Dog Vomiting Blood: A Step-By-Step Guide

By Petal Smart / July 16, 2018

We know that your dog means the world to you. At Honest Paws, we are all pet lovers and dog owners. For that reason, we understand how heart-wrenching it can be when your dog isn’t feeling quite like themselves.

Furthermore, we understand how terrifying and worrisome it can be to see your dog vomiting blood. It’s hard to not go into a full-on panic mode when you discover something like bloody vomit, however, try to remain calm.

There are a number of reasons why your dog may be vomiting blood, and it’s imperative to figure out the underlying causes in order to treat it properly and effectively.

A proper veterinary diagnosis will be necessary to determine exactly what is wrong with your pup. We don’t have to tell you that it’s not normal for your dog to throw up blood, but the faster you get a diagnosis, the better the chances for a full recovery.

In this article, we hope to inform you of what may be causing the bloody vomit, and how to proceed in getting your dog the best care possible.

Dog Vomiting Blood

What is Hematemesis: An Overview

Hematemesis is the medical term for vomiting blood. There are a number of potential causes for vomiting blood (hematemesis). Blood in your dog’s vomit may be the result of a disruption in the esophagus. The esophagus is the tube that connects the mouth or throat to the stomach. 

Another potential reason for blood in your dog’s vomit could be an irritation of the intestines or the stomach. This irritation can, therefore, lead to inflammation, internal bleeding, and the expulsion of blood through vomit.

Furthermore, A relatively common cause of blood in vomit is the ingestion of a foreign object. This foreign body can cause inflammation or injury to the mouth, esophagus, lungs, stomach, or other organs. If and when the foreign object is thrown up, it is often accompanied by blood.

Depending on the source of the problem, hematemesis can affect several different parts of the dog’s physiological systems. For example, the gastrointestinal system may be affected by the ingestion of a foreign body, inflammation, trauma, parasites, poisoning, certain drugs, or an ulcer.

The cardiovascular system may also be affected by hemorrhage, particularly if it has been ongoing for an extended duration or a considerable volume of blood has been lost. Additionally, if your dog has a clotting disorder, the stomach and/or intestines (among other organs) are often affected. These conditions, among others, can all ultimately lead to hematemesis.

Signs of Hematemesis in Dogs 

Obviously, the primary sign of hematemesis is the presence of blood in the vomit. But what pet parents may not know is that the blood can appear in several different forms.

The blood may be fresh blood, digested blood (which resembles coffee grounds), or may appear as clots. Additional signs often include a lack or loss of appetite, stomach pain, and black tarry diarrhea (called melena).

Your vet would be able to determine whether your dog may be anemic (have a low red blood cell count), have a rapid heart rate, heart murmur, and/or overall weakness.

Dog Vomiting Blood

What It Means if Your Dog is Throwing Up Blood

Now, let’s get down to the specifics.

The least worrisome explanation for the appearance of blood in your dog’s vomit could be a cut in the mouth from chewing on an object such as a bone, or perhaps while playing with another dog.

However, a dog vomiting blood could also be a sign of internal bleeding further along the digestive tract or from other organs. Furthermore, other more severe conditions can also cause blood in the vomit, such as the parvovirus infection, or even cancer.

We don’t want to scare you any more than necessary, but we do want to stress that it is paramount to see a vet in a timely manner, particularly if you find more than a few streaks of blood in your dog’s vomit.

Blood in Mucus 

Pet owners will also want to learn to differentiate and recognize what kind of blood they may find in their dogs vomit. If you find vomit that is high in mucus and what looks like fresh red blood, the upper parts of the gastrointestinal tract (mouth, esophagus, and stomach) may be bleeding, ulcerated, or inflamed.

When the blood is a darker red or has a tarry appearance, it usually means that the blood has already been partially digested in the stomach, or the bleeding has been going on for some time. This dark red, tarry blood may also smell bad.

A diagnosis from your vet will be necessary to determine the source of the blood unless it is obvious to the pet owner. The vet will likely ask you a series of questions, including all of the things that your dog may have gotten into and eaten.

It is important to provide your vet with all the information that you possibly can. This will help to achieve a timely diagnosis and development of an appropriate treatment plan.

