Why Is My Dog Vomiting Blood?

Reviewed by: Dr. Robert Menardi, DVM

Vomiting is a fact of life for any pet parent and dogs largely seem unfazed by the occasional vomit session. However, it can be difficult for you to watch as their human, not to mention the mess to clean up. When your dog throws up blood, however, there is legitimate reason to be concerned. 

What Causes Dogs To Vomit Blood?

Hematemesis, or vomiting blood, is caused by a number of things in dogs. Regardless of the reason, it is not normal for there to be blood in a dog’s vomit. Pet parents should consult a veterinarian as soon as possible in the event of bloody vomit. 

The most likely and least serious cause for blood vomiting is that your pup has cut their mouth while chewing on something sharp. It’s also possible that the inside of your pup’s esophagus, stomach, or intestines is irritated or punctured. This can result in internal bleeding that can be severe or dangerous. 

This section will take a close look at some of the most common causes of canine vomiting blood.

Blood Clotting Issues

Coagulopathy, or lack of proper blood clotting, may result from liver failure, or a reduced blood platelet count (thrombocytopenia) due to toxin or drug exposure. Internal bleeding is sometimes caused by blood-clotting disorders like hemophilia. 

It may also be a sign of low blood platelet count due to underlying illness. Also, certain toxins and pesticides cause blood coagulation issues. For example, rat poison contains anticoagulant/blood thinner agents. 

Cancer

Although more likely in older dogs, any age dogs can be diagnosed with some form of cancer. Bloody vomit may be a first or early symptom of stomach cancer. While stomach cancer is most often associated with vomiting blood, several forms of cancer can also present this symptom. These cancers include esophageal, lung, and pancreatic cancer. 

Hemorrhagic Gastroenteritis (HGE)

This serious condition involves sudden, severe bloody vomiting and/or diarrhea. The cause of HGE is generally unknown, and typically affects young to middle-aged small dogs. 

HGE often comes on suddenly and rapidly progresses in seemingly healthy dogs. It can quickly lead to dehydration and other organ compromise. 

Parasites

Dogs can be susceptible to various parasites that can affect their health and well-being. While many parasites can cause gastrointestinal issues, bleeding in vomit is usually associated with two common parasites:

1. Hookworms: Hookworms are intestinal parasites that can cause bleeding in a dog’s vomit. These parasites attach themselves to the intestinal wall, feeding on the host’s blood, which can lead to internal bleeding. In severe cases, the presence of hookworms may cause bloody or vomit.
   
2. Stomach or Intestinal Ulcers: Though not technically parasites, stomach or intestinal ulcers can be caused by the presence of certain bacteria, such as Helicobacter pylori. These ulcers can lead to vomiting of blood or a coffee ground-like substance.

It is important to note that while these parasites and conditions can cause bleeding in a dog’s vomit, various other factors can contribute to this symptom as well. If you suspect your dog may have parasites or any health concerns, it is crucial to consult a veterinarian for proper diagnosis and treatment.

Parvovirus

Often called “parvo,” canine parvovirus is highly contagious and deadly. The virus impacts a dog’s gastrointestinal tract and progresses very quickly. 

Persistent vomiting and diarrhea lead to severe dehydration and eventual hypovolemic shock, so parvo requires immediate veterinary attention. Bloody vomit is a sign of dangerous illness progression. 

Prolonged Vomiting

Excessive vomiting for any reason can put a strain on and cause inflammation of the stomach, upper intestines, and or esophagus. This can eventually lead to broken blood vessels and internal bleeding. 

Infection

Parasitic infections such as giardia in the intestines can cause bleeding that may be detectable in illness-related vomit. 

Some bacterial infections caused by food poisoning, such as salmonella and E. coli, are common in young dogs or those with weak immune systems. In addition to vomiting blood, these infections may be accompanied by bloody diarrhea, loss of appetite, fever, and or fatigue. 

Inflammation

Several inflammatory conditions can potentially lead to dogs vomiting blood. Here are a few examples:

1. Gastrointestinal Ulcers: Ulcers can be caused by various factors, including inflammation. Inflammatory conditions like gastritis (inflammation of the stomach lining) or duodenitis (inflammation of the duodenum) might result in ulceration and subsequent vomiting of blood.
   
2. Esophagitis: Inflammation of the esophagus, known as esophagitis, can be caused by factors such as acid reflux, foreign body ingestion, or certain medications. Severe cases of esophagitis may lead to bleeding and subsequent regurgitation or vomiting of blood.
   
3. Inflammatory Bowel Disease (IBD): IBD is a chronic inflammatory condition that affects the gastrointestinal tract. It can cause vomiting, diarrhea, and gastrointestinal bleeding, which may manifest as the presence of blood in the vomit.
   
4. Pancreatitis: This inflammatory condition affects the pancreas and can result in abdominal pain, vomiting, and other digestive disturbances. In severe cases, pancreatitis can lead to blood appearing in the vomit.
   

