When your dog is throwing up and has bloody diarrhea, it can be alarming and confusing. These symptoms often point to a serious health issue that requires immediate attention.
We outline the common causes of dog throwing up and bloody diarrhea, what signs to watch for, and what actions you should take. Whether it’s a one-time incident or a repeated problem, understanding the underlying causes can make all the difference in your dog’s health and recovery.
Dog Throwing Up and Bloody Diarrhea: Why It Happens
Dog throwing up and bloody diarrhea happens due to irritation, inflammation, or damage within the digestive system, often caused by infections (like parvovirus or bacterial gastroenteritis), ingestion of toxins, dietary indiscretion, parasites, or more serious conditions like hemorrhagic gastroenteritis or gastrointestinal ulcers.
These issues disrupt the lining of the stomach and intestines, leading to vomiting and the presence of blood in the stool.
It’s a sign of a potentially serious underlying condition that requires veterinary evaluation to prevent dehydration and other complications.
Dog Throwing Up and Bloody Diarrhea: Common Causes
Gastrointestinal infections
One of the most common causes of dog throwing up and bloody diarrhea is a gastrointestinal infection.
Bacteria like Salmonella or E. coli, viruses such as parvovirus, or intestinal parasites like hookworms and Giardia can all trigger violent gastrointestinal upset.
These pathogens irritate and inflame the gut lining, causing both vomiting and blood-streaked or dark, tarry diarrhea.
Puppies and unvaccinated dogs are especially at risk, particularly with deadly viruses like canine parvovirus.
A dog infected with these pathogens may also show signs of lethargy, fever, or loss of appetite.
Since these infections can spread rapidly or be fatal without treatment, a dog throwing up and bloody diarrhea from an infection must see a vet immediately.
Related: Dog is Vomiting, Has Diarrhea, and Not Eating (Causes and treatment)
Ingestion of toxins or foreign objects
Dogs are naturally curious and often chew or swallow things they shouldn’t. Consuming toxic substances—like chocolate, xylitol, rat poison, household cleaners, or even spoiled food—can lead to both vomiting and intestinal bleeding.
Toxicity can damage the stomach and intestinal lining, resulting in blood in the stool.
In some cases, a dog may vomit blood as well.
Foreign objects like toys, bones, or socks can also obstruct the digestive tract, leading to repeated vomiting and bloody diarrhea due to tissue damage or internal pressure.
If your dog is throwing up and passing bloody stool, and you suspect they may have eaten something dangerous or indigestible, it’s an emergency.
Hemorrhagic gastroenteritis (HGE)
Hemorrhagic gastroenteritis, or HGE, is a condition characterized by sudden and severe vomiting combined with bloody, often jelly-like diarrhea.
The cause is often unknown, but it’s thought to be linked to stress, bacterial infections, or dietary indiscretion.
Dogs with HGE can become critically dehydrated in a matter of hours due to fluid loss.
While it can affect any breed, smaller dogs like Toy Poodles and Miniature Schnauzers are more prone.
If your dog is throwing up and bloody diarrhea appears suddenly and in large amounts, this could be a sign of HGE and needs immediate veterinary care.
Dietary indiscretion or food allergies
A sudden change in diet, eating table scraps, garbage, or spoiled food can irritate your dog’s stomach and intestines.
This is referred to as dietary indiscretion.
Some dogs also have food allergies or intolerances that can trigger vomiting and bloody diarrhea, especially if the allergy causes inflammation of the gut lining.
While some cases are mild, others can escalate quickly, particularly if the food was contaminated or led to pancreatitis.
Always transition your dog to new foods gradually and avoid feeding unfamiliar human foods to prevent digestive distress.
Inflammatory bowel disease (IBD)
Inflammatory bowel disease is a chronic condition where the gastrointestinal tract becomes inflamed due to an abnormal immune response.
Dogs with IBD may experience recurrent vomiting, diarrhea, and weight loss.
In more severe cases, the stool may contain blood or mucus.
