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Urgent care is for pets who are unwell, in discomfort, are in urgent situation or are not acting like themselves and should be assessed within 24 hours.
Wellness, routine, or general care is for pets needing vaccines, preventive care, or ongoing monitoring who can safely wait at least 24 hours.
This page focuses on urgent assessment. Routine wellness exams, preventive care, and monitoring of stable conditions are provided through scheduled general wellness appointments.
Blood in Stool in Dogs or Cats (Bloody Diarrhea)
Bloody diarrhea or blood in stool in dogs and cats can range from mild intestinal irritation to life-threatening internal disease, depending on the source of bleeding, volume of blood, speed of onset, and whether dehydration or shock is developing.
Common search terms include blood in dog poop, bloody diarrhea, black tarry stool, hematochezia, and melena in pets.
Definition
Bloody diarrhea or blood in stool is a clinical sign, not a diagnosis. It refers to visible red blood, dark tar-colored stool, or blood-tinged diarrhea passed from the gastrointestinal tract.
Bright red blood usually suggests lower intestinal or colonic irritation, while black or tarry stool often reflects digested blood from the stomach or upper intestines.
Because bleeding can be mild, intermittent, or internally progressive, the appearance of stool alone cannot determine severity.
Locally and globally, blood in stool is a high-risk gastrointestinal sign that often warrants urgent veterinary assessment to determine cause and stability.
Who This Page Is For
Dogs or cats with visible blood in stool or diarrhea
Pets with dark, black, or tar-like stools
Pets with bloody stool plus vomiting, lethargy, or weakness
Puppies or kittens with any amount of bloody diarrhea
Senior or medically fragile pets with new GI bleeding
Who This Page Is Not For
Pets with one isolated, tiny blood streak associated with firm stool that immediately resolves
If you are unsure whether this is significant, that uncertainty itself warrants veterinary assessment.
Related Urgent Symptoms
Dog Diarrhea
Vomiting And Diarrhea
Dog Vomiting Blood (Hematemesis)
Cat Vomiting Blood (Hematemesis)
Dog Lethargic and Weak
Cat Lethargic and Weak
Pale Gums (Emergency)
Dehydration
What This Can Look Like at Home
Bloody stool may appear as bright red streaks, clots, jelly-like mucus mixed with blood, or watery diarrhea with red discoloration.
Some pets pass very dark, sticky, tar-like stool that smells unusually strong.
Bleeding may be intermittent, making it easy to underestimate severity.
Why This Can Be Hard to Judge
Some pets may not show overt signs of illness, even while losing fluid or blood internally.
Small amounts of blood can look dramatic but be mild, while serious bleeding may initially appear subtle.
Blood loss, dehydration, and electrolyte imbalance can develop before outward weakness is obvious.
The source of bleeding cannot be determined reliably without diagnostic testing.
The Improvement Trap
Temporary improvement does not equal resolution.
Bleeding may stop briefly, then recur as inflammation, ulceration, infection, or obstruction progresses.
This pattern is common with intestinal parasites, foreign material, ulcer disease, or hemorrhagic syndromes.
What Is Easy to Miss at Home
Ongoing internal blood loss without visible stool changes
Rapid dehydration from fluid loss
Pale gums indicating anemia or shock
Subtle weakness or reduced interaction
Electrolyte imbalances affecting heart and muscle function
These hidden changes often determine how urgent the situation truly is.
When This Can Be an Emergency
Bloody diarrhea or blood in stool requires urgent care assessment when any of the following are present:
Large volumes of blood or continuous bleeding
Black or tarry stool
Vomiting, especially with blood
Marked lethargy, weakness, or collapse
Pale gums or rapid breathing
Puppies or kittens with bloody stool
Known or suspected toxin exposure
Abdominal pain or bloating
How Veterinarians Assess This
Clinical signs alone cannot reliably determine severity.
Symptoms can appear similar while representing very different internal disease processes. Diagnostic testing is how veterinarians determine whether a condition is mild and self-limiting or serious and potentially life-threatening, and how they guide appropriate care.