Additionally, if possible, carry a sample of the vomit, and before cleaning it up, take a picture of the fresh vomit to show the appearance of the blood to your veterinarian. This will also help to speed up the diagnostic process. Be prepared for some blood tests, if possible, analyses of the dog’s urine and feces, and perhaps even some x-rays. It may seem extensive, but if the vet has opted to perform these tests, it’s because they are necessary.

Dog Vomiting Blood: Causes

There could be many reasons why your dog may be throwing up blood. While a proper diagnosis from a veterinarian is mandatory in the majority of cases, we hope to provide you with some details of the possible causes of bloody vomit.

The first step to figuring out the cause of the bloody vomit is to recognize its appearance. If the blood is fresh, it will typically be bright red. The blood may look like red streaks or specs.

You may also find bright red clots in the vomit. As mentioned previously, if the blood is older or has already begun to be digested in the stomach, it will be darker. Partially digested, older blood typically looks like dark coffee grounds.

It is important to note the color of the blood because this will help the vet to determine how long the bleeding has been going on, and pinpoint the part of the dog’s digestive tract that may be bleeding.

Typically, bright red vomit is a sign that the bleeding is occurring in the mouth, throat, esophagus, or stomach.

Dark red blood may mean that the dog has a stomach ulcer or has been bleeding for a prolonged duration.

Furthermore, when your dog throws up from drinking water too fast or eating as if it’s a race, the vomit should either be clear (watery) or simply regurgitated or undigested food. (Regurgitation tends to be a much more passive process, and is not usually accompanied by the forceful heaving and general signs of discomfort that accompany vomiting.)

Now we aren’t saying that this is normal, your dog shouldn’t be vomiting on a regular basis. If your dog is vomiting (or even regurgitating) regularly without explanation, it is important to seek veterinary intervention regardless of the presence or absence of blood.

Even if you notice no blood in your dog’s vomit, there may still be an underlying issue that needs to be addressed.

Chewing on Bones 

We want to start off by saying that we aren’t exactly advocates for dog bones. Bones and other animal byproducts such as rawhides can cause various issues for Fido’s digestive tract.

Nevertheless, dogs have apparently been chewing on bones long before they were domesticated members of family households, and we understand that some of our readers may presently purchase bones for their dogs. We just want everyone to be aware of the potential dangers.

If the bones that your dog is chewing happen to shatter, they will typically break into sharp pieces. While many of these sharp pieces may be broken down by the acid of the dog’s stomach, they do have the potential to cause injury to the esophagus, stomach, and/or intestines.

This can cause a slew of conditions, including peritonitis, one of the most severe. Peritonitis occurs when bacteria and other substances leak through a hole in the intestines into the abdominal cavity, where it can have a more generalized adverse effect. In the majority of cases, peritonitis is life-threatening.

If your dog vomits blood after eating a bone, it could be due to a cut in the mouth from the shattered, sharp pieces of bone. However, it is also possible that these tiny fragments could get stuck in the dog’s throat, esophagus, and/or stomach. Depending on where the bone gets stuck and the degree of blockage, emergency surgery may be necessary.

Dog Vomiting Blood from Chewing on Bones

Ingesting Foreign Objects

All dogs seem to love getting into things that they shouldn’t. Most often, if something smells good, your dog will take a bite. This is known as dietary indiscretion.

One of the most common causes of a dog vomiting blood is the ingestion of something that they shouldn’t have eaten. This often occurs with puppies, but trust us when we say that dogs of all ages love to eat trash.

Bloody vomit can be the result of eating just about anything – edible or inedible!. For example, socks, jewelry, tennis balls, paper, coins, you get the idea.

Another cause of bloody vomit is the ingestion of something poisonous to dogs, such as garlic. There are a number of food items that humans consume that are potentially toxic to dogs, particularly if an excessive amount is ingested.

This type of poisoning will likely cause the dog to vomit blood. 

Antifreeze Poisoning 

Vomiting blood could be an early sign of antifreeze poisoning. A scary and little-known fact is that less than 3 ounces of antifreeze is enough to fatally poison a mediumsized dog.

Even with immediate treatment, antifreeze poisoning can be life-threatening and deadly. Therefore, if you have any reason to believe that your dog has ingested antifreeze, it is imperative to seek emergency veterinary treatment right away.

