Bloody Diarrhoea in Dogs: Symptoms, Causes, Treatment and Prevention

It’s scary to see blood in your dog’s stool. Whether it’s a streak, a smear or a jelly-like mess, your heart sinks and your mind races: Is this serious? Should I call the vet? What can I do right now?

You’re not alone and you’re doing the right thing by seeking answers. In this guide, we’ll walk through what bloody diarrhoea in dogs means, when to worry, what causes it and how to help your dog recover and stay healthy long term.

Let’s start with the basics.

Seeing Blood in Your Dog’s Poo – Should You Worry?

Blood in stool means there’s irritation, inflammation or bleeding somewhere in your dog’s digestive tract. It can be mild, like from eating something odd, or serious, like an infection or internal bleeding.

Any blood should be noted, but large amounts or ongoing bleeding mean it’s time to call your vet.

Why Blood Appears in Dog Stool

There are two main types of blood you might see:

• Bright red blood: This is fresh blood from the lower intestines or rectum.
• Dark, tarry stool: This is digested blood from the stomach or upper intestines.

Think of bright red blood as coming from near the exit, while black or coffee-coloured stool means bleeding higher up in the gut. Blood in stool means there’s irritation, inflammation or bleeding somewhere in your dog’s digestive tract.

When It’s Mild vs When It’s Urgent

Here’s a quick guide:

• Mild: A few streaks of blood, dog is acting normal, eating and drinking. Okay to monitor for 24–48 hours.
• Urgent: Continuous bleeding, vomiting, black stool, loss of appetite, lethargy or blood mixed throughout stool. Go to the vet immediately!

Trust your instincts. If your dog looks unwell, don’t wait. Your vet would rather see a false alarm than a late emergency.

Common Symptoms to Watch For

Bloody diarrhoea rarely comes alone. Look for these signs:

Digestive Symptoms:

• Frequent loose stools or accidents
• Mucus, jelly-like texture or foul odour
• Straining or urgency to defecate

Whole-Body Symptoms:

• Vomiting, nausea, drooling
• Lack of appetite or thirst
• Low energy or unusual sleepiness
• Abdominal pain (arched back, whining when touched)
• Dehydration signs such as dry gums, sunken eyes, tacky skin

Red Flags:

• Stool that looks like “strawberry jam”
• Weak, trembling or collapsing
• For puppies or elderly dogs, any blood = emergency

Common Causes of Bloody Diarrhoea in Dogs

Let’s break down the most common causes, from everyday mishaps to serious illnesses.

Dietary Indiscretion or Sudden Food Change 

Dogs love to sneak table scraps, garbage or new treats. Rich or spoiled food can upset their stomach and irritate the intestines.

Symptoms: Mild diarrhoea with possible streaks of blood.

Tip: Feed a bland diet and monitor, but visit a vet if it persists.

Parasites and Worms 

Hookworms, whipworms and giardia can cause bleeding and mucus. More common in puppies or dogs not regularly dewormed.

Signs: Soft stool, weight loss, dull coat, scooting.

Tip: Bring a fresh stool sample to your vet. It’s the fastest way to detect parasites!

Bacterial Infections or HGE (Hemorrhagic Gastroenteritis) 

Bacteria can trigger sudden, severe bloody diarrhoea. HGE often appears in otherwise healthy dogs.

Symptoms: “Strawberry jam” stool, lethargy, vomiting, dehydration.

Treatment: Fluids and vet care ASAP!

Viral Infections (Parvovirus) 

Parvo is a serious, contagious viral disease, most common in puppies.

Symptoms: Vomiting, loss of appetite, severe bloody diarrhoea, fever.

Always an emergency. Prevention through vaccination.

Toxins and Medication Side Effects 

Human painkillers, rat poison, cleaning chemicals and fatty scraps can cause ulcers or internal bleeding.

Tip: Never give human meds to dogs and store all toxins safely, as you would with kids!

