Seeing your dog sick with diarrhea that contains blood can be one of the most alarming things for any pet owner.
Even a small amount of blood in your dog’s stool can indicate anything from mild irritation to a serious underlying illness that needs veterinary attention.
We outline the common causes of a dog being sick with diarrhea and blood, what you can do at home, and when to seek veterinary help.
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Dog Sick Diarrhea Blood — Why It Happens
A dog throwing up and having bloody diarrhea is often a sign that the digestive system is inflamed or damaged. The most common culprits include dietary indiscretion, infections, parasites, stress colitis, or conditions like hemorrhagic gastroenteritis.
In other cases, toxins, severe dehydration, or organ-related illnesses may cause both vomiting and bloody stools.
The combination of vomiting and diarrhea can quickly lead to fluid loss and weakness, making prompt care essential.
Dog Sick Diarrhea Blood: Common Causes
1. Hemorrhagic Gastroenteritis (HGE)
Hemorrhagic gastroenteritis is one of the leading causes of sudden bloody diarrhea in dogs. It often appears without warning, turning your dog’s stool into a watery, dark red mixture that looks like raspberry jam.
Dogs with HGE may also vomit repeatedly and refuse food or water. The condition causes severe dehydration because fluid leaks from the bloodstream into the intestines.
Small breeds like Miniature Schnauzers and Toy Poodles are particularly prone to HGE, though it can occur in any dog. Without prompt veterinary treatment — often involving IV fluids and medications — it can become life-threatening within hours.
Read more: Dog Pooping Blood After Diarrhea (What it means)
2. Dietary Indiscretion or Food Intolerance
Many cases of dog diarrhea with blood start with something simple — eating something they shouldn’t. Dogs are notorious for scavenging leftovers, spoiled food, garbage, or foreign objects.
When a dog eats something their stomach can’t handle, the gastrointestinal lining becomes irritated, leading to inflammation, vomiting, and sometimes traces of blood in the stool.
Even switching to a new food too quickly or consuming rich treats can trigger digestive upset in sensitive dogs. If the blood is bright red and your dog is otherwise alert, it may be due to lower intestinal irritation, but persistent symptoms need vet evaluation.
3. Parvovirus Infection
Parvovirus (or “parvo”) is a highly contagious and dangerous viral disease that primarily affects puppies and unvaccinated dogs.
The classic symptoms are severe vomiting, foul-smelling bloody diarrhea, loss of appetite, and rapid dehydration. The virus attacks the cells in the intestines, preventing nutrient absorption and causing the intestines to bleed.
Parvo spreads through contaminated feces, surfaces, or even shoes. Without aggressive veterinary treatment — usually hospitalization, IV fluids, and anti-nausea medications — it can be fatal.
If your dog has bloody diarrhea and hasn’t been fully vaccinated, treat it as an emergency.
4. Intestinal Parasites
Worms such as hookworms, whipworms, or roundworms can irritate the intestinal lining and cause bloody diarrhea in dogs.
Parasites steal nutrients and damage the gut wall, leading to vomiting, bloating, and weight loss in chronic cases. Puppies and rescue dogs are especially vulnerable.
Routine deworming and regular fecal exams can prevent these parasites, but if you notice your dog passing blood or mucus with their stool, your vet will likely recommend a fecal test and targeted treatment.
5. Bacterial or Viral Infections
Infections caused by bacteria like Salmonella, Campylobacter, or Clostridium perfringens can lead to severe inflammation of the digestive tract.
These infections often result in watery or bloody diarrhea, vomiting, fever, and abdominal pain. Dogs can catch them from contaminated food, raw meat, or contact with other infected animals.
Most mild infections resolve with supportive care, but severe cases may require antibiotics and fluid therapy to prevent dehydration and secondary complications.
6. Stress Colitis
Just like people, dogs can experience digestive upset from stress. A sudden boarding stay, loud noises, or even a change in routine can trigger colitis — inflammation of the colon.
This often leads to soft stools or diarrhea with streaks of fresh blood or mucus. Though it looks dramatic, stress colitis typically resolves once the trigger is removed and your dog’s diet is stabilized.
Feeding a bland, gentle diet for a few days and providing a calm environment usually helps the intestines heal.
7. Ingesting Toxins or Foreign Objects
If your dog swallows a toxic substance, such as certain plants, medications, or chemicals, it can cause vomiting, diarrhea, and internal bleeding.
Likewise, swallowing sharp objects (like chicken bones or plastic pieces) can scrape the digestive tract and produce bloody stools or vomit.
Always treat this scenario as an emergency. Your vet may need to perform X-rays or induce vomiting (only if safe) to remove the object or toxin before it causes further damage.
Read more: Dog Pooping Blood Diarrhea and Vomiting (How serious is it?)
What to Do If Your Dog Is Sick With Diarrhea and Blood
If your dog is vomiting and passing bloody diarrhea, it’s vital to stay calm but act quickly.
First, withhold food for 12 hours to give your dog’s stomach a chance to settle — but never restrict water unless your vet advises otherwise. Dehydration can develop rapidly when a dog is both vomiting and having diarrhea.
After the short fast, reintroduce food gradually. Start with bland meals such as boiled chicken and plain white rice or prescription gastrointestinal food. Offer small, frequent portions rather than large meals.
Monitor your dog’s hydration by checking their gums and skin elasticity. If their gums are dry or sticky, or if they seem weak or lethargic, they may already be dehydrated.
Keep your dog’s environment calm and minimize stress. Avoid giving over-the-counter medications meant for humans — many can worsen the problem.
If your dog’s symptoms persist for more than 24 hours, worsen, or if there is a large amount of blood, seek veterinary help immediately.
When to Call or Visit Your Vet
Bloody diarrhea in a dog, especially when accompanied by vomiting, is never something to ignore.
Call your vet immediately if you notice:
Large amounts of bright red or dark tarry blood in the stool
Repeated vomiting or inability to keep water down
Signs of severe dehydration (sunken eyes, dry gums, weakness)
Black, coffee-ground vomit (which can indicate internal bleeding)
Pale gums or collapse
Even if your dog seems to feel better after a day, lingering blood or loss of appetite may signal an underlying condition that needs treatment. Early diagnosis makes recovery faster and safer.
Your vet may perform fecal tests, bloodwork, or imaging to determine the cause. In severe cases, hospitalization for IV fluids and supportive care may be necessary.
Read more: Dog Pooping Green Diarrhea (Common causes and what to do)
Key Takeaway
When your dog is sick with diarrhea that contains blood, it’s a clear signal that something is wrong inside their digestive system.
While mild cases may resolve with rest and a bland diet, bloody diarrhea combined with vomiting or lethargy can indicate a medical emergency.
Act quickly, keep your dog hydrated, and contact your veterinarian if symptoms persist or worsen. With prompt care, most dogs recover fully — but ignoring bloody diarrhea can lead to serious complications.
Your dog’s health can change rapidly, and trusting your instincts when something seems off is the best thing you can do as a pet parent.