Dog Vomiting Blood from Ingesting Anti-Freeze


One of the deadliest diseases among dogs and puppies is the parvovirus infection. Unfortunately, a dog vomiting blood could be a sign of the deadly virus.

Therefore, it is critically important to seek veterinary attention straight away if your dog is throwing up blood.

If your dog gets parvovirus, they will become extremely sick very quickly. There is no cure for parvovirus.

But with aggressive emergency treatment, survival is possible. However, the chances of survival are considerably reduced once bloody vomit becomes evident.

Stomach Ulcer 

We previously mentioned the importance of being able to recognize and differentiate the appearance of blood in your dog’s vomit. If it looks like coffee grounds, it is typically a sign of a stomach ulcer or bleeding in the stomach.

Humans and dogs can both suffer from stomach ulcers and if you’ve ever had one, you know how painful they can be. Stomach ulcers are sores on the inner lining of the stomach.

Oftentimes, it is difficult to treat a stomach ulcer because it is constantly within the same acidic environment in which it was developed in the first place.

Stomach ulcers may be caused by medications such as painkillers, aspirin, and/or steroids. The ulcers can lead to chronic inflammation and bleeding, and thus, may cause bloody vomit.

Bacterial Infection 

Another reason for the appearance of blood in the vomit of dogs could be an underlying bacterial infection.

Food poisoning or bacterial infections with Salmonella, E. coli, Campylobacter, Clostridia, and other forms of bacteria will more than likely lead to bloody vomit.

Bacterial infections in dogs show signs that are similar to bacterial infections in humans. These signs include loss of appetite, fatigue, generalized pain, bloody diarrhea, and/or fever, as well as bloody vomit. Again, a veterinarian will need to diagnose the bacterial infection to prescribe appropriate treatment. 

Food Allergy 

We don’t have to tell you that dogs can be highly sensitive creatures. Just like humans, dogs can be allergic to their food. Vomiting is a typical response to a food allergy.

Vomiting usually develops quickly after switching to a new food. However, it’s also possible for your dog to gradually become allergic to food, even if they’ve been eating it for years.

If the dog’s food allergy is severe, they may vomit blood. Food allergies may also cause bloody stool and severe abdominal pain. Food additives are usually responsible for most of the common food allergies.

These additives include sweeteners, preservatives, flavorings, etc. Other typical food allergies may be caused by wheat, dairy, eggs, corn, and fish.

Unfortunately, there’s no easy way to figure out exactly what your dog is allergic to, other than by trial and error.

While it can be time-consuming and a bit costly, it’s worth figuring out what your pup is allergic to. Once the allergens are removed, you can base their diet on nourishment that won’t cause an upset stomach.

Dog Vomiting Blood from Food Allergy

Blood-Clotting Disorders

Bloody vomit that is caused by internal bleeding is often due to an underlying blood-clotting disorder.

It may also be due to an underlying condition such as liver failure or cancer. Furthermore, if the dog is exposed to pesticides and toxins, additional problems may arise that ultimately lead to defects in blood clotting and therefore, vomiting of blood.

Again, this is why it is so important to make an appointment with your veterinarian at the first sight of blood in your dog’s vomit.


Some parasites, such as hookworms, disrupt the lining of the intestines in dogs. These parasites attach themselves to the inner walls of the intestines and feed on blood.

If there are a high number of parasites within the intestinal tract, the dog will likely vomit blood. It’s also likely that the dog may have bloody stool.


Bloody vomit may also be a sign of cancer. While there are many forms of cancer in dogs, the cancer most associated with bloody vomit is cancer of the stomach.

Esophageal tumors and stomach tumors also have the potential to cause bloody vomit. While vomiting blood is definitely not the only sign of cancer in dogs, it may be among the first to become evident.

Bilious Vomiting Syndrome 

Specks of blood may be evident in the vomit if the dog vomits on an empty stomach (known as bilious vomiting syndrome). If the dog hasn’t eaten for several hours (such as in the early morning or late at night), a build-up of bile may irritate the lining and smaller blood vessels of the stomach. Although blood may be evident, vomit in such cases would also show a yellow-green color due to the presence of bile.

