Why is my dog throwing up blood? Here’s why and what to do about it

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Why is my dog throwing up blood? Here’s why and what to do about it

  • 8 min read

Dr. Ruth MacPete, DVM

As a pet parent, seeing your dog vomit is traumatic enough, but seeing them vomit blood is downright scary. Why do dogs vomit blood? What are the different causes? What should you do if they vomit blood? How is it treated? There are many different reasons for hematemesis, the medical term for vomiting blood, but all of them are serious and require a visit to your veterinarian. 

How can you tell if your dog is vomiting blood? 

It seems like a silly question, but realizing that your dog is vomiting blood may not be straightforward. Hematemesis, the medical term for vomiting blood, can look different depending on the nature of the bleeding. Most pet parents will recognize the presence of frank blood. Though the amount of blood can vary, frank blood will be bright red and will be recognizable as blood. Acute or sudden bleeding from the mouth or esophagus is usually associated with frank blood in the vomit. However, blood that has been in the stomach for any length of time will have a very different appearance. Blood will coagulate, or clot, and stomach acid and enzymes will partially digest it. So instead of appearing red and looking like red blood, it will be brown and granular, like coffee grounds. In fact, because of its striking similarity in appearance, this type of bloody vomit is medically known as coffee ground emesis.

What is causing the blood in your dog’s vomit?

Now that you have determined that your dog is vomiting blood, what is next? There are many different reasons why your dog may be vomiting blood. All of them are serious and require a visit to the veterinarian. Your veterinarian will examine your dog and run diagnostic tests to determine the cause of blood in your pet’s vomit. Here are some of the possible causes of hematemesis (blood in vomit):

Foreign objects

One common cause of blood in vomit happens when a dog chews on a foreign object and develops lacerations in their mouth or esophagus. Since the bleeding is acute, it usually appears like frank blood in their vomit. You should have a high index of suspicion if your dog is a chewer, especially if they have a fondness for chewing sticks or bones. Sticks and bones can splinter and cause lacerations to the oral or esophageal mucosa. Your veterinarian will examine their mouth carefully for the presence of foreign objects or lacerations. If your veterinarian suspects a foreign body in their esophagus, they may recommend x-rays or endoscopy.


Tumors of the mouth, esophagus, or stomach can lead to blood in vomit.  Depending on the location of the lesion and the amount of bleeding, the appearance can vary from streaks of blood to coffee ground vomit. Associated signs and symptoms include weight loss and blood in stool, which can have a black tarry appearance. Your veterinarian will perform a complete physical examination, and may order additional studies, like lab work, x-rays, CT scan, ultrasound, a barium study, or endoscopy.


In dogs, inflammatory bowel disease (IBD) is a condition caused by chronic inflammation of the gut lining. The actual cause of inflammation is usually unknown but can be due to infection (bacterial or parasitic) or the gut’s reaction to a protein in their diet. Most dogs with inflammatory bowel disease will have diarrhea although some will have diarrhea and vomiting. Your veterinarian will examine your dog and may order endoscopy with tissue biopsies, a fecal to look for parasites, and lab work.

Clotting problems

Coagulopathy refers to problems with blood clotting and can cause of variety of bleeding-related complications, including vomiting blood. Coagulopathy can be due to a variety of different reasons, such as liver disease that affects the liver’s ability to make clotting factors, hereditary disorders like Von Willebrand’s disease that affect platelet function, leukemia that invades bone marrow and disrupts platelet production, diseases like disseminated intravascular coagulopathy that “consume” platelets, low platelets due to infections (tick-borne illnesses) or autoimmune disorders (immune thrombocytopenia), hereditary disorders like hemophilia that affect production of clotting factors, and toxicity with drugs that affects clotting, such as rat poison (warfarin) or NSAIDS. Since the list of possible underlying causes is rather broad, your veterinarian will need to obtain a detailed history and perform a complete physical examination. The diagnosis can be established by ordering tests that check clotting or platelet numbers.


As mentioned already, rat poison can lead to hematemesis by affecting clotting factors. Other chemicals can be corrosive and irritate a dog’s esophagus or stomach leading to gastric upset, vomiting and hematemesis. Likewise, some plants, like sago palms, are toxic to pets when ingested and can cause your dog to vomit blood. 


An ulcer occurs when there is breakdown of the gastrointestinal lining. This can be due to a variety of reasons, such as medications (steroids, NSAIDS), inflammatory bowel disease, metabolic disorders that affect the liver, kidney, or adrenal glands, toxicity from heavy metal poisoning, cancers of the gastrointestinal tract, and infections with helicobacter species.


Pancreatitis refers to inflammation of the pancreas. In dogs, the most common cause for pancreatitis is dietary indiscretion, which is the medical term for eating something that they should not. Unlike their wild relatives, domestic dogs are not used to eating fatty foods. When dogs eat human food or trash, it can cause inflammation of the pancreas. The symptoms of pancreatitis are abdominal pain, vomiting, diarrhea, lethargy, and lack of appetite. Pancreatitis is diagnosed by ordering blood work that measures the levels of pancreatic enzymes, like amylase, lipase, and trypsin-like immunoreactivity (TLI) and/or an abdominal ultrasound.


Some types of parasites like hookworms and whipworms attach to the intestinal lining and suck blood. These parasites have anticoagulants in their saliva to prevent blood from clotting. Although hookworm and whipworm infestations typically cause anemia, hematemesis may occasionally be seen.