Stress or Anxiety 

Travel, loud noises or moving homes can trigger colitis, leading to soft stool with streaks of blood. Usually mild and clears up with rest, hydration and gut support.

Food Allergies or Inflammatory Bowel Disease (IBD) 

Chronic conditions causing recurring bloody or mucousy stool, often linked to specific proteins or grains. Usually managed through hypoallergenic diets and probiotics.

Tip: Try our Probiotic for Dogs to help with inflammation!

Serious Illnesses 

Liver or kidney disease, pancreatitis, Addison’s disease or intestinal tumours can also cause bleeding. Usually come with other symptoms like weight loss, vomiting, pale gums.

What to Do If Your Dog Has Bloody Diarrhoea

Here’s a checklist for safe, immediate care:

Step 1: Stay Calm and Assess Your Dog

• Is your dog alert or weak? Eating or refusing food?
• Note the colour and consistency of stool for your vet

Step 2: Keep Them Hydrated

• Offer clean water or ice cubes frequently
• If vomiting occurs, only small sips at a time
• Any signs of dehydration = vet visit

Step 3: Feed a Bland Diet

• Boiled chicken and white rice or pumpkin and rice for fibre
• Feed small portions several times a day
• Gradually reintroduce regular food over 3–5 days

Never fast puppies or diabetic dogs! Call your vet instead.

Step 4: Do Not Give Human Medications

• Avoid human meds
• These can be toxic or mask serious illness

Step 5: Monitor and Contact Your Vet

• If no improvement after 24 hours or if symptoms worsen, see your vet
• Bring a stool sample and note what your dog ate recently

How Vets Diagnose Bloody Diarrhoea

Here’s what to expect at the clinic:

• Physical Exam: Hydration, temperature, abdominal pain
• Stool Tests: Parasites, giardia, parvo
• Blood Work: Infection, dehydration, organ function
• Imaging: X-rays or ultrasound for blockages or inflammation
• Additional Testing: Biopsies or endoscopy for chronic cases

Treatment and Recovery

Most dogs recover well with the right care, so it’s important to get them checked as soon as you’re worried or see any of the previous symptoms.

Veterinary Treatment:

• Fluids: IV or under-the-skin hydration
• Medications: Dewormers, antibiotics, gut protectants, anti-nausea drugs

At-Home Recovery:

• Continue bland diet until stool normalises
• Slowly reintroduce regular food
• Keep water available and rest time quiet
• Keep your vet up to date on their progress and any changes

Supporting the Gut During Recovery: 

Antibiotics and infections can disrupt healthy gut bacteria. Adding a dog-specific probiotic helps restore balance and prevent relapse.

A high-quality, vet-formulated probiotic like Petz Park Dog Probiotic helps restore healthy digestion and firm up stool naturally.

Supporting Overall Health: 

If your dog’s bloody diarrhoea was linked to liver stress, Liver Support for Dogs can aid recovery and detoxification. Supplements should complement, not replace, vet care.

Preventing Bloody Diarrhoea in Dogs

Here’s how to reduce the risk long term:

• Feed a consistent, balanced diet
• Avoid abrupt food changes or fatty scraps
• Maintain regular vet and deworming schedules
• Keep your dog’s environment safe
• Reduce stress with routine, exercise and enrichment toys
• Support gut health daily with dog supplements

When to See the Vet Urgently

Call your vet if you notice:

• Large or continuous blood in stool
• Black, tar-like stool
• Dog is weak, vomiting or not eating
• Puppy or elderly dog affected
• Diarrhoea lasting more than 24 hours

Final Thoughts

Bloody diarrhoea in dogs is alarming but with calm, informed action, most dogs recover quickly. Stay observant, trust your instincts and don’t hesitate to call your vet.

A happy gut means a happy dog. Supporting their digestion every day with balanced nutrition, hydration and trusted pet supplements can help prevent future tummy troubles.