While these conditions can potentially cause hematemesis, only a veterinarian can provide an accurate diagnosis and recommend appropriate treatment options based on a thorough examination and diagnostic tests.

Irritation, Obstruction, or Puncturing of the Digestive Tract

Any damage caused to the stomach and intestines by swallowing a sharp object can cause internal bleeding and bloody vomit. Small sharp food items dissolve fairly quickly in stomach acid. 

However, if they are non-food items, they can sometimes puncture the stomach or intestines, causing peritonitis. In this case, bacteria escape the intestine and can become potentially life-threatening. Foreign objects sometimes require surgery to remove the item from a dog’s digestive system. 

Toxins and Poison

One of the most common causes of bloody vomit is a dog eating something they shouldn’t have. The ingestion of toxins like household cleaners, toxic plants and pesticides, and rat poison can lead to bloody vomit, severe illness, and death.

Traumatic Injury

Your dog can get sick after a traumatic incident, such as being hit by a car, severe burns, heatstroke, major surgery, exposure to poisons from heavy metals, such as excessive iron consumption or lead, and snake bites. These can all cause internal bleeding and or shock.

What Should You Look for When Your Dog Throws Up Blood?

Bloody vomit can look different depending on the cause of the issue. Being able to tell your veterinarian what your pup’s vomit looks like is crucial in helping your vet determine the best next steps. 

The color and appearance of bloody vomit depend on how long the dog has been bleeding internally and what part of the dog’s digestive tract is bleeding. 

Bright Red

Relatively small amounts of fresh, bright red blood seen in the form of specks, streaks, or clots are usually caused by a physical injury and bleeding in the mouth, throat, stomach, or upper intestines. 

Mucus

Vomit that is high in mucus and blood typically indicates that the dog’s stomach or upper intestines are inflamed, ulcerated, or bleeding. Bile is often also present when the source of the irritation is in the upper intestine. 

Dark Red or Brown

If the blood is older or partially digested in the stomach before it was thrown up, the vomit might look like dark coffee grounds. Dark red blood in a dog’s vomit means the blood has been in the body for a longer period of time. 

This indicates that there is likely an ulcer or other source of internal bleeding in the stomach, lower intestines, or elsewhere in the deeper gastrointestinal tract. In addition, if the blood is being digested and goes all the way through the GI tract, you may see very dark to black tar-like stools, which is a sign of a GI bleed somewhere. 

When Is Vomiting Blood Particularly Dangerous?

Vomiting blood can become a profoundly serious health concern very quickly for dogs. It’s important to call the vet as soon as you notice blood in your pup’s vomit. Even a little initial blood may quickly turn dangerous, depending on the cause. Bloody vomit can be particularly dangerous if any of the following occur.

Significant Blood Loss

Loss of blood through vomit may lead to a low red blood cell count (anemia). Additional symptoms can include  weakness to the point of collapse and a rapid heartbeat. Severe blood loss can be fatal or require a blood transfusion.

Your Dog Is a Puppy

Before being vaccinated and or building their immune system, young pups are susceptible to infections (such as Parvovirus). This can quickly become severe and may even be fatal. 

Underlying Illness

Compounded symptoms, such as fever, lethargy, diarrhea, loss of appetite, and inability to keep down food and water, can be particularly dangerous. 

What Is the Treatment for Vomiting Blood?

Treatment for vomiting blood varies greatly depending on the cause of the hematemesis. It typically includes two phases: supportive care and addressing the underlying cause. 

Depending on your dog’s individual needs, supportive care may include prescription antinausea medication and stomach lining protectants, antacids, fluids to address any dehydration and electrolyte loss, prescription or bland diet, and, in severe cases, a blood transfusion. 

Preventing bloody vomit 

Many common causes of bloody vomit are preventable. To avoid the recurrence of bloody vomit, it’s crucial to keep your canine companion up to date on all routine care. This includes vaccinations and parasite prevention. 

In addition to ensuring your dog does not have access to harmful toxins and potentially poisonous substances (cleaners, plants, pesticides), your dog’s diet plays a central role in their digestive and overall health. For dogs with sensitive stomachs or gastrointestinal systems, it may be beneficial to adopt a highly digestible diet.

With any issue, your dog depends on you to advocate for his health, so call your veterinarian as soon as you see that something is not right with your pet, whether it be bloody vomit or something else. At ElleVet, we believe you know your dog the best, and you know when he is off.

Any health or medical information in ElleVet blogs is from a variety of public and reputable sources. This information is intended as an educational resource only and is not a substitute for expert professional care.  

Sources:

Active immune system worsening liver disease in dogs | The University of Edinburgh

Stomach Cancer, Tumors & Abdominal Masses | We Are the Cure

Acute Hemorrhagic Diarrhea Syndrome in Dogs (Hemorrhagic Gastroenteritis) | VCA Hospitals

The canine hookworm Ancylostoma caninum: A novel threat for anthelmintic resistance in Canada | NIH