What should you do if you see blood in your dog’s vomit?

Vomiting blood is a serious problem. If you see blood in your dog’s vomit, take your dog to the veterinarian. Your veterinarian will examine your dog and order tests to find the underlying cause of the problem. Your veterinarian needs to identify the reason for hematemesis before they can initiate treatment.


After examining your dog, your veterinarian will likely recommend diagnostic testing to help determine the cause of your dog’s vomiting.  Here are a few of the tests your veterinarian might recommend and how they can help them determine the cause. 


In order to determine the cause of bloody vomit, your veterinarian will likely recommend a complete blood work panel that includes a blood count to determine if your pet is anemic and also a chemistry panel to look for organ function, electrolytes and more. In addition, they may want to do special blood tests that determine if your pet may have a bleeding disorder, also known as coagulopathy. Additional tests, like a pancreatic lipase immunoreactivity test, to determine if your pet has pancreatitis, serum gastrin to determine if your dog has a gastrinoma, and bile acid tests (pre and post-prandial) to look for liver issues.


If your veterinarian suspects parasites, they will order a fecal test. A fecal test requires a fresh stool sample. Using a microscope, your veterinarian will look for parasite eggs and larvae. 


Your veterinarian will likely want to do abdominal radiographs to look for foreign objects, fluid or masses in the abdomen, and more. Sometimes they might need to do a series of radiographs using contrast to improve the sensitivity of the study. Veterinarians can also use abdominal ultrasound to get more information about your dog’s gastrointestinal tract and why they are vomiting up blood. If there is a concern that the blood is coming from the esophagus, they may need to take radiographs of the neck and chest as well. Endoscopy, which involves inserting a long flexible tube with a video camera to examine the esophagus, stomach and small intestine, may also be necessary. During this procedure, your veterinarian may take small samples, or biopsies, to diagnose cancer, ulcers, and more. In dogs, MRI and CT scans are rarely done for abdominal problems due to the need for anesthesia and their expense.


Treatment varies based on cause! 

Since the causes of hematemesis are extensive, the treatment depends on the underlying cause. Your veterinarian will take a history, perform a physical examination, and likely need to order imaging and blood work to establish the diagnosis. The urgency for the treatment also depends on the cause and extent of the bleeding. 

For example, hematemesis due to eating rat poison (warfarin), is an emergency and can be fatal if not promptly treated. Warfarin poisoning is treated by giving vitamin K which reverses the effect of warfarin. Likewise, hematemesis from a foreign body can be an emergency if the foreign body causes an obstruction or perforation. In this case, the treatment is emergency surgery to remove the foreign body and/or repair the perforation. Other causes of hematemesis may require chronic medical treatment. 

For example, treatment for inflammatory bowel disease may include diet changes and medications, like steroids. Hematemesis due to bacterial or parasitic infections is treated with antimicrobials. Pancreatitis may require hospitalization and is often treated with supportive care (IV fluids), antiemetics (vomiting medications), and possibly antibiotics. Despite the various treatments (depending on the cause), the first goal of treatment is always to stop the bleeding. The next goal is to stop symptoms your dog may have like vomiting, nausea, pain and inappetence. 


Of course, the best treatment is always prevention. One of the most common causes of hematemesis in dogs is due to giving pets human medications. Many people do not realize that dogs are more sensitive to common over-the-counter human medications. Unfortunately, people often give their pet human medication thinking they are doing something to help their pet. For example, if their dog has arthritis, they may give them ibuprofen, thinking it will help alleviate their pet’s pain. Unfortunately, if not properly dosed for their dog, ibuprofen can cause a gastric ulcer and hematemesis. Likewise, giving your pet another pet’s medication can also be dangerous. Medications are dosed based on weight and health. Giving an older chihuahua in kidney failure your 90 lb. Doberman’s medication can be deadly. 

To be safe, never give your dog human medications, even over-the-counter medications, or another pet’s medications without consulting with your veterinarian first. 


Poisons like rodenticides or rat poison are a major cause of hematemesis in dogs and a very preventable one. Be sure to keep all poisons, especially deadly chemicals like rat poison, locked away from pets. If you have dogs or cats, ideally avoid using these types of poisons as curious pets often get into poison or may come in contact with a poisoned rat.  Likewise keep all chemicals safely out of reach of pets. 


If you have pets, check your house and yard to ensure that you do not have any plants that are toxic to pets. The list of poisonous plants is extensive. For a list of toxic plants, consult the ASPCA’s pet poison control. https://www.aspca.org/pet-care/animal-poison-control 

If you have a puppy or dog that chews up things, the best way to keep them safe is to puppy proof your house. Keep items that can be ingested like shoes, clothing, rocks, sticks away from pets. Fence off areas in your yard that have rocks and sticks and put away stuff in the house or crate your dog to make ingestion of foreign bodies less likely.

Parasitic infections are easy to prevent by keeping your pet on year-round parasite preventatives. Depending on the year-round preventative, it can also keep your dog free from heartworm, fleas and ticks.

While not all causes of hematemesis are preventable, routine wellness visits are the best way to detect illnesses early. Early detection generally leads to early intervention and better outcomes. 


Hopefully, this blog has given you some idea of why your dog might be vomiting blood and some ways to prevent this scary thing from happening in the first place. Most importantly, remember that if your dog vomits blood, any amount, call your veterinarian right away for advice or bring them in to your veterinarian or your local veterinary emergency clinic.

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