Blood in Dog Stool: What It Means & When It's an Emergency
Prepared by the Waggle editorial team. This article is educational, not a diagnosis or an individual veterinary review. The original listing date is retained from legacy site metadata; the actual first-publication date was not recorded.
Photo by Tima Miroshnichenko on Pexels. Illustrative photo; not a patient or clinical diagnosis.
Seeing blood in your dog's stool is alarming. Sometimes it is a minor issue, and sometimes it is an emergency. The color and amount of blood can offer clues, but only a vet can find the cause. This guide is general information and not a diagnosis.
Two main types of blood in stool
- Bright red blood (hematochezia): fresh blood, usually from the lower digestive tract, such as the colon or rectum. It may appear as streaks or drops on the stool or as bloody diarrhea.
- Black, tarry stool (melena): digested blood from higher in the digestive tract, such as the stomach or small intestine. It can be a sign of a serious problem and needs prompt attention.
Common causes
- Colitis (inflammation of the colon), often linked to stress, diet or infection
- Dietary indiscretion, such as eating garbage or unusual food
- Intestinal parasites
- Viral infections, including parvovirus
- Bacterial infections
- Anal gland problems or small anal tears
- Hemorrhagic gastroenteritis, which causes sudden bloody diarrhea
- Foreign objects and bowel obstruction
- Toxins, including some rodent poisons that prevent blood clotting
- Ulcers, tumors and other illness
When it's an emergency
Go to an emergency clinic right away if your dog has:
- A large amount of blood, or bloody diarrhea that keeps happening
- Black, tarry stool
- Vomiting, especially with blood
- Lethargy, weakness, collapse or pale gums
- A swollen or painful belly
- Known or possible toxin exposure, including rat poison
- Blood in the stool of a puppy, especially an unvaccinated one
When it may be less urgent
A small streak of fresh blood in an otherwise healthy, bright dog that is eating and acting normally may be less urgent, but should still be checked if it lasts more than a day or happens again.
What to do now
- Take note of the color, amount and frequency
- Take a photo of the stool
- Check for anything your dog might have eaten
- Keep water available
- Call a vet, and do not give human medications
What a vet may do
A vet may perform an exam, test the stool for parasites and infections, order bloodwork or X-rays and treat the cause. Treatment may include fluids, medication and diet changes.
You can chat with a licensed vet on Waggle Vet to help decide how urgent it is. If your dog is showing emergency signs, go straight to an emergency vet near me.
FAQs
Is blood in dog stool always serious?
Not always, but it should never be ignored.
Can stress cause bloody stool in dogs?
Yes, stress can trigger colitis, but a vet should rule out other causes.
What if my dog's stool is black?
Treat it as urgent and contact a vet right away.
Check current Waggle Vet access and eligibility terms. Talk to a vet now.
Related reading
- Why Is My Cat Throwing Up? 8 Common Causes & When to See a Vet
- Dog Grooming Tips: A Vet's Guide to At-Home Care
- Dog Ear Mites: How to Identify and Treat Them Fast
- Flea Treatment for Dogs: What Actually Works in 2026
Waggle resources
Find nearby veterinary clinics; call to confirm availability
Still have questions?
For non-emergency questions, explore Waggle Vet. Trouble breathing, collapse, suspected poisoning or other severe signs need immediate in-person emergency care—do not wait for an online chat.
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