Long-Term Stomach Inflammation 

Chronic gastroenteritis, or long-term stomach inflammation, is another potential cause of bloody vomit.

The bleeding occurs as a result of intermittent vomiting and inflammation of the stomach lining. The inflammation of the stomach lining could be due to autoimmune diseases, metabolic or endocrine diseases, hyper-acidic syndromes, or other conditions.

Hemorrhagic Gastroenteritis (HGE) 

Sometimes the bloody vomit is accompanied by bloody diarrhea that seems to arise without explanation. One possible reason for this condition is Hemorrhagic Gastroenteritis (HGE).

The vomiting and diarrhea typically start with mucus and bile and then become bloody as they continue. HGE can be especially dangerous for small dogs as the loss of fluids can lead to dehydration and possibly kidney failure.

Even with extensive research, experts are still not fully aware of the main cause of HGE. However, we do know that factors such as stress, anxiety, allergic reactions, and dietary changes can all contribute to HGE.

Other Health Issues 

Additionally, diseases of the liver, kidney, spleen, and pancreas can all lead to bloody vomit.

Other general signs that may accompany these diseases include loss of appetite, generalized weakness, abdominal pain, diarrhea, weight loss, and/or excessive thirst.

Blood in Vomit: What To Do 

We want to reiterate that although seeing blood in your dogs vomit may cause you to panic, try to stay calm.

If possible, collect some of the bloody vomit and put it in a sealed plastic bag or container to take with you to the vet’s office. Taking a picture on your phone is also useful.

Additionally, consider all the possible things your dog may have consumed, which they shouldn’t have, as well as any changes or new components in your dog’s diet or lifestyle (i.e., moving homes, new interactions with other dogs, etc.)

The more information that you’re able to provide your vet, the more efficiently a diagnosis can be made. For the vast majority of conditions associated with bloody vomit, a timely diagnosis is absolutely imperative.

How to Diagnose A Dog Throwing Up Blood 

As we have mentioned seemingly countless times in this article, making an appointment with your veterinarian is the best and most efficient way to determine why your dog is vomiting blood.

We want to warn our readers that the diagnosis may not come easily. Depending on the underlying cause of the bloody vomit, your veterinarian will likely need to do a series of tests.

These tests include a complete blood count, organ screening, fecal analysis, blood clot profile testing, and x-rays, among others.

While the tests may be extensive, they present the best chances of a prompt diagnosis, and thus, a full recovery. Even after your dog has recovered, you should still be careful to avoid the triggers that can lead to another bout of vomiting.

Dog Vomiting Blood: The Bottom Line

At the end of the day, we know how scary it can be to see blood in your dog’s vomit. No one said that being a pet owner was going to be easy.

Yet, when problems arise, it can be incredibly frustrating and heart wrenching for a dog owner.

Not knowing what to do and being unsure of what is causing the problem can be beyond stressful.

However, recognizing that there is a problem is the first step to fixing it. We cannot stress enough that if you see unexplainable blood in your dog’s vomit, do not delay to visit the vet or emergency clinic.

While simple mouth abrasions may heal on their own, the vast majority of underlying conditions causing bloody vomit will not. We encourage you to talk to your veterinarian ASAP.

Prompt diagnosis and proper treatment are your dog’s primary ways of getting better soon. We know this can be a worrisome time, but there is certainly hope.

Don’t delay in getting your pup the treatment they need. 

Sources…care/my-dog-is-vomiting-blood-what-should-i-do › Dogs › Health Problems

About the author

Petal Smart

Dr. Petal Smart is a veterinarian who, after a brief stint in clinical practice, has been a medical, veterinary, and science editor for the past four years. She has edited hundreds of research studies that have been published in various academic journals, and more recently, she has been editing blog articles on pet health. She holds a DVM (Hons) from the University of the West Indies - St. Augustine. Her pets in the past have included dogs, fish, birds, and a turtle. At times, she also likes to think of herself as a horse whisperer. You can connect with her on LinkedIn.

  • Molly says:

    Thanks to all who put this article together. It’s very informative while delivering the message gently. Your article gave me the information so I got my girl to the vet asap.
    Thanks again

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