treatment as soon as possible. (2)

11. Haemorrhagic Gastroenteritis (HGE)

HGE is a sudden onset of severe vomiting (often with blood) and bright red bloody diarrhea. It most commonly affects small or toy breed dogs. The underlying cause is still unknown, but it has been linked to food allergies, toxin ingestion, stress, and pancreatitis.

12. Cancer

Bloody vomit may also be a sign of certain cancers in dogs, especially stomach or oesophageal cancers. A dog with lung cancer may also have bloody vomit, as the blood may be coughed up, then swallowed before vomiting. These cancers are much more likely to affect older dogs.

13. Road Traffic Accident

If a dog suffers a big trauma such as being involved in a road traffic accident, it usually causes internal injuries or internal bleeding. As well as possible injuries to the bones, a big trauma may cause clinical signs such as tummy pain, vomiting (with blood) and shock (pale gums, fast heart rate, collapse).

14. Bacterial Infection

Another possible reason for a dog to vomit blood includes a bacterial infection in the gastrointestinal tract. Commonly known as food poisoning in humans, the same bacteria can cause serious bacterial infections in dogs. The most common bacteria to cause tummy problems to include salmonella, E. coli, Campylobacter and Clostridia bacteria. The dog would usually have a decreased appetite, lethargy and diarrhea too.

15. Chronic Gastritis

Long term stomach inflammation also known as chronic gastritis may also cause a dog to throw up blood. Usually, it would start with intermittent vomiting, with small streaks of blood. If the vomiting continues this leads to further damage to the stomach lining and therefore more blood in the vomit over time.

The inflammation and irritation of the stomach lining can be caused by many different conditions including: autoimmune diseases, metabolic or endocrine diseases (Addison’s disease, diabetes), chronic stress, hyper-acidic syndromes, food allergies, inflammatory bowel disease (IBD), neurological disease or kidney failure.

Other Health Conditions

Unfortunately, the possible causes of a dog vomiting blood is a very long list of conditions. Further diseases and conditions of the intestines, liver, kidneys, spleen, and pancreas may also cause a dog to throw up blood. That is why this can be a very confusing problem to try to figure out by yourself, you really need the help of your veterinarian for this one.

It can be a confusing and frightening experience if you suddenly find your dog vomiting blood. Therefore, we have compiled a quick checklist for what you should do:

What To Do If Your Dog Vomits Blood?

  1. Collect a sample
  2. The color and appearance of the vomit can often help to figure out where the bleeding is coming from.

  3. Call your vet

  4. It can be very helpful to call your vet, let them know what happened and let them know you are on your way to the clinic, that way that can have a veterinarian or veterinary nurse ready and waiting to admit your pooch

  5. Check for poison ingestion
  6. Have a quick look around to check if your dog ingested anything strange e.g. rat poison, household cleaner, foreign objects. Often your dog will have left behind some evidence!

  7. Bring the packaging
  8. If your dog did eat something toxic or poisonous, it is really important to bring the packaging or write down the active ingredient names. If your veterinarian has all the information straight away it is much easier to diagnose and rapidly treat your dog.

  9. Go to the vet clinic
  10. Tell your vet about your dog’s recent clinical signs and behavior.

  11. Diagnosis
  12. Allow your vet to carry out diagnostic tests if necessary, to find the underlying cause.

  13. Treatment

Discuss the treatment options with your vet, and follow the recommended treatment plan.

Diagnosing Bloody Vomit In Dogs

The long list of possible underlying causes combined with the fact that many are very serious and life-threatening for your pooch means that you should seek veterinary help quickly if you notice your dog vomiting blood.

The diagnosis may be straightforward if you have witnessed your dog eat something he shouldn’t such as garbage or rat poison. However, most of the time your dog will throw up blood suddenly without many clues as to how it all started.

The vet will take a history and perform a full clinical examination. Most dogs will require blood tests to check their red blood cell and platelet levels, organ health screening, and blood clotting profiles. X-rays and ultrasound scans may be completed to check for foreign objects, cancer or internal bleeding. Urine screens and fecal analysis may be completed to check for internal bleeding, infections or parasites. An endoscopy (tiny camera passed via the mouth) may be recommended to fully visualize the inside of the stomach and intestines.

Treatment Options

The treatment required when a dog vomits blood varies a lot depending on the underlying cause. Sometimes treatment can continue at home if the cause has been diagnosed and the vomiting is mild with only traces of blood. The dog will often be sent home with several prescription medications to heal stomach ulcers and reduce the amount of stomach acid being produced, to reduce nausea and improve the dog’s appetite.

In other cases, the dog may require intensive treatment and hospitalization in the vet clinic to save its life. In cases of internal bleeding, then the dog may require emergency treatment for haemorrhage or shock, including intravenous fluids and blood transfusions.

Internal bleeding may require emergency surgery to find and stop the source of the bleeding. Surgery will also be required for foreign body removal or intestinal obstruction. If a clotting disorder is causing your dog to vomit blood, then your dog may need a blood transfusion to give him extra red blood cells or platelets, vitamin K injections, or immunosuppressant’s (e.g. corticosteroids) to stop immune disorders- it all depends on what the underlying condition is!


It can be a scary experience if your dog vomits blood. Try to stay calm, collect a sample and make your way to your veterinary clinic. Your veterinarian will be able to work out if your dog has a serious life-threatening condition or something less worrisome like a small cut in his mouth causing the bleeding. It really isn’t something you should try to diagnose or treat at home, as there are so many possible underlying causes.