Diagnostic testing may include:
Bloodwork (CBC and chemistry) to assess anemia, inflammation, dehydration, and organ function
Fecal testing to evaluate parasites and infectious causes
Abdominal imaging to assess intestinal structure, masses, or obstruction
Coagulation testing when bleeding disorders or toxins are suspected
Urinalysis to assess hydration and systemic disease
Additional disease-specific testing (such as infectious disease screening, endocrine testing, advanced imaging, or gastrointestinal endoscopy) may be considered based on the overall clinical picture.
Diagnostic testing is what determines severity and guides appropriate care.
Veterinary Differentials - Serious / Must-Rule-Out First
Acute hemorrhagic diarrhea syndrome (AHDS), causing sudden intestinal bleeding and rapid dehydration.Tests may include bloodwork, packed cell volume, total solids, fecal testing, and abdominal imaging.
Gastrointestinal ulceration or bleeding, where stomach or intestinal lining erosion causes blood loss.Tests may include bloodwork, abdominal imaging, coagulation testing, and endoscopic evaluation.
Parvovirus infection, especially in puppies with severe bloody diarrhea.Tests may include fecal antigen testing, bloodwork, electrolyte analysis, and infectious disease testing.
Rodenticide or toxin exposure, interfering with normal clotting.Tests may include coagulation testing, bloodwork, and toxin screening.
Intestinal obstruction or foreign body, causing tissue damage and bleeding.Tests may include abdominal radiographs, abdominal ultrasound, and bloodwork.
Veterinary Differentials - Common / More Typical
Colitis, where lower intestinal inflammation leads to bright red blood.Tests may include fecal testing, bloodwork, and abdominal imaging.
Intestinal parasites, disrupting intestinal lining integrity.Tests may include fecal flotation, fecal antigen testing, and parasite screening.
Dietary indiscretion, irritating the gastrointestinal tract.Tests may include fecal testing, bloodwork, and abdominal imaging.
Bacterial or protozoal infection, causing mucosal inflammation.Tests may include fecal PCR testing, fecal antigen testing, and bloodwork.
Stress-related gastrointestinal inflammation, especially in dogs.Tests may include fecal testing, bloodwork, and imaging.
Safety, Psychology, & Peace of Mind
Blood in stool is alarming because it signals internal injury or inflammation.
Waiting can be risky when bleeding, dehydration, or anemia is developing silently.
Veterinary assessment replaces fear and guessing with clarity by identifying the bleeding source and stability.
Early evaluation often prevents progression to shock or hospitalization.
Frequently Asked Questions
Is bloody diarrhea or blood in stool in dogs and cats an emergency?
Bloody diarrhea or blood in stool in dogs and cats can range from mild to serious, depending on the underlying cause. Because outward appearance does not reliably indicate internal risk, this sign is treated as urgent. Same-day urgent care is recommended, especially if bleeding is persistent, worsening, or accompanied by lethargy, vomiting, or weakness.
My pet seems normal now — can bloody stool still be serious?
Yes. Pets often hide illness, and blood in stool may temporarily improve even while the underlying problem persists. Apparent normal behavior does not reliably reflect internal stability, which is why veterinary assessment is appropriate even when bleeding appears mild or intermittent.
What if the blood only happened once or seems mild?
Even a single episode of blood in stool can be clinically meaningful. Temporary improvement does not equal resolution, and waiting to see if it happens again can delay identification of more serious disease. Early assessment helps determine whether the issue is self-limiting or progressing.
Why are tests needed if we can already see blood in the stool?
Clinical signs alone cannot determine severity or cause. Diagnostic testing is how veterinarians identify the source of bleeding, assess internal impact such as anemia or dehydration, and distinguish minor irritation from potentially serious disease. Testing replaces guesswork with clarity and guides appropriate care.
What should I do right now if my pet has blood in the stool?
Do not rely on watchful waiting. Bloody diarrhea or blood in stool warrants veterinary assessment, particularly if it is persistent, recurring, or associated with lethargy, weakness, vomiting, pale gums, or behavioral changes. Same-day urgent care helps reduce risk and determine next steps.