While IBD is not usually life-threatening in the short term, it is a cause of chronic dog throwing up and bloody diarrhea and requires long-term management with diet changes, medications, and sometimes immunosuppressive therapy.
Intestinal parasites
Parasites like hookworms, whipworms, and Giardia are notorious for causing both vomiting and bloody diarrhea in dogs.
These parasites damage the intestinal lining as they feed, leading to inflammation and bleeding.
Puppies, rescue dogs, or those who have not had regular deworming are especially at risk.
Infected dogs may have visible worms in their stool or exhibit other signs such as bloating, gas, and weight loss.
Regular fecal exams and preventive deworming are essential to keeping your dog parasite-free.
Stress and anxiety
While it may seem surprising, stress can cause gastrointestinal upset in dogs. Significant changes in environment, loud noises, separation anxiety, or travel can lead to vomiting and diarrhea, occasionally with blood.
Stress affects gut motility and can alter the balance of bacteria in the digestive system.
This condition, sometimes called stress colitis, is more common in nervous or anxious dogs.
The symptoms often resolve once the stressor is removed, but persistent cases may need medical management.
Related: Dog throwing up and drinking a lot of water (What it means)
Side effects of medication
Certain medications, especially NSAIDs (nonsteroidal anti-inflammatory drugs), antibiotics, or corticosteroids, can irritate the stomach lining or disturb the gut microbiome.
This can result in vomiting and bloody diarrhea in some dogs.
If your dog starts showing these symptoms shortly after beginning a new medication, speak to your vet right away.
Do not stop any prescribed medication without professional guidance, as stopping suddenly can also cause harm.
Cancer or tumors
In older dogs, gastrointestinal tumors or cancers like lymphoma can cause chronic vomiting and bloody diarrhea.
These conditions can disrupt the normal function of the digestive system and may result in ulceration or bleeding.
Though rare, cancer should be considered, especially if symptoms persist despite treatment or if your dog is losing weight rapidly and appears generally unwell.
What to do if your dog is throwing up and has bloody diarrhea
If your dog is throwing up and bloody diarrhea is present, it’s important not to panic—but you do need to act fast. Here’s what to do:
1. Call your veterinarian immediately
These symptoms are rarely mild and can worsen rapidly.
Even if your dog seems alert, blood in the stool or vomit is not normal and warrants a professional evaluation.
Explain the timeline, appearance of symptoms, and anything your dog may have eaten.
2. Withhold food temporarily
Unless otherwise directed by your vet, you can withhold food for 12–24 hours to allow your dog’s stomach to settle.
Make sure they still have access to fresh water unless vomiting persists.
Never withhold water without veterinary approval.
3. Collect a stool or vomit sample
If possible, collect a fresh sample to show your vet.
It can help with diagnostics, especially if parasites or toxins are suspected.
Take note of the color, texture, presence of blood, or unusual objects.
4. Do not give human medications
Over-the-counter medications like Pepto-Bismol or ibuprofen are dangerous to dogs.
Never give your dog any human drug unless prescribed by your veterinarian.
5. Monitor for signs of dehydration
Check for dry gums, sunken eyes, loss of skin elasticity, and lethargy.
Dehydration is a serious risk when your dog is throwing up and has bloody diarrhea, especially in puppies or small breeds.
6. Follow through with diagnostics and treatment
Your vet may recommend blood tests, X-rays, ultrasound, or fecal exams to determine the cause.
Treatments may include IV fluids, anti-nausea medications, antibiotics, dewormers, or hospitalization depending on the severity.
Key takeaway
Dog throwing up and bloody diarrhea can stem from a range of causes—some mild, others life-threatening.
While a single episode may pass without concern, the combination of vomiting and blood in the stool is a red flag that should never be ignored.
Whether it’s an infection, poisoning, parasites, or inflammation, swift veterinary care can prevent complications and save your dog’s life.
If your dog is throwing up and has bloody diarrhea, act quickly.
The sooner the cause is identified and treated, the better your pet’s chances for